Isolator vs. Solenoid vs. Combiner
Chris Wolf
I'm confused!
After running down the starter battery in my camper van a few times with my
television and lights, I've decided to add a deep-cycle battery to my
electrical system so I can still start the engine in the morning. I
understand that it's important to keep the two batteries separated, so the
starter battery can start the engine, and the deep-cycle battery can run
everything else. But I'm getting a real difference of opinion on the best
way to do it.
The battery isolator people say an isolator is the way to go. No moving
parts, and no maintenance. But the solenoid people say the isolator can
prevent your batteries from fully recharging (voltage drop across the
diodes), and can shorten their lives of the batteries.
The solenoid people say a continuous-duty solenoid is the way to go. No
voltage drop; no recharge problems. But doesn't the solenoid permit the
two batteries to zap each other when they're finally reconnected? It's my
understanding that if I run down the deep-cycle battery, and then turn the
key to start the engine the next morning, that the solenoid will reconnect
the two batteries. Then the starter battery will try to recharge the
deep-cycle battery, and drain the starter battery. I've heard that this
current surge is very hard on batteries and wiring.
I've also heard that a battery combiner is the best way to go. If I
understand it correctly, the combiner keeps the deep-cycle battery out of
the circuit until the engine is running, and the alternator is charging the
starter battery. Then the combiner switches in the deep-cycle battery, and
everybody lives happily ever after.
I'm kinda new to this, and don't know who to believe. Can someone please
set me straight? Thanks!
Chris Wolf
cwo...@attbi.com
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Will Sill
> . . . doesn't the solenoid [isolator] permit the
>two batteries to zap each other when they're finally reconnected? It's my
>understanding that if I run down the deep-cycle battery, and then turn the
>key to start the engine the next morning, that the solenoid will reconnect
>the two batteries. Then the starter battery will try to recharge the
>deep-cycle battery, and drain the starter battery. I've heard that this
>current surge is very hard on batteries and wiring.
Chris, I've had trouble with diode-based isolators in the past, but
never had a minute's trouble with the relay deal. They are cheap,
simple and dependable. The bozos telling you all the stories about
them are trying to sell you expensive alternatives to a simple
problem.
"Most people are about as happy as they make up their
minds to be." [A. Lincoln]
Will KD3XR
GBinNC
wrote:
>I'm confused!
Hey, Chris --
So am I, sometimes. But not on this topic. <g>
For about $18 you can buy (from WWGrainger, part #6C017) a
continuous-duty solenoid -- or relay, if you want to call it that --
that when correctly installed (easy) will automatically connect the
two batteries *only* when the ignition is on (or in "accessories"
position), which means that the engine alternator will charge the
house battery along with the engine battery.
This is the way my Class B came from the factory. I replaced the relay
once when it started acting up, and the Grainger one (actually made by
White-Rodgers) was an exact replacement of the original.
HTH.
GB in NC
Hughbd1
Yabut, nobody seems to be addressing Chris's question. He is more
concerned about depleting his deep cycle battery, then turning on his
ignition and having his starting battery try to recharge the deep cycle
battery. Seems like it may be a valid concern. I don't worry 'cause I
tow a trailer. If we are dry camping, I leave the trailer plug unhooked
until the truck starts and then plug in the trailer.
If the deep cycle battery was heavily discharged, couldn't it really hog
the starting battery down rather fast?
Hugh
Chris Wolf
>>On Wed, 08 May 2002 21:23:05 -0700, Chris Wolf <cwo...@attbi.com>
>>wrote:
>>
>>I'm confused!
>Hey, Chris --
>
>So am I, sometimes. But not on this topic. <g>
>
>For about $18 you can buy (from WWGrainger, part #6C017) a
>continuous-duty solenoid -- or relay, if you want to call it that --
>that when correctly installed (easy) will automatically connect the
>two batteries *only* when the ignition is on (or in "accessories"
>position), which means that the engine alternator will charge the
>house battery along with the engine battery.
That seems like a cheap, simple solution. And good solenoids are very
reliable. And I like the idea of no voltage drop problems, which seem to
be a problem with the battery isolators.
But I don't understand how the solenoid solution prevents the starter
battery from trying to recharge the house battery when the ignition is
turned on. Let's say I stop for the night and turn off the ignition. The
solenoid de-energizes and disconnects the two batteries. Now I can run my
house battery all night without fear of draining my starter battery. But
in the morning, when I turn on the ignition to start the engine, the
solenoid reconnects the two batteries. Instantly the fully-charged starter
battery will try to recharge the depleted house battery. I understand this
is very hard on the batteries and the wiring, at least until the engine
gets running and the alternator starts charging both batteries. Or at
least this is how it's been described to me. Am I overlooking something
here?
I've heard that a battery combiner avoids the problem by waiting until the
engine is running, and the alternator is charging the starter battery,
before switching the house battery back into the circuit. Supposedly this
avoids the problem of the starter battery zapping the depleted house
battery before the alternator gets going.
I know battery combiners are expensive, and I sure like the idea of the
solenoid solution, but I'm worried about the battery zap problem. Am I
worrying unnecessary?
Chris Wolf
>Yabut, nobody seems to be addressing Chris's question. He is more
>concerned about depleting his deep cycle battery, then turning on his
>ignition and having his starting battery try to recharge the deep cycle
>battery. Seems like it may be a valid concern.
Actually it's just the other way around. I'm not worried about depleting
my deep cycle battery. If I manage to run it down, I'll just turn off the
lights and TV and watch my battery-powered DVD player. I just want to make
sure that when I try to start the engine in the morning, the starter
battery hasn't been run down along with the deep cycle battery. So I
understand the importance of disconnecting the two batteries from each
other before settling down for the night.
But in the morning, I'm concerned about reconnecting the two batteries
before the alternator gets running, and having the starter battery trying
to recharge the depleted deep cycle battery (at least until the alternator
gets running, and starts charging both batteries).
>I don't worry 'cause I
>tow a trailer. If we are dry camping, I leave the trailer plug unhooked
>until the truck starts and then plug in the trailer.
Good solution.
>If the deep cycle battery was heavily discharged, couldn't it really hog
>the starting battery down rather fast?
That's my understanding. Now the starter battery has been depleted, trying
to recharge the deep cycle battery, and if you don't go for a long drive to
get the starter battery recharged, isn't it possible that you might have
insufficient power to start the engine the next time?
I guess my question is whether or not reconnecting the two batteries, via
the solenoid, when the starter battery is charged, and the deep cycle
battery is depleted, causes damage to the batteries as they try to recharge
each other.
George E. Cawthon
No, unless the electric system is wired really screwy. If
you have a Ford pickup with a towing package, you get a
relay to charge the trailer battery as part of that
package. The trailer battery only connects into the system
after the engine is started and the alternator is pumping
electrons. There is no way the trailer battery, discharged
or not, will have any effect on the charge of the starter
battery. In a regular tow vehicle there is no connection to
the trailer battery when the key is in the accessory
position. Don't know about Class B's, but I can't imagine
why they would wire the house battery that way either.
BTW, what is a combiner? another name for an isolator
(diode)?
That same system is likely to be rather universal.
bill horne
Yes. All you have to do is find the correct source to power the
solenoid. Have you noticed that when the ignition switch is in the ON
position that the heater fan and radio (and various other accessories)
work? But that when you go to the START position, the radio and the fan
stop?
--
bill
Theory don't mean squat if it don't work.
Tom J
"Chris Wolf" <cwo...@attbi.com> wrote in message
news:p6hldusoc3ih44gmk...@4ax.com...
>
> But I don't understand how the solenoid solution prevents the starter
> battery from trying to recharge the house battery when the ignition is
> turned on. Let's say I stop for the night and turn off the ignition.
The
> solenoid de-energizes and disconnects the two batteries. Now I can run
my
> house battery all night without fear of draining my starter battery.
But
> in the morning, when I turn on the ignition to start the engine, the
> solenoid reconnects the two batteries.
Chris, it's very simple. No matter which of the three methods you
mentioned that you are considering, they ALL connect the two batteries
together when you crank the engine. That 2 or 3 second delay of the
combiner doesn't amount to squat, and is a huge waste of money, that could
better be spent on refreshments.
Tom J
Tom J
"George E. Cawthon" <George...@worldnet.att.net> wrote in message
news:3C3CA777...@worldnet.att.net...
>
> BTW, what is a combiner? another name for an isolator
> (diode)?
That, or a solenoid in a fancy box. ;-)
Tom J
Will Sill
type of isolator:
>If the deep cycle battery was heavily discharged, couldn't it really hog
>the starting battery down rather fast?
Even in theory is it so unlikely as to be more rare than gas pumps
exploding. The wire carrying juice between the two batteries limits
the current draw, and if yer starting battery is so weak it won't
crank with an extra small load you are in deep doodoo already.
For anyone seriously nervous about such a remote possibility, put in a
switch to disable the relay until you are started up and running.
That way you can forget it is off and be back where you started.
Will KD3XR
Will Sill
without thinking (sumthin' new, eh?):
Sorry I was not thinking - and I see where Bill Horne was. I guess he
doesn't have much to do but think and kill fire ants!
He's right, of course - wire the dang relay to the accessory terminal
and the whole question is moot.
Society is always taken by surprise at any new
example of common sense. [R W Emerson]
Will KD3XR
John A. Mooney
ignition switch 'on' for long periods of time. It goes through the 'on'
position for a few milliseconds before going to the 'start' position. The
solenoid is a tried-and-true setup, as well as being inexpensive. Hook the
little wire to an electrical source that is controlled by the ignition
switch.
Chris Wolf <cwo...@attbi.com> wrote in article
<p6hldusoc3ih44gmk...@4ax.com>...
dave martin
> concerned about depleting his deep cycle battery, then turning on his
> ignition and having his starting battery try to recharge the deep cycle
> battery. Seems like it may be a valid concern. I don't worry 'cause I
> tow a trailer.
Two relays in series are sufficient.
One relay is activated by the chassis battery in series with the
ignition key.
The second relay is activated by the coach battery.
In this setup the chassis battery is hooked to the coach battery only
when the ignition is on and the chassis battery is charged and the
coach battery is charged.
Therefore if the coach batteries are so low they can't energize their
own relay they are disconnected from the chassis battery however once
this situation happens the alternator can't charge the coach
batteries.
My setup is slightly different; the second relay mentioned above is
activated by the chassis battery through a switch. (The problem here
is I've got to know when the coach batteries are dead to tell me to
throw the switch.)
It seems to me that the best wiring of the relays would be a
combination of the above where the coach batteries are activated only
when the switch (normally off) is thrown OR when the the coach battery
has enough charge to throw its own relay.
The first setup I described with strategically placed manual switches
would allow one to manually connect the coach batteries to the chassis
power system in the event that the chassis battery dies.
David Osborn
>> Yabut, nobody seems to be addressing Chris's question. He is more
>> concerned about depleting his deep cycle battery, then turning on his
>> ignition and having his starting battery try to recharge the deep cycle
>> battery. Seems like it may be a valid concern. I don't worry 'cause I
>> tow a trailer.
>
>Two relays in series are sufficient.
*One* relay is sufficient. Anything more needlessly complicates the setup.
--
David, N8DO; FMCA 147762
djosborn at aol dot com
jhn...@hal-pc.org
In the real world:
Using a solenoid to disconnect the engine from the MH batteries, the
controling voltage is obtained from the accessory bus. What this does
is shut off the solenoid when the key is off and you will not deplete
the engine battery while camped.
When you go to start and turn the key through run (monentaraily) to
the start position, the solenoid cycles on for a second and then goes
off when you get to the start position. This lets the engine battery
use its full capability to run the starter and crank the engiie. With
a poor battery or in cold weather you may need all the energy in the
battery to crank.
As soon as the engine starts, you release the key and it returns to
the run position and the accessory bus is connected to the
alternator/engine battery bus. This turns on the relay and connects
the MH battery to the alternator/engine battery bus and charges the MH
battery (along with the engine battery).
Unless you turn the key to run position and leave, with out the
engine running, the engine battery will not charge the MH battery. Why
you would turn the key to the run position and let set with engine off
I don't know????
Bottom line. Diode isolation will work and relay cut off will work.
The one you understand and think is best for you, then you should go
that way.
And may you'all have happy motoring and easy starting in the mornings.
Big John - KR5K
Robert Vette
Chris said;
I guess my question is whether or not reconnecting the two batteries,
via the solenoid, when the starter battery is charged, and the deep
cycle battery is depleted, causes damage to the batteries as they try to
recharge each other.
Chris Wolf
*****************************************
Chris, on our motor home the relay is powered from a separate output of
the alternator that has no connection to the battery. Only has power
when the alternator is turning fast enough to put out 12 volts. Before
the days of EFI this separate output was used to power electric choke
heaters. Possibly the same thing could be accomplished using the oil
pressure switch. But I wouldn't worry about it anyway. Use the
accessory output from the ignition switch. Worst you could do is end up
with two batteries each half charged and that will start an engine just
fine.
Bob
Tom J
"Robert Vette" <hrv...@webtv.net> wrote in message
news:13722-3CD...@storefull-2336.public.lawson.webtv.net...
>
> Chris said;
>
> I guess my question is whether or not reconnecting the two batteries,
> via the solenoid, when the starter battery is charged, and the deep
> cycle battery is depleted, causes damage to the batteries as they try to
> recharge each other.
> Chris Wolf
If you are still worried about that, get the diode isolator. The flow
there is only from the alternator to the batteries. That's what I've been
using for the last 20+ years, after I ran all my batteries down in the
worst place it could possibly happen in the area.
Tom J
OOPS - just told why I say "if you don't have something to isolate the
batteries, one of the days you'll have dead batteries in the worst
possible place!!"
Chris Wolf
>>"Robert Vette" <hrv...@webtv.net> wrote in message
>>news:13722-3CD...@storefull-2336.public.lawson.webtv.net...
>>
>> Chris said;
>>
>> I guess my question is whether or not reconnecting the two batteries,
>> via the solenoid, when the starter battery is charged, and the deep
>> cycle battery is depleted, causes damage to the batteries as they try to
>> recharge each other.
>> Chris Wolf
>If you are still worried about that, get the diode isolator.
That's just the point. I don't know whether to be worried about it, or
not. Nobody seems to have a definitive answer. Maybe there isn't one.
I would have thought that some smart electrical engineer would have written
up a detailed analysis of the various ways to handle the battery separation
question, with a listing of the pros and cons for both methods, but I sure
haven't been able to find one so far.
b b
djos...@aol.commnet.net says...
batteries. I have never had one bit of problem with that arrangement,
and it is simple to understand too. In addition, if the starting battery
is low, I will activate the Start Boost switch (that closes the relay
shorting the two batteries together) so the starting battery can charge
from the generator via the converter that charges the house batteries.
I am not at all concerned that discharged house batteries could deplete
the starting batteries before the vehicle starts. The voltage in the
house batteries would very quickly reach 12 volts and stop drawing much
current. It takes over 13 volts to continue to charge the house
batteries, and that will not be there until the engine is running.
My vote would be one relay shorting the two batteries together when the
engine is running, and a push button switch on the panel that activates
the same relay to start when the starting battery is depleted, as GB
recommended. This system works very well, is inexpensive, and reliable.
Regards,
Barrie B.
bill horne
>
> Tom J writes:
>
> >>"Robert Vette" <hrv...@webtv.net> wrote in message
> >>news:13722-3CD...@storefull-2336.public.lawson.webtv.net...
> >>
> >> Chris said;
> >>
> >> I guess my question is whether or not reconnecting the two batteries,
> >> via the solenoid, when the starter battery is charged, and the deep
> >> cycle battery is depleted, causes damage to the batteries as they try to
> >> recharge each other.
> >> Chris Wolf
>
> >If you are still worried about that, get the diode isolator.
>
> That's just the point. I don't know whether to be worried about it, or
> not. Nobody seems to have a definitive answer. Maybe there isn't one.
>
> I would have thought that some smart electrical engineer would have written
> up a detailed analysis of the various ways to handle the battery separation
> question, with a listing of the pros and cons for both methods, but I sure
> haven't been able to find one so far.
>
> Chris Wolf
What is it you don't understand that requires an electrical engineer?
For years, I used a plain ole starter solenoid from the auto parts
store, and wired it so that it was engaged ONLY when the ignition switch
was in the ON position. I never had a problem.
I might also add that the Nervous Nellie Electrical Engineer position
that the starter solenoid is not designed for continuous operation,
never resulted in any problems, either.
Vince Wirth
<bnbUNDER...@a1above.net.USE_forUNDERSCORE> wrote:
Barrie writes;
>My vote would be one relay shorting the two batteries together when the
>engine is running, and a push button switch on the panel that activates
>the same relay to start when the starting battery is depleted, as GB
>recommended. This system works very well, is inexpensive, and reliable.
I'm with that 100%. Nobody mentioned during this thread, the current
drawn by the starter which is over 150 Amps on a normal vehicle.
Now, if you look at the potential difference between the vehicle battery
and the house battery plus the resistance path, I suspect that the
current draw from the chassis battery is about 1/3 that of the starter.
So. the few milliseconds that the key takes going from off to start. The
House battery will draw less that a Amp hour from the chassis battery.
In other words --- NO Problem.
Vince
dave martin
> dma...@newarts.com writes (in part):
>
> >> Yabut, nobody seems to be addressing Chris's question. He is more
> >> concerned about depleting his deep cycle battery, then turning on his
> >> ignition and having his starting battery try to recharge the deep cycle
> >> battery. Seems like it may be a valid concern. I don't worry 'cause I
> >> tow a trailer.
> >
> >Two relays in series are sufficient.
>
> *One* relay is sufficient. Anything more needlessly complicates the setup.
You are wrong if the relay is energized by the chassis battery thru
the ignition switch as there is no automatic way to prevent dead or
shorted coach batteries from being put in parallel with the chassis
system.
You are right if the relay is powered by the coach batteries (not the
ignition switch); this is sufficient to insure that only charged coach
batteries are in parallel with the chassis battery.
But this arrangement has serious practical problems:
First, when the ignition is off and the coach batteries are being used
both battery systems will discharge until the coach relay drops out;
at this point the chassis battery is essentially discharged.
Second, connecting the coach batteries directly to the coach relay
will put a constant load on the coach batteries so the first problem
is sure to arise.
Clearly at least a manual switch to disconnect the coach batteries
from the relay is required for storage conditions.
Third, if the coach batteries are too low to activate the relay that
connects them to the chassis system they won't get charged by the
alternator system.
Therefore some way to force discharged coach batteries in parallel
with the chassis system is desireable.
There is simply no way to automatically accomplish what the original
poster's request implies with one relay.
If you have a concrete solution please share it with us.
John S
cwo...@attbi.com says...
>
> I'm confused!
<snip>
> But doesn't the solenoid permit the
> two batteries to zap each other when they're finally reconnected? It's my
> understanding that if I run down the deep-cycle battery, and then turn the
> key to start the engine the next morning, that the solenoid will reconnect
> the two batteries. Then the starter battery will try to recharge the
> deep-cycle battery, and drain the starter battery. I've heard that this
> current surge is very hard on batteries and wiring.
also. I have measured this surge current with a peak reading,
maxhold clamp on DC ammeter and was initially amazed at how small the
current surge was, even with a pair of 8Ds for each battery bank.
Then, it dawns on you. You are charging a dead battery with a
battery that puts out a voltage of at most 12.8VDC. And, 12.8VDC
driving the internal resistance of both batteries does not produce
much current flow!
Note: The solenoid wiring was very low resistance 00 battery cable so
that the diesel pusher house batteries could be also be used to boost
start the engine if the engine starting batteries had somehow been
discharged.
Consider the case of delaying the solenoid closure until the engine is
revved up and the alternator is outputting the normal 14 to 14.4 VDC.
Then, the solenoid contacts would have to handle a huge surge current
into the dead battery and I would expect arcing and *maybe* reduced
solenoid life.
And, as many others on this thread have stated, the simple solenoid
approach is by far the most common setup and has served RVers well for
many years without any significant problems.
John
George E. Cawthon
and also sell diodes. End of story.
IF YOU CAN'T SWIM DON'T JUMP IN
how about combining the 2 batteries!
its just that word SHORT that brings the smell of burnt plastic to the
nose!
kc
Bob Crockett
comments are my best knowledge from years of electrical/electronic
technician-level work, not engineering. Second, I could be wrong.
Having said _that_: with a solid state isolator, there will be a small
voltage drop between the input from the alternator and the output to the
batteries, maybe 2/10ths of a volt. With a relay (or solenoid)
separator, there is normally no voltage drop. Switching of the power to
the relay from either the alternator's output or the oil pressure switch
will not allow the batteries to try to equalize their voltage for even
the short time that powering the relay from the accessory rail will.
So, I suppose the relay powered from the alternator or oil pressure
switch would be the theoretical "best" approach.
I changed the old relay system on my '73 Dodge motorhome to an isolator
system to eliminate the possibility of the relay sticking. The 1973
model relay was stuck, and I sucked the house battery too low to crank
the engine. A new relay "shouldn't" stick. A solid state isolator
_cannot_ stick, as there are no moving parts to stick. Getting or
giving a jump start from either of your batteries and momentarily
connecting the jumper cables will probably short out the isolator and
you'll need to change your underwear. But you'll be a lot more careful
after _that_ experience!
Bottom line: Take your choice (flip a coin!), as both methods have many
diehard supporters and satisfied users.
It ain't worth worrying about!
Bob
Bob Crockett
I said: I sucked the house battery too low to crank the engine.
When I obviously meant "sucked the _chassis_ battery...."
Although actually they were both discharged to uselessness and I had to
swallow my pride and ask for help.
(Damn, I just _HATE_ that!)
Glenn
We dry camp 40 weekends each year. We can go all weekend using lights,
microwave, tv, toaster oven, furnace ect on battery power. Our setup
uses 3 battery banks , one large battery for engine start, a pair of 90
amp hour sealed lead acid batteries for 12 volt lighting & power, a pair
of 235 amp hour 6 volt golf cart batteries in series for the 110 volt
inverter. We use 4 gauge wire between the 2 solenoids and I am sure
there is lots of power flowing back & forth when i turn the key. This
system has been working fine for me for 160,000 miles over 5 years. I
have replaced both solenoids once but the batteries have served well. (
my 120 amp alternator gets replaced about every 13 months But it works
hard)
Like buckets of water, if a full battery fills an empty battery the
"Juice" is not lost it is just equalized.
Ps, The sine wave inverter does use 25% less power when running motors,
microwave or anything with a power transformer
Good luck
Glenn
kward
another for the house battery.
KLW
"John S" <camper1...@yahoo.com> wrote in message
news:MPG.1744ed5d9...@news-01.easynews.com...
Will Sill
>Two relays in series are sufficient.
>
>One relay is activated by the chassis battery in series with the
>ignition key.
>
>The second relay is activated by the coach battery.
Dave, I have never seen such a setup and marvel at the (apparently)
unnecessary complexity. I continue to believe that a single
continuous-duty "solenoid" relay actuated by the accessory source is
fully adequate. Certainly a relay can fail, but few things made by
man are totally reliable.
Will Sill
>I would have thought that some smart electrical engineer would have written
>up a detailed analysis of the various ways to handle the battery separation
>question, with a listing of the pros and cons for both methods, but I sure
>haven't been able to find one so far.
You don't get it. You got EXCELLENT advice based on long experience.
It is not all 100% in agreement, so you may be compelled to use your
own brain - if any!
Will Sill KD3XR
Some bright fellow once remarked:"I get tired of explaining
the obvious to the oblivious" and I wanted to use it but
I am too cheap to pay royalties so I won't.
Will Sill
>What is it you don't understand that requires an electrical engineer?
He doesn't understand good advice when he sees it.
>For years, I used a plain ole starter solenoid from the auto parts
>store, and wired it so that it was engaged ONLY when the ignition switch
>was in the ON position. I never had a problem.
>
>I might also add that the Nervous Nellie Electrical Engineer position
>that the starter solenoid is not designed for continuous operation,
>never resulted in any problems, either.
I don't doubt for a second that you have been lucky not to fry the
starter solenoid. But despite the similar appearance and function,
the two are different. The one designed for starting use has a
relatively high-current relay coil intended to assure a very solid
connection, and a heavy return spring to assure a clean beak. The
coil draws more juice and heats the whole relay a lot when
continuously actuated. Normally they will fail early when used that
way.
By contrast the continous-duty style is designed for far less current
draw, and has a high-impedance coil and a light return spring - which
no doubt accounts for the occasional report of one hanging up. Still,
they don't overheat in use,
Sorry, but despite Bill's good luck I hafta recommend the
continuous-duty type.
b b
hrv...@webtv.net says...
> Worst you could do is end up
> with two batteries each half charged and that will start an engine just
> fine.
>
>
with only 12 volts on them. They require over 13 volts to accept much
charge. The "problem" of a well charged battery charging a discharged
battery in a short time is just... non-existant. Not a thing to worry
about.
The thing to worry about is having two charged batteries that are hooked
in parallel without any isolator discharging each other over long term
due to slightly different voltages on each battery. The key word here is
LONG TERM....weeks.
A single relay that is activated to connect the two batteries to charge
them from one alternator output works fine.
Regards,
Barrie B
b b
cwo...@attbi.com says...
> That's just the point. I don't know whether to be worried about it, or
> not. Nobody seems to have a definitive answer. Maybe there isn't one.
>
> I would have thought that some smart electrical engineer would have written
> up a detailed analysis of the various ways to handle the battery separation
> question, with a listing of the pros and cons for both methods, but I sure
> haven't been able to find one so far.
>
>
>
try to summarize.
Relay to connect the two batteries, activated from ignition switch:
PRO:
1. Simple
2. Inexpensive
3. Easy to understand
4. Reliable
5. Connects the batteries without a voltage drop so they charge properly
with the factory setting of the vehicle's voltage regulator
6. Easy to add a switch to activate the relay to jump the two batteries
to act as "Jumper Cables" for starting in emergency.
CON:
None I can think of unless you believe mechanical contacts are
unreliable; Then you need to worry about your whole starting system too,
which is mechanical contact based.
Diode Isolators
PRO:
1. No moving contacts
CON:
1. Voltage drop of the diodes requires compensating voltage increase in
the voltage requlator; This is sometimes not possible with stock voltage
regulators. If the voltage regulator does NOT get compensated, the diode
isolators will NOT fully charge the battery in any reasonable time. You
will always be running with an undercharged battery, inviting sulfation.
2. Adding a switch to "Jump" the batteries together for emergency
starting requires a relay just like used for the "charge them together"
relay above. (Note that this relay will STILL connect the batteries
together)
3. Usually more expensive
The rest of the schemes are complicated based on unreasonable fears. I
cannot find ANY reasonable PROs for them.....the CONS are added
complexity, cost, difficulty of understanding, reliability, and
debugging.
In closing, for years we have not hesitated to use jumper cables to start
vehicles with dead batteries. In many such connections of a dead battery
and a fully charged battery, I have experienced NO damage to either
battery due to this connection. This connection typically lasts much
longer than it takes to start the engine. The worry about connecting
dead to fully charged batteries is a groundless fear. (I am curious
about where you picked up this concern?)
I hope this helps,
Barrie B
Chris Wolf
>>Chris said;
>>
>>I guess my question is whether or not reconnecting the two batteries,
>>via the solenoid, when the starter battery is charged, and the deep
>>cycle battery is depleted, causes damage to the batteries as they try to
>>recharge each other.
>Chris, on our motor home the relay is powered from a separate output of
>the alternator that has no connection to the battery. Only has power
>when the alternator is turning fast enough to put out 12 volts. Before
>the days of EFI this separate output was used to power electric choke
>heaters. Possibly the same thing could be accomplished using the oil
>pressure switch.
I think those are excellent ideas, Robert. Instead of connecting the two
batteries, via solenoid, the moment the ignition switch is turned, the
depleted house battery is not switched back into the charging circuit until
the starter battery has started the engine, and the alternator is pumping
out the juice. In that way, both batteries are kept totally isolated until
the engine is running, and charging current is available. And whatever
problems (if any) that exist when a depleted house battery is connected to
a charged starter battery, become moot.
I've heard that there are "smart solenoids" being manufactured that do not
activate until the current exceeds 13 volts (i.e. the engine is running).
Then the solenoid switches on, and the house battery is switched into the
charging circuit. This strikes me as the very best solution of all. I
will see what I can find.
Has anyone else heard of those "smart solenoids"?
Thanks for the excellent advice, Robert!
Chris Wolf
>>Chris Wolf wrote:
>>
>> I would have thought that some smart electrical engineer would have written
>> up a detailed analysis of the various ways to handle the battery separation
>> question, with a listing of the pros and cons for both methods, but I sure
>> haven't been able to find one so far.
>What is it you don't understand that requires an electrical engineer?
The same question I have asked repeatedly. When connecting a depleted
house battery to a fully charged starting battery, via a solenoid, does the
sudden rush of current and voltage from the starter battery, into the house
battery, threaten to damage the batteries or the wiring?
That was the specific question I asked, and no one seemed to know the
answer. I figured it would take an electrical engineer to answer such a
question.
>For years, I used a plain ole starter solenoid from the auto parts
>store, and wired it so that it was engaged ONLY when the ignition switch
>was in the ON position. I never had a problem.
You were lucky. You were using a part in a situation it was never designed
for. It's like using a 10 amp fuse in a 20 amp circuit, and just hoping
that it never blows.
>I might also add that the Nervous Nellie Electrical Engineer position
>that the starter solenoid is not designed for continuous operation,
>never resulted in any problems, either.
There are very good reasons why you don't use a momentary contact solenoid
in an application that requires a continuous-duty solenoid. Why on earth
would you want to take the risk of burning up the solenoid?
That's a pretty dumb thing to do.
Chris Wolf
>>bill horne <red...@rye.net> recently wrote these words:
>>
>>What is it you don't understand that requires an electrical engineer?
>He doesn't understand good advice when he sees it.
Oh I understand good advice just fine. I also know that you haven't given
me any, so far. The fact that you, personally, have had no problems with a
solenoid system, proves nothing.
I asked a specific question about combining batteries via a solenoid, and
instead of answering it, you simply assured me that the solenoid system
would work fine. I'm afraid I need something a little more substantial
than that.
Fortunately there do seem to be other people, on this list, who do
understand how to answer a question.
Chris Bryant
>I've heard that there are "smart solenoids" being manufactured that do not
>activate until the current exceeds 13 volts (i.e. the engine is running).
>Then the solenoid switches on, and the house battery is switched into the
>charging circuit. This strikes me as the very best solution of all. I
>will see what I can find.
>
>Has anyone else heard of those "smart solenoids"?
>
>Thanks for the excellent advice, Robert!
>
>Chris Wolf
>cwo...@attbi.com
>
There are at least a couple that I know of- one by Sure Power:
http://www.surepower.com/separator.html
The others by Intellitec:
http://www.intellitecsve.com/battery.htm scroll down to Isolator relay
delay- Battery isolator control, and Bi Directional Isolator relay
delay.
They both offer both standard and bi-directional (which would
keep the coach battery charged when hooked to shore power- they sense
when either battery is being charged).
I don't know about the Sure Power, but the Intellitec has a
couple of nice features- the cheaper models can be added to any
existing relay (saving money if you already have a relay)- and the
Diesel model uses a diesel starting (400-600 amp) solenoid, but cuts
the coil voltage down after engaging- so you can use an intermittent
rated solenoid for continuous duty.
--
Chris Bryant
Bryant RV Services- http://www.bryantrv.com
Chris Wolf
>OK, Chris, I'll take a swat at it. First, I need to say that these
>comments are my best knowledge from years of electrical/electronic
>technician-level work, not engineering.
No problem. For theory, I go to the engineers. For practical, hands-on
experience, I'll take a technician any day. They know what's practical,
and what isn't. Something can work great in the lab, but be utterly crummy
out in the field.
>Second, I could be wrong.
>Having said _that_: with a solid state isolator, there will be a small
>voltage drop between the input from the alternator and the output to the
>batteries, maybe 2/10ths of a volt.
I've heard that it can be as high as 7/10ths of a volt. Either way, it can
result in your batteries not getting fully recharged, and failing
prematurely. Apparently there are ways to correct this voltage drop
problem, but the solenoid looks like a simpler solution to me.
>With a relay (or solenoid)
>separator, there is normally no voltage drop. Switching of the power to
>the relay from either the alternator's output or the oil pressure switch
>will not allow the batteries to try to equalize their voltage for even
>the short time that powering the relay from the accessory rail will.
>So, I suppose the relay powered from the alternator or oil pressure
>switch would be the theoretical "best" approach.
That was also Robert Vette's suggestion, and I agree with both of you.
However I think there's an even better solution, called the "Smart
Solenoid." It monitors the voltage in the system, and doesn't energize the
relay until the voltage rises above 13 volts (when the engine is running).
This means the house battery is not switched into the charging system, with
the starter battery, until the engine is started and the alternator is
putting out the juice. I've just found such a solenoid from Sure Power.
It's called a "battery separator," model #1314, for about $70. Since it
monitors the voltage, you don't even have to hook it up to the alternator
or oil pressure switch; just connect it between the batteries.
I don't know that using an ordinary relay to connect the batteries would
cause any damage to the batteries or wiring, but the Smart Solenoid would
seem to make the concern moot. I think I'll give it a try.
>I changed the old relay system on my '73 Dodge motorhome to an isolator
>system to eliminate the possibility of the relay sticking. The 1973
>model relay was stuck, and I sucked the house battery too low to crank
>the engine.
I'm sure you meant to write "starter battery." So you ended up with two
dead batteries. Bummer!
Obviously one of the drawbacks of the relay is that can stick shut, and end
up draining both batteries. Maybe I'll attach one of those little voltage
shutoff boxes to the starter battery. It disconnects the battery if the
voltage threatens to fall so low that the battery can no longer start the
engine. I have one on my jeep, and it seems to work pretty well. One
night I left the dome light on overnight. The next morning the light was
out, but the battery still had enough power to start the engine.
>A new relay "shouldn't" stick. A solid state isolator
>_cannot_ stick, as there are no moving parts to stick. Getting or
>giving a jump start from either of your batteries and momentarily
>connecting the jumper cables will probably short out the isolator and
>you'll need to change your underwear. But you'll be a lot more careful
>after _that_ experience!
Yeah, that's the main reason I elected to go with a solenoid, rather than a
solid-state isolator. The isolator has no moving parts to fail, but it
seems like there are a number of other ways to screw it up. I'm sure I'd
find one!
Thanks for the info, Bob! It's exactly what I was looking for.
David Osborn
>djos...@aol.commnet.net (David Osborn) wrote in message
>news:<20020509181856...@mb-fs.aol.com>...
>> dma...@newarts.com writes (in part):
>>
>> >> Yabut, nobody seems to be addressing Chris's question. He is more
>> >> concerned about depleting his deep cycle battery, then turning on his
>> >> ignition and having his starting battery try to recharge the deep cycle
>> >> battery. Seems like it may be a valid concern. I don't worry 'cause I
>> >> tow a trailer.
>> >
>> >Two relays in series are sufficient.
>>
>> *One* relay is sufficient. Anything more needlessly complicates the setup.
>
>You are wrong if the relay is energized by the chassis battery thru
>the ignition switch as there is no automatic way to prevent dead or
>shorted coach batteries from being put in parallel with the chassis
>system.
Numerous years of experience -- by others as well as by me -- clearly indicate
that a single-relay system works quite well, and that there is no problem when
a discharged coach battery is connected to the chassis battery (when the
ignition switch is moved to the "on" position after starting the engine) by
that relay.
>You are right if the relay is powered by the coach batteries (not the
>ignition switch); this is sufficient to insure that only charged coach
>batteries are in parallel with the chassis battery.
If the coach batteries were already charged, then they wouldn't need to be
connected to the chassis battery, now would they?
>But this arrangement has serious practical problems:
>
>First, when the ignition is off and the coach batteries are being used
>both battery systems will discharge until the coach relay drops out;
>at this point the chassis battery is essentially discharged.
This is one of the very good reasons why the relay is there to keep them
separated when the engine isn't running.
>Second, connecting the coach batteries directly to the coach relay
>will put a constant load on the coach batteries so the first problem
>is sure to arise.
We don't want that, now do we?
>Clearly at least a manual switch to disconnect the coach batteries
>from the relay is required for storage conditions.
Manual switches have a strange tendency to become forgotton switches.
>Third, if the coach batteries are too low to activate the relay that
>connects them to the chassis system they won't get charged by the
>alternator system.
That's right.
>Therefore some way to force discharged coach batteries in parallel
>with the chassis system is desireable.
That's what the single relay, which is energized when the ignition switch is in
the "Acc" or "On" position, is used.
>There is simply no way to automatically accomplish what the original
>poster's request implies with one relay.
Yes, there is -- and it's been used for many years.
>If you have a concrete solution please share it with us.
I already have.
Chris Wolf
A truly EXCELLENT summation, Mr. B. Thanks a million! That is exactly the
sort of information I was looking for. It gives a clear summation of the
pros and cons for each method.
Your point about using jumper cables to connect a dead battery with a fully
charged battery is a good one. However I wonder if we might not be
comparing apples and oranges. A jump start is something we only do once in
a great while, whereas connecting two different battery systems in an RV is
something done on a daily basis. It is possible that using an ordinary
solenoid to connect the two batteries is like getting a jump start on a
daily basis? In other words, what is okay to do once in a great while,
with no appreciable damage, may be a very different concern when done on a
daily basis. Perhaps every time the solenoid reconnects a depleted house
battery to a charged starter battery, a small amount of damage is done, and
this can build up over the months, causing premature battery failure?
I became concerned about using an ordinary solenoid to connect the two
batteries, precisely because it looks exactly like a jump start, and I was
always taught to do jump starts only when absolutely necessary, because it
was hard on the batteries. I'd be delighted to find out that I was wrong.
Thanks again!
Chris Wolf
>>Chris Wolf wrote:
>>
>>I've heard that there are "smart solenoids" being manufactured that do not
>>activate until the current exceeds 13 volts (i.e. the engine is running).
>>Then the solenoid switches on, and the house battery is switched into the
>>charging circuit. This strikes me as the very best solution of all. I
>>will see what I can find.
>>
>>Has anyone else heard of those "smart solenoids"?
>There are at least a couple that I know of- one by Sure Power:
>http://www.surepower.com/separator.html
>The others by Intellitec:
>http://www.intellitecsve.com/battery.htm scroll down to Isolator relay
>delay- Battery isolator control, and Bi Directional Isolator relay
>delay.
Thanks for the info, Mr. Bryant. Much appreciated!
Will Sill
>The same question I have asked repeatedly. When connecting a depleted
>house battery to a fully charged starting battery, via a solenoid, does the
>sudden rush of current and voltage from the starter battery, into the house
>battery, threaten to damage the batteries or the wiring?
What part of "no" don't you understand?
<remainder of rant snipped>
In view of your apparent obsession on this topic, I suggest you avoid
any contact with low-voltage DC systems. You've had an estimated
dozen people with hands-on experience answer your question - not to
mention several with obviously extensive knowledge of the theory.
But you keep harping as though you are spoiling for a fight. Were
you rejected as a candidate for a Judge Judy show?
DISCLAIMER:
My advice is useless. I have no university degrees and have never
towed a 34' TT with an Intrepid. Though I have done some
near-Darwin-award dumb things in the past, and often still make
errors, I currently own NO Banks headers, fuel magnets, deer whistles
or louvered tailgates. I've never deliberately allowed a holding tank
to freeze solid, and have no financial interest in whether you join
RVCG, wear clothes, overinflate your tires or hate Firestone. I do
however hold an Advanced Class Amateur Radio license and have worked
extensively as a volunteer electrician. Still, if you take my advice,
I guarantee absolutely NOTHING. Got that?
Will Sill KD3XR
Chris Wolf
>>Chris Wolf <cwo...@attbi.com> recently wrote these words:
>>
>>I would have thought that some smart electrical engineer would have written
>>up a detailed analysis of the various ways to handle the battery separation
>>question, with a listing of the pros and cons for both methods, but I sure
>>haven't been able to find one so far.
>You don't get it. You got EXCELLENT advice based on long experience.
>It is not all 100% in agreement, so you may be compelled to use your
>own brain - if any!
Get lost, creep. You've been 100% worthless.
What a stupid jackass!
Chris Wolf
>Chris Wolf <cwo...@attbi.com> recently wrote these words:
>
>>The same question I have asked repeatedly. When connecting a depleted
>>house battery to a fully charged starting battery, via a solenoid, does the
>>sudden rush of current and voltage from the starter battery, into the house
>>battery, threaten to damage the batteries or the wiring?
>What part of "no" don't you understand?
What part of the word "proof" or "evidence" are you unfamiliar with?
You can't just say "no," and expect me to take it on faith. You must
explain WHY there is no threat of damage. Other people on this list have
done just that, and so their advice has been useful to me. You have not
bothered to do so, and so your advice is worthless to me.
> <remainder of rant snipped>
>
>In view of your apparent obsession on this topic, I suggest you avoid
>any contact with low-voltage DC systems. You've had an estimated
>dozen people with hands-on experience answer your question - not to
>mention several with obviously extensive knowledge of the theory.
And those who took the trouble to support their claims, with arguments or
data, have been most useful to me, and I thank them for taking the time to
give me a detailed answer.
You, on the other hand, have given me nothing but an unsupported claim, and
then criticized me for asking for detailed proof. So get lost, Crackpot.
>But you keep harping as though you are spoiling for a fight. Were
>you rejected as a candidate for a Judge Judy show?
Son, you're the one who accused me, repeatedly, of not knowing good advice
when I see it. You're the one who seems to be spoiling for a fight. So go
fuck yourself, Moron. I don't need to listen to the braying of mindless
jackasses like you, who become petulant when asked to provide proof of
their claims
b b
cwo...@attbi.com says...
> I became concerned about using an ordinary solenoid to connect the two
> batteries, precisely because it looks exactly like a jump start, and I was
> always taught to do jump starts only when absolutely necessary, because it
> was hard on the batteries. I'd be delighted to find out that I was wrong.
>
>
>
because it is a pain to do it unnessesarily and you always have the risk
(however low)of the spark that flashes when connecting the jumper clips
igniting hydrogen gas given off by the battery, or accidently shorting
the clips making a REAL surge. I cannot possibly believe the current
surge from the charged battery to the more discharged battery would
exceed the 300 or 400 amps drawn by the starter, which does not damage
the battery. Notice I said MORE DISCHARGED battery; if you repeatedly
totally discharge the battery (even though it is a "deep discharge"
battery) it will be much more surely destroyed than by the surge created
by hooking the batteries together. The deep discharge batteries should
best not be regularly discharged below 50% charge before recharging.
THIS is the problem you should spend time and money avoiding to preserve
battery life, not the "connection surge".
You asked my opinion; it is "Use the single relay to charge both your
batteries". I cannot say more than that; it's your time and money, so
the final DECISION is yours... :-)
Good luck deciding what is best for you....
Barrie B
Chris Wolf
>In article <ap9odu46q8qhk6p8r...@4ax.com>,
>cwo...@attbi.com says...
>> I became concerned about using an ordinary solenoid to connect the two
>> batteries, precisely because it looks exactly like a jump start, and I was
>> always taught to do jump starts only when absolutely necessary, because it
>> was hard on the batteries. I'd be delighted to find out that I was wrong.
>I think I would do jump starts only when necessary myself, but more
>because it is a pain to do it unnessesarily and you always have the risk
>(however low)of the spark that flashes when connecting the jumper clips
>igniting hydrogen gas given off by the battery, or accidently shorting
>the clips making a REAL surge.
Very true.
>I cannot possibly believe the current
>surge from the charged battery to the more discharged battery would
>exceed the 300 or 400 amps drawn by the starter, which does not damage
>the battery.
Seems like a reasonable assumption. But does the fact that it's less
drain, guarantee that there is no battery damage done when the two
batteries are tied together when in very different states of discharge?
Are the two situations equal in every way? I don't know. I'm not a
battery engineer. But over the years, I've heard it said that one should
not permit a fully charged battery to drain into a charged battery, even
for sort periods of time.
Maybe this is one of those things that most of the time you can get away
with, but not always. I dunno.
>Notice I said MORE DISCHARGED battery; if you repeatedly
>totally discharge the battery (even though it is a "deep discharge"
>battery) it will be much more surely destroyed than by the surge created
>by hooking the batteries together. The deep discharge batteries should
>best not be regularly discharged below 50% charge before recharging.
>THIS is the problem you should spend time and money avoiding to preserve
>battery life, not the "connection surge".
Good point, but I figure the purpose of the deep discharge battery is to
serve my needs during the night. If that means drawing it down, and
replacing it more often, so be it.
It would be nice if I could add another deep discharge battery, and
increase capacity, but I just don't have any more room in my little Ford
Econoline van.
>You asked my opinion; it is "Use the single relay to charge both your
>batteries". I cannot say more than that; it's your time and money, so
>the final DECISION is yours... :-)
And that is what I ended up doing. Using a single relay to charge both
batteries. However I decided to spend a little more money on the relay,
and get one of the "Smart Solenoids" from Sure Power. It has a computer
chip to monitor the voltage of the system, and it only connects the house
battery, via the solenoid, when the system voltage rises above 13 volts
(when the engine and alternator is running). This gives me the simplicity
and reliability of a solenoid, but guarantees that the two batteries are
never tied together, except when charging. So I will never have to worry
about damaging the batteries by connecting them before the alternator
starts to charge them.
Best of all worlds! ;-)
Thanks again for your good advice.
GBinNC
<George...@worldnet.att.net> wrote:
>In a regular tow vehicle there is no connection to
>the trailer battery when the key is in the accessory
>position. Don't know about Class B's, but I can't imagine
>why they would wire the house battery that way either.
My Class B is wired that way. The relay/solenoid that connects the
chassis and house batteries activates when the key is in either "on"
or "accessories."
I like it what way, because any time it's plugged in to shore power I
can leave the key on "accessories" and automatically charge the
chassis battery from the converter -- and also use the radio, dome
lights, etc. without running down the chassis battery.
GB in NC
GBinNC
wrote:
>But I don't understand how the solenoid solution prevents the starter
>battery from trying to recharge the house battery when the ignition is
>turned on. Let's say I stop for the night and turn off the ignition. The
>solenoid de-energizes and disconnects the two batteries. Now I can run my
>house battery all night without fear of draining my starter battery. But
>in the morning, when I turn on the ignition to start the engine, the
>solenoid reconnects the two batteries. Instantly the fully-charged starter
>battery will try to recharge the depleted house battery. I understand this
>is very hard on the batteries and the wiring, at least until the engine
>gets running and the alternator starts charging both batteries. Or at
>least this is how it's been described to me. Am I overlooking something
>here?
Chris, all I know is that I haven't had even a hint of a problem with
my system -- even once when I mistakenly depleted the house battery
almost completely. I simply turned the key and started the engine. I
didn't notice any difference whatsoever.
The reason I know the Grainger part number is that Chris Bryant was
good enough to look it up for me last year when the original relay on
my van began working erratically (causing the house battery not to be
recharged while driving).
I had been quoted $70 from an RV dealer for a generic replacement
relay. The $18 one from Grainger was a perfect match -- actually an
improvement, in that it had an added external ground terminal rather
than being grounded through the base. The ground connection on the
original had corroded, which was part of its problem.
GB in NC
Chris Wolf
>On Thu, 09 May 2002 12:01:37 -0700, Chris Wolf <cwo...@attbi.com>
>wrote:
>
>>But I don't understand how the solenoid solution prevents the starter
>>battery from trying to recharge the house battery when the ignition is
>>turned on. Let's say I stop for the night and turn off the ignition. The
>>solenoid de-energizes and disconnects the two batteries. Now I can run my
>>house battery all night without fear of draining my starter battery. But
>>in the morning, when I turn on the ignition to start the engine, the
>>solenoid reconnects the two batteries. Instantly the fully-charged starter
>>battery will try to recharge the depleted house battery. I understand this
>>is very hard on the batteries and the wiring, at least until the engine
>>gets running and the alternator starts charging both batteries. Or at
>>least this is how it's been described to me. Am I overlooking something
>>here?
>Chris, all I know is that I haven't had even a hint of a problem with
>my system -- even once when I mistakenly depleted the house battery
>almost completely. I simply turned the key and started the engine. I
>didn't notice any difference whatsoever.
I wouldn't expect you to notice any difference. At least not right away.
If there is any damage done by connecting a depleted battery to a charged
battery, using an ordinary solenoid, it must be minor damage, or else
people would be reporting damaged batteries all the time.
But my concern is with possible long-term damage to the batteries. If
every time the solenoid closes, the batteries are damaged slightly, and if
the damage is cumulative, then I would expect the batteries to wear out
prematurely. This is something that might not be readily noticed right
away; sort of like the long-term damage from smoking.
Certainly there are some people in the business who claim that the standard
solenoid arrangement definitely causes damage to the batteries. Here's a
quote from the web page of the Sure Power Corporation. They've been
building battery isolators for thirty years, and they claim to be the
original inventors of the battery isolator.
BEGIN QUOTE:
"One of the "so-called" solutions for multi-battery drain is nothing more
than a solenoid, a switch that disconnects batteries one from another.
With a solenoid, there's no multi-battery drain while the batteries are
disconnected. But the second the solenoid reconnects the batteries, the
drained battery robs power from the starting battery. That isn't all that
happens. This sudden violent transfer of energy from one battery to
another has been known to damage batteries or shorten their life, and
overheat wires and connections. And worst of all, cause fires. The
solenoid is no solution for muti-battery drain!"
END QUOTE
Now of course the Sure Power people might not be telling the truth. Or
perhaps they are simply wildly exaggerating. After all, they sell
solid-state battery isolators, so perhaps we should not be surprised when
they attack the solenoid solution. But does this mean there isn't a word
of truth in the Sure Power claims? I don't know. I'm not a battery
engineer. But it certainly makes me wonder. Which is why I asked the
question, here on the list, if using a regular solenoid can cause damage to
the batteries.
Some people have stated that they have used the solenoid solution for many
years, with no problems. I wish that were enough to convince me, but it's
not. Some people smoke without getting lung cancer, but that doesn't mean
cigarettes are safe. It's obvious that the solenoid vs. isolator debate
has been going on for a long time, with neither side able to definitively
prove its claims.
So I have decided to adopt a conservative solution, and use a Smart
Solenoid that only joins the two batteries together when the engine and
alternator are actually running. Then I don't have to worry about any
possible damage to the batteries, with one battery trying to charge the
other whenever the ignition key is turned on.
Interestingly enough, the Smart Solenoid is made by the Sure Power company!
Apparently they don't object to the solenoid solution as long as the two
batteries aren't connected when the engine isn't running.
Or at least as long as you buy their $100 solenoid. ;-)
I don't much care to pay $100 for a lousy solenoid, but until I see
definitive proof that an ordinary solenoid causes no damage to the
batteries, I consider it to be cheap insurance.
And that definitive proof will have to be more than a blind assurance from
Will Sill. ;-)
dave martin
> that a single-relay system works quite well
I don't disagree. One works quite well for me, but does not satisfy
the original poster's requirement than low coach batteries not be
placed in parallel with the chassis system.
More that one relay is required for that condition to be met
automatically.
Whether it makes much difference in the practical world is a different
matter.
GBinNC
wrote:
>So I have decided to adopt a conservative solution, and use a Smart
>Solenoid that only joins the two batteries together when the engine and
>alternator are actually running. Then I don't have to worry about any
>possible damage to the batteries, with one battery trying to charge the
>other whenever the ignition key is turned on.
>
>I don't much care to pay $100 for a lousy solenoid, but until I see
>definitive proof that an ordinary solenoid causes no damage to the
>batteries, I consider it to be cheap insurance.
To be honest, I had never even considered the damage you described. I
agree that what you say makes sense, although my limited experience
doesn't seem to support it.
I've had an AGM house battery for a couple of years. It's connected to
the chassis battery via solenoid, and I've never given a second
thought to the possibility that it is being damaged because of it.
I'll let you know how long it lasts...
GB in NC
John S
cwo...@attbi.com says...
> I think those are excellent ideas, Robert. Instead of connecting the two
> batteries, via solenoid, the moment the ignition switch is turned, the
> depleted house battery is not switched back into the charging circuit until
> the starter battery has started the engine, and the alternator is pumping
> out the juice. In that way, both batteries are kept totally isolated until
> the engine is running, and charging current is available. And whatever
> problems (if any) that exist when a depleted house battery is connected to
> a charged starter battery, become moot.
>
> I've heard that there are "smart solenoids" being manufactured that do not
> activate until the current exceeds 13 volts (i.e. the engine is running).
> Then the solenoid switches on, and the house battery is switched into the
> charging circuit. This strikes me as the very best solution of all. I
> will see what I can find.
>
> Has anyone else heard of those "smart solenoids"?
>
> Thanks for the excellent advice, Robert!
>
> Chris Wolf
entirely unneeded for any simple dual battery setup. Just more stuff
to break!
In fact, as I stated in my other post, it may do more harm than good
because of the high solenoid switching current when energized after
the engine is revved up. The maximum alternator output current of
today's big alternators is typically well over 100 amps!
With the simple solution, the good battery does NOT significantly
charge the dead battery so there is no problem! This is
easily verified by measurements as well as theory and I have done
it both ways.
If it ain't broke, don't fix it.
And, if you expect:
> I would have thought that some smart electrical engineer would have written
> up a detailed analysis of the various ways to handle the battery separation
> question, with a listing of the pros and cons for both methods, but I sure
> haven't been able to find one so far.
We EEs do not work for free - Do you?
Or, are you just trolling?
John
Jon Porter
"Chris Wolf" <cwo...@attbi.com> wrote in message
news:hkvodussalb6oj099...@4ax.com...
> BEGIN QUOTE:
>
> "One of the "so-called" solutions for multi-battery drain is nothing more
> than a solenoid, a switch that disconnects batteries one from another.
> With a solenoid, there's no multi-battery drain while the batteries are
> disconnected. But the second the solenoid reconnects the batteries, the
> drained battery robs power from the starting battery. That isn't all that
> happens. This sudden violent transfer of energy from one battery to
> another has been known to damage batteries or shorten their life, and
> overheat wires and connections. And worst of all, cause fires. The
> solenoid is no solution for muti-battery drain!"
>
> END QUOTE
>
It's a non-problem. The solenoid closes when the ignition is switched on and
the alternator is running. The alternator provides more than enough juice to
power the vehicle and charge both batteries. The cranking battery doesn't
get drained at all in this case, so there's no extra damage. Note that the
cranking battery gets drained every time you turn over the engine, and thus
requires recharging.
If you wan't assurance that your charging system isn't draining one battery
to feed another, then go with a diode isolator, which is specifically
designed to prevent that. I've been using Isolators for years with no
battery destruction problems. People have been doing likewise with
soleniods, which are pretty much isolators with moving parts.
bill horne
>
> bill horne writes:
>
> >>Chris Wolf wrote:
> >>
> >> I would have thought that some smart electrical engineer would have written
> >> up a detailed analysis of the various ways to handle the battery separation
> >> question, with a listing of the pros and cons for both methods, but I sure
> >> haven't been able to find one so far.
>
> >What is it you don't understand that requires an electrical engineer?
>
> The same question I have asked repeatedly. When connecting a depleted
> house battery to a fully charged starting battery, via a solenoid, does the
> sudden rush of current and voltage from the starter battery, into the house
> battery, threaten to damage the batteries or the wiring?
It never damaged mine. Is there a sudden rush with the alternator
running?
> That was the specific question I asked, and no one seemed to know the
> answer. I figured it would take an electrical engineer to answer such a
> question.
>
> >For years, I used a plain ole starter solenoid from the auto parts
> >store, and wired it so that it was engaged ONLY when the ignition switch
> >was in the ON position. I never had a problem.
>
> You were lucky. You were using a part in a situation it was never designed
> for. It's like using a 10 amp fuse in a 20 amp circuit, and just hoping
> that it never blows.
I'm lucky a lot, I guess. But if I hadn't been, I'd just bought another
one. They're cheap - or they were.
> >I might also add that the Nervous Nellie Electrical Engineer position
> >that the starter solenoid is not designed for continuous operation,
> >never resulted in any problems, either.
>
> There are very good reasons why you don't use a momentary contact solenoid
> in an application that requires a continuous-duty solenoid. Why on earth
> would you want to take the risk of burning up the solenoid?
Everything I do is a risk. In this case, I decided to try to try a cheap
starter solenoid (since I don't hold to the theory that you get what you
pay for), and it never blew. I've still got it, but I don't use it
anymore. Let me shock you further: When I got my 96 trucklet, I decided
to not mess with solenoids, diodes, or switches. I just hooked my TT 12
volt line to an Aux terminal under the hood. That terminal is hot with
the ignition switch off. Although I ran the TT battery down a few times,
I never had a problem starting after I hooked up. Nor did I let the
smoke out of anything.
So what we have here is over a decade on a starter solenoid, and about 5
years on nothing at all, I've had no problems with a vampire battery
sucking all the juice out of my truck battery, or smoking anything. In
between, I tried a 50 amp diode from Radio Shack. Regardless of the much
hyped voltage drop, I had no problem with that, either.
> That's a pretty dumb thing to do.
I'm just lucky, I guess - like the bumblebee. Maybe God loves a Dog
drinker.
So do what you want, buddy. It ain't my money, and I rarely spend more
money than I have to on the basis of some theory.
> Chris Wolf
As a matter of interest, how many have had direct personal experience
with a starter solenoid in this application? Did it fail? How long did
it last before it failed?
I'll start. I have direct personal experience. It never failed. It
lasted for well over 25,000 miles of ON time, and had not failed when I
retired it.
--
bill
Theory don't mean squat if it don't work.
bill horne
> Your point about using jumper cables to connect a dead battery with a fully
> charged battery is a good one. However I wonder if we might not be
> comparing apples and oranges. A jump start is something we only do once in
> a great while, whereas connecting two different battery systems in an RV is
> something done on a daily basis. It is possible that using an ordinary
> solenoid to connect the two batteries is like getting a jump start on a
> daily basis? In other words, what is okay to do once in a great while,
> with no appreciable damage, may be a very different concern when done on a
> daily basis. Perhaps every time the solenoid reconnects a depleted house
> battery to a charged starter battery, a small amount of damage is done, and
> this can build up over the months, causing premature battery failure?
Or perhaps there isn't. I never had a problem - that I know of. Perhaps
my battery would have lasted 6 years, instead of 5, if I hadn't hooked
them together with a cheap starter solenoid every time I started up.
Perhaps I should give a damn, but I don't. 5 years on is fine with me.
> Chris Wolf
bill horne
Then you, like me, are just lucky you haven't blown up any batteries. I
guess that shoots a hole in my "God loves a Dog drinker" (Gasp!) theory.
bill horne
My TT batteries usually last about 5 years. My vehicle batteries usually
last about 6 years. And that's also true on my vehicles that don't tow
anything, and have only one battery to worry about. I can draw a
tentative conclusion from that. This is beginning to resemble the
White/Black Pyramid discussions.
jhn...@hal-pc.org
The answer to your question is no. Ok?
Big John - KR5K
On Fri, 10 May 2002 12:14:30 -0700, Chris Wolf <cwo...@attbi.com>
wrote:
>bill horne writes:
jhn...@hal-pc.org
wrote:
----clip----
>
>I've heard that it can be as high as 7/10ths of a volt. Either way, it can
>result in your batteries not getting fully recharged, and failing
>prematurely.
Wrong
Apparently there are ways to correct this voltage drop
>problem, but the solenoid looks like a simpler solution to me.
Wrong
I'm assuming from your prior postings you just want the answer(s) and
not the reason why?
----clip----
Big John - KR5K
jhn...@hal-pc.org
wrote:
----clip----
. I'd be delighted to find out that I was wrong.
----dlip----
Your wrong.
Big John - KR5K
jhn...@hal-pc.org
I don't think you can win with Chris? You give him excellent advice in
a clear concise manner and he says he is not an engineer and then
wants to argue with you????
I for one, would like to thank you for trying to help a poor lost
soul.
Big John KR5K
On Fri, 10 May 2002 13:08:34 -0400, b b
<bnbUNDER...@a1above.net.USE_forUNDERSCORE> wrote:
>In article <13722-3CD...@storefull-2336.public.lawson.webtv.net>,
>hrv...@webtv.net says...
>> Worst you could do is end up
>> with two batteries each half charged and that will start an engine just
>> fine.
>>
>>
>This is FAR worse than could ever happen; batteries do not charge much
>with only 12 volts on them. They require over 13 volts to accept much
>charge. The "problem" of a well charged battery charging a discharged
>battery in a short time is just... non-existant. Not a thing to worry
>about.
>
>The thing to worry about is having two charged batteries that are hooked
>in parallel without any isolator discharging each other over long term
>due to slightly different voltages on each battery. The key word here is
>LONG TERM....weeks.
>
>A single relay that is activated to connect the two batteries to charge
>them from one alternator output works fine.
>
>Regards,
>Barrie B
jhn...@hal-pc.org
Good real world advice.
Big John KR5K
On Sat, 11 May 2002 03:59:52 GMT, John S <camper1...@yahoo.com>
wrote:
Chris Wolf
>Chris
>
>The answer to your question is no. Ok?
>
>Big John - KR5K
No, it's not okay. If you make a claim, you must support it with some
evidence. Or at least a logical argument.
A claim without evidence or argument is worthless. It's as though nothing
has been said at all. You might as well claim you have a gold mine in your
back yard. Without evidence, the claim is worthless.
Chris Wolf
>Wrong
>Wrong
In your case, I don't think I want either one. You sound as Silly as
Willy.
Chris Wolf
Chris Wolf
>Barrie
>
>I don't think you can win with Chris? You give him excellent advice in
>a clear concise manner and he says he is not an engineer and then
>wants to argue with you????
Actually I thanked Barrie for his good advice. Learn to read, Moron.
b b
cwo...@attbi.com says...
> And that is what I ended up doing. Using a single relay to charge both
> batteries. However I decided to spend a little more money on the relay,
> and get one of the "Smart Solenoids" from Sure Power. It has a computer
> chip to monitor the voltage of the system, and it only connects the house
> battery, via the solenoid, when the system voltage rises above 13 volts
> (when the engine and alternator is running). This gives me the simplicity
> and reliability of a solenoid, but guarantees that the two batteries are
> never tied together, except when charging. So I will never have to worry
> about damaging the batteries by connecting them before the alternator
> starts to charge them.
>
>
Does the "Smart Solenoid" have a way to connect a switch so you can force
the solenoid to close if the starting battery needs a boost from the
house battery to start the engine? This is a really nice feature that I
do occasionally use.
Happy Camping,
Barrie B
Will Sill
>As a matter of interest, how many have had direct personal experience
>with a starter solenoid in this application? Did it fail? How long did
>it last before it failed?
>
>I'll start. I have direct personal experience. It never failed. It
>lasted for well over 25,000 miles of ON time, and had not failed when I
>retired it.
My turn. Sent a guy to the NAPA store to ask for the continuous duty
variety when we were building an ambulance. The clerk sold him the
wrong one because neither of them knew any better and my helper
installed the thing. It smoked inside a day. Though I don't
remember what brand it was I am pretty sure it was not made in China.
Will KD3XR
David Osborn
>So I have decided to adopt a conservative solution, and use a Smart
>Solenoid that only joins the two batteries together when the engine and
>alternator are actually running. Then I don't have to worry about any
>possible damage to the batteries, with one battery trying to charge the
>other whenever the ignition key is turned on.
That's an elegant -- and expensive -- solution to a simple problem. The
starting battery is *designed* to deliver large current flows for a few
seconds. After all, when the engine is started the battery delivers a few
hundred Amperes to the starter. Therefore, we know that it won't be damaged by
whatever current it supplies to a discharged battery. Furthermore, the Smart
Solemoid does *nothing* to prevent a large current flow to the discharged coach
battery -- it simply delays the start of the flow by a few seconds. Therefore,
we know that it can't prevent any damage that might occur to the coach battery.
>Interestingly enough, the Smart Solenoid is made by the Sure Power company!
>Apparently they don't object to the solenoid solution as long as the two
>batteries aren't connected when the engine isn't running.
That's correct.
>Or at least as long as you buy their $100 solenoid. ;-)
You're getting the picture.
>I don't much care to pay $100 for a lousy solenoid, but until I see
>definitive proof that an ordinary solenoid causes no damage to the
>batteries, I consider it to be cheap insurance.
If years and years of experience by thousands and thousands of people isn't
enough "definite proof" for you, then go ahead and purchase your expensive
"insurance" against a non-problem!
--
David, N8DO; FMCA 147762
djosborn at aol dot com
David Osborn
>djos...@aol.commnet.net (David Osborn) wrote in message
>news:<20020510161112...@mb-mc.aol.com>...
>> dma...@newarts.com writes:
>>
>> >djos...@aol.commnet.net (David Osborn) wrote in message
>> Numerous years of experience -- by others as well as by me -- clearly
>indicate
>> that a single-relay system works quite well
>
>I don't disagree. One works quite well for me, but does not satisfy
>the original poster's requirement than low coach batteries not be
>placed in parallel with the chassis system.
The coach batteries *must* be placed in parallel with the chassis system at
some point in order to receive a charge -- unless one wants to go to a
completely separate alternator charging system for the coach batteries.
>More that one relay is required for that condition to be met
>automatically.
Nope. Even if *five* relays are used in series, then there will still
*eventually* be a connection between the two battery systems.
>Whether it makes much difference in the practical world is a different
>matter.
Whether or not "it makes much difference in the practical world" is the *heart*
of this issue.
b b
GBi...@yahoooo.com says...
> >But I don't understand how the solenoid solution prevents the starter
> >battery from trying to recharge the house battery when the ignition is
> >turned on. Let's say I stop for the night and turn off the ignition. The
> >solenoid de-energizes and disconnects the two batteries. Now I can run my
> >house battery all night without fear of draining my starter battery. But
> >in the morning, when I turn on the ignition to start the engine, the
> >solenoid reconnects the two batteries. Instantly the fully-charged starter
> >battery will try to recharge the depleted house battery. I understand this
> >is very hard on the batteries and the wiring, at least until the engine
> >gets running and the alternator starts charging both batteries. Or at
> >least this is how it's been described to me. Am I overlooking something
> >here?
>
> Chris, all I know is that I haven't had even a hint of a problem with
> my system -- even once when I mistakenly depleted the house battery
> almost completely. I simply turned the key and started the engine. I
> didn't notice any difference whatsoever.
>
>
"big surge" that is feared just DOES NOT HAPPEN. The spark you get when
you jump a dead battery is a teeny one (but large enough to ignite
hydrogen gas), not the big fat one you would get if you would jump right
to a starter motor......and that big starting surge happens every time
you start. It does not damage your battery either....the battery is
designed for that surge.
I am still looking for the source of the "damaging surge" myth....
Regards,
Barrie B
b b
cwo...@attbi.com says...
> BEGIN QUOTE:
>
> "One of the "so-called" solutions for multi-battery drain is nothing more
> than a solenoid, a switch that disconnects batteries one from another.
> With a solenoid, there's no multi-battery drain while the batteries are
> disconnected. But the second the solenoid reconnects the batteries, the
> drained battery robs power from the starting battery. That isn't all that
> happens. This sudden violent transfer of energy from one battery to
> another has been known to damage batteries or shorten their life, and
> overheat wires and connections. And worst of all, cause fires. The
> solenoid is no solution for muti-battery drain!"
>
> END QUOTE
>
> Now of course the Sure Power people might not be telling the truth. Or
> perhaps they are simply wildly exaggerating. After all, they sell
> solid-state battery isolators, so perhaps we should not be surprised when
> they attack the solenoid solution. But does this mean there isn't a word
> of truth in the Sure Power claims? I don't know. I'm not a battery
> engineer. But it certainly makes me wonder. Which is why I asked the
> question, here on the list, if using a regular solenoid can cause damage to
> the batteries.
>
>
There is no real world truth in that advertising. The "Sudden violent
transfer of energy" just does not happen unless one of the batteries is
defective, with a shorted cell. This is not a normal occurence. I wonder
if they define the 300-400 amps normal starter drain as "sudden even more
violent transfer of energy"? I'm sorry, but the evidence does not
support that advertising claim....
Regards,
Barrie B
Tom J
<jhn...@hal-pc.org> wrote in message
news:3cdcae02...@news.hal-pc.org...
> On Fri, 10 May 2002 12:47:57 -0700, Chris Wolf <cwo...@attbi.com>
> wrote:
>
> ----clip----
> >
> >I've heard that it can be as high as 7/10ths of a volt. Either way, it
can
> >result in your batteries not getting fully recharged, and failing
> >prematurely.
>
> Wrong
I agree with that. My trailer batteries were lasting an average of 6
years using the diode isolator. It's going to be interesting to see what
happens with this Ford I bought that has a built in relay and wiring to do
all that. I haven't dry camped with it yet, but I'm waiting to see if the
batteries are fully charged at the end of the day like they were when I
was useing the old truck with the isolator.
>
> Apparently there are ways to correct this voltage drop
> >problem, but the solenoid looks like a simpler solution to me.
>
> Wrong
I agree with that also. The isolator I bought in 1996 that was on the old
truck, delivered 2 tenths more voltage to the trailer battery than it did
to the truck battery. The terminals on the isolator were specificatly
labeled which was the alternator, engine battery, and coach battery
terminals. Maybe some have been wiring the isolators into the system
wrong.
Tom J
Will Sill
these words:
>Ahhh, now I see the source; self serving "float the ghost" advertising.
>There is no real world truth in that advertising. The "Sudden violent
>transfer of energy" just does not happen unless one of the batteries is
>defective, with a shorted cell. This is not a normal occurence. I wonder
>if they define the 300-400 amps normal starter drain as "sudden even more
>violent transfer of energy"? I'm sorry, but the evidence does not
>support that advertising claim....
Naturally, you are completely right. But you have to understand
there are folks out there who see a "documented source" and
uncritically accept it as gospel - provided, of course, that they want
to believe it. These are the kind of people snake oil peddlers
depend on to survive. No doubt all of us are a little gullible on
some issues, but some seem determined to swallow lies big enough to
choke a killer whale.
Unfortunately for us all, the bozo asking about this issue has been
told the equivalent of the above information several ways - but of
course all by people he views as morons.
Hey, that's the way it is in usenet!
Society is always taken by surprise at any new
example of common sense. [R W Emerson]
Will KD3XR
Will Sill
relays as follows:
> . . . The isolator I bought in 1996 that was on the old
>truck, delivered 2 tenths more voltage to the trailer battery than it did
>to the truck battery. The terminals on the isolator were specificatly
>labeled which was the alternator, engine battery, and coach battery
>terminals. Maybe some have been wiring the isolators into the system
>wrong.
Many seem unaware there are at least two broad categories of "diode
isolators" (BTW a relay or "solenoid" is also a form of isolator)
1) A single diode that passively prevents juice from flowing to coach
battery from chassis (starting) battery. This type is very simple
but WILL typically exhibit a voltage drop.
2) A dual diode system where BOTH batteries get juice from diodes, and
the regulator looks downstream of said diodes to set the alternator
output level. (OK, that's an over-simplification but the point is
that voltage drop is not an issue with this type.)
One of several reason I prefer the relay deal is that it doesn't
interfere in any way with the vehicle systems.
John S
bnbUNDER...@a1above.net.USE_forUNDERSCORE says...
> I am still looking for the source of the "damaging surge" myth....
>
> Regards,
> Barrie B
b b
Don't you love it? Some guy asks for information then says you are
wrong.
I wonder if he works for the "solution for a non problem" company.
John
jhn...@hal-pc.org
You got to make up your mind fella.
You stated that all the explanations people gave you is not what you
asked for and just wanted the answer. I gave it to you and now you
want to argue because I didn't spend 30 minutes writing again what the
majority on this thead had already given you .
A number of us get hundred of dollars an hour for consulting and have
spent many hours on your little problem only to get stiffed.
See where you have bought the smart solonoid.
From your comments, (lack of understanding of the problem and
solution(s)) I'd advise you to go to a shop that installs them and
pay the price to get installed properly.
May your battery(s) never run down and your wife wake you each
morning with a fresh cup of hot coffee :-)
Erin go bragh
Big John - KR5K
On Fri, 10 May 2002 23:37:10 -0700, Chris Wolf <cwo...@attbi.com>
wrote:
>jhn...@hal-pc.org writes:
Jon Porter
"Will Sill" <wi...@epix.net> wrote in message
news:8h0qdusmt21blr3j7...@4ax.com...
I'll bet that ambulance pulled more juice and put a greater load on it than
a trailer battery would. But I would still use a solenoid made for the
purpose.
Chris Wolf
>>In article <gn5odu0c37of93eci...@4ax.com>,
>>cwo...@attbi.com says...
>>
>> I've heard that there are "smart solenoids" being manufactured that do not
>> activate until the current exceeds 13 volts (i.e. the engine is running).
>> Then the solenoid switches on, and the house battery is switched into the
>> charging circuit. This strikes me as the very best solution of all. I
>> will see what I can find.
>Chris - This idea of a "smart solenoid" is just added complexity and
>entirely unneeded for any simple dual battery setup. Just more stuff
>to break!
Perhaps, but there are people who claim otherwise, and their claims sound
just as reasonable as yours. Since I'm not in a position to decide who's
right, I think I will be conservative and use a Smart Solenoid that
completely eliminates the possibility of battery damage.
Besides, if it breaks, the only thing that will happen is that my house
battery won't get recharged. I can probably live with that.
>In fact, as I stated in my other post, it may do more harm than good
>because of the high solenoid switching current when energized after
>the engine is revved up. The maximum alternator output current of
>today's big alternators is typically well over 100 amps!
My Smart Solenoid is rated to handle 100 amps continuously. I will check
to make certain my alternator does not put out more than 100 amps.
>With the simple solution, the good battery does NOT significantly
>charge the dead battery so there is no problem!
I never stated that the problem was the good battery significantly charges
the dead battery. I doubt that it has time to do so. My concern is the
possible damage caused to the batteries by suddenly connecting a good
battery to a bad battery. Some people (such as the folks at Sure Power)
claim that "this sudden, violent transfer of energy has been known to
damage batteries or shorten their life." Now maybe that's just marketing
hype, but maybe there's something to it. Since I'm not in a position to
judge, I'll just play it safe and use my Smart Solenoid to completely avoid
the problem.
>This is
>easily verified by measurements as well as theory and I have done
>it both ways.
>If it ain't broke, don't fix it.
Well, the Sure Power people disagree with you. And so does Gary Bunzer,
the RV Doctor. In one of his columns, he wrote:
"Considering the sophistication level of today’s state of the art
batteries, I am not a proponent of this older solenoid method. I am a firm
believer that the two distinct 12-volt systems should be kept separated at
all times. In addition to the solenoid and the isolator, a third type of
battery separation is accomplished by the use of "smart" devices such as
Hehr Power Systems Model 10-97 Smart Isolator and Sure Power Industries
Models 1315 and 1314 Smart Solenoids. These devices incorporate a high
capacity, electronically controlled solenoid within a well monitored
charging system. The Sure Power Smart Solenoid comes in two varieties; one
begins charging the auxiliary system only after the engine battery has
reached a minimum 13.2 volts."
Now maybe these people know nothing, and maybe you are absolutely right,
but I have no way of knowing. And until someone cites definitive proof
that the old style solenoid solution doesn't harm batteries, I will have no
way of knowing.
>> I would have thought that some smart electrical engineer would have written
>> up a detailed analysis of the various ways to handle the battery separation
>> question, with a listing of the pros and cons for both methods, but I sure
>> haven't been able to find one so far.
>We EEs do not work for free - Do you?
On the Internet, when someone asks me a question, sure. It helps build my
reputation. That's the whole idea of the Internet. Free exchange of
information. If you want to get paid, get a job.
I have searched the Internet high and low, looking for a web page that
compares the various methods of battery separation, along with their pros
and cons. I cannot find such a writeup anywhere. Which is very
surprising, since I figured that some electrical engineer would want the
credit for being the first to do so.
Over in the ultralight world, I buoyed my reputation quite a bit by writing
up detailed instructions on how to disassemble and reassemble a Bing 54
carburetor. Amazingly enough, no one had ever done this before, even
though the Bing has been around for years. I was glad to do it, even
though I didn't get paid for doing it.
jhn...@hal-pc.org
Someone said "You can't argue with a fool". Guess they were right :-)
Big John - KR5K
jhn...@hal-pc.org
Chris don't want facts. Just don't really know what he wants except to
argue. He may not really have a 'problem'?
Big John - KR5K
jhn...@hal-pc.org
You can't say it any clearer.
Big John - KR5K
On 11 May 2002 13:17:28 GMT, djos...@aol.commnet.net (David Osborn)
wrote:
Chris Wolf
>"Chris Wolf" <cwo...@attbi.com> wrote in message
>news:hkvodussalb6oj099...@4ax.com...
>> BEGIN QUOTE:
>>
>> "One of the "so-called" solutions for multi-battery drain is nothing more
>> than a solenoid, a switch that disconnects batteries one from another.
>> With a solenoid, there's no multi-battery drain while the batteries are
>> disconnected. But the second the solenoid reconnects the batteries, the
>> drained battery robs power from the starting battery. That isn't all that
>> happens. This sudden violent transfer of energy from one battery to
>> another has been known to damage batteries or shorten their life, and
>> overheat wires and connections. And worst of all, cause fires. The
>> solenoid is no solution for muti-battery drain!"
>>
>> END QUOTE
>It's a non-problem. The solenoid closes when the ignition is switched on and
>the alternator is running.
That's how the Smart Solenoid works. The solenoid doesn't close until the
system voltage rises above 13 volts, when the engine and alternator are
already running. But I believe an ordinary solenoid closes the instant you
turn the ignition key, before the engine can start. It's at this point
that one battery could surge into the other, and perhaps cause damage.
>The alternator provides more than enough juice to
>power the vehicle and charge both batteries. The cranking battery doesn't
>get drained at all in this case, so there's no extra damage.
I find it hard to believe that the cranking batter doesn't get drained at
all. But nobody ever claimed that the damage (if any) comes from draining
the battery, but rather from the sudden, violent transfer of energy when
the two batteries are suddenly connected. And that argument sounds
reasonable to me. I can't prove it, but until someone can disprove it, I
must give serious consideration to it.
>If you wan't assurance that your charging system isn't draining one battery
>to feed another, then go with a diode isolator, which is specifically
>designed to prevent that. I've been using Isolators for years with no
>battery destruction problems. People have been doing likewise with
>soleniods, which are pretty much isolators with moving parts.
I considered the diode isolator, but ended up going with the Smart
Solenoid. The Smart Solenoid strikes me as a simpler system, with less to
go wrong. If the diode isolator fails, both batteries will be cut off from
the alternator, and neither will be able to recharge. If the solenoid
fails, only the house battery will be unable to recharge, but the starter
battery will be unaffected.
Chris Wolf
>On Fri, 10 May 2002 19:31:03 -0700, Chris Wolf <cwo...@attbi.com>
>wrote:
>
>>So I have decided to adopt a conservative solution, and use a Smart
>>Solenoid that only joins the two batteries together when the engine and
>>alternator are actually running. Then I don't have to worry about any
>>possible damage to the batteries, with one battery trying to charge the
>>other whenever the ignition key is turned on.
>>
>>I don't much care to pay $100 for a lousy solenoid, but until I see
>>definitive proof that an ordinary solenoid causes no damage to the
>>batteries, I consider it to be cheap insurance.
>To be honest, I had never even considered the damage you described. I
>agree that what you say makes sense, although my limited experience
>doesn't seem to support it.
My experience is also limited, however my house battery recently dropped
dead after only about a year of use. And it was never deeply discharged.
And I have the ordinary solenoid setup. Made me suspicious, so I went
looking for a possible cause. That's when I found the claims, by some,
that the ordinary solenoid can cause battery damage. So I thought I would
check with this newsgroup, and see if anyone knew for sure.
Some people have responded with good arguments, and that I greatly
appreciate. Others have simply claimed, "There's no problem, and anyone
who says differently is a bozo." I listen to the first; ignore the second,
since claims without evidence are meaningless.
>I've had an AGM house battery for a couple of years. It's connected to
>the chassis battery via solenoid, and I've never given a second
>thought to the possibility that it is being damaged because of it.
>
>I'll let you know how long it lasts...
Fair enough. I'll let you know if I have any problems with my Smart
Solenoid.
John S
cwo...@attbi.com says...
> Perhaps, but there are people who claim otherwise, and their claims sound
> just as reasonable as yours. Since I'm not in a position to decide who's
> right, I think I will be conservative and use a Smart Solenoid that
> completely eliminates the possibility of battery damage.
Much of this was offered in a very detailed explanation of how
batteries and charging systems interact from both a theoretical basis
and from a practical standpoint based upon measured data.
In the real world, claims and proof are two different things.
> Well, the Sure Power people disagree with you. And so does Gary Bunzer,
> the RV Doctor. In one of his columns, he wrote:
> "Considering the sophistication level of today’s state of the art
> batteries, I am not a proponent of this older solenoid method. I am a firm
> believer that the two distinct 12-volt systems should be kept separated at
> all times. In addition to the solenoid and the isolator, a third type of
> battery separation is accomplished by the use of "smart" devices such as
> Hehr Power Systems Model 10-97 Smart Isolator and Sure Power Industries
> Models 1315 and 1314 Smart Solenoids. These devices incorporate a high
> capacity, electronically controlled solenoid within a well monitored
> charging system. The Sure Power Smart Solenoid comes in two varieties; one
> begins charging the auxiliary system only after the engine battery has
> reached a minimum 13.2 volts."
Yep - So a company selling a product makes an unsupported and
undocumented claim. Then a writer with no technical education or
abilities quotes this company's sales pitch.
And this is important to you?
Engineers like myself and others have told you that there is NO
large surge current in both theory and MEASURED data.
What do you use for a brain?
John
David Osborn
>But I believe an ordinary solenoid closes the instant you
>turn the ignition key, before the engine can start.
The solenoid isn't energized when the engine is cranking. The normal starting
sequence is to insert the key and immediately turn it to the cranking position.
Therefore, there's no concern about current flowing from one battery to the
other.
> It's at this point
>that one battery could surge into the other, and perhaps cause damage.
What damage is caused? You keep referring to some type of mysterious damage,
but you've never identified what it is -- or if it even exists!
>But nobody ever claimed that the damage (if any) comes from draining
>the battery, but rather from the sudden, violent transfer of energy when
>the two batteries are suddenly connected. And that argument sounds
>reasonable to me.
What "sudden, violent transfer of energy"? Have you ever observed it? Do you
know how big it is? Do you know what it does?
>I can't prove it, but until someone can disprove it, I
>must give serious consideration to it.
You should be giving "serious consideration" to whether or not it even exists.
If it does, then you -- or somebody else -- should be able to prove it exists.
If neither you nor they can prove it exists, then you shouldn't give it
"serious consideration."
David Osborn
>My experience is also limited, however my house battery recently dropped
>dead after only about a year of use. And it was never deeply discharged.
>And I have the ordinary solenoid setup. Made me suspicious, so I went
>looking for a possible cause.
The most likely cause is a faulty battery. There's absolutely *no* evidence of
widespread -- or even narrowspread -- battery problems when an "ordinary
solenoid setup" is used.
>That's when I found the claims, by some,
>that the ordinary solenoid can cause battery damage.
So far, you found *no* evidence that those claims are accurate, now have you?
>So I thought I would
>check with this newsgroup, and see if anyone knew for sure.
The answers you've received clearly indicate that several of us *do* know "for
sure" that the "ordinary solenoid setup" does *not* cause battery damage!
Chris Wolf
>>Chris Wolf wrote:
>>
>> There are very good reasons why you don't use a momentary contact solenoid
>> in an application that requires a continuous-duty solenoid. Why on earth
>> would you want to take the risk of burning up the solenoid?
>Everything I do is a risk. In this case, I decided to try to try a cheap
>starter solenoid (since I don't hold to the theory that you get what you
>pay for), and it never blew. I've still got it, but I don't use it
>anymore.
You're lucky you didn't start a fire.
>So what we have here is over a decade on a starter solenoid, and about 5
>years on nothing at all, I've had no problems with a vampire battery
>sucking all the juice out of my truck battery, or smoking anything. In
>between, I tried a 50 amp diode from Radio Shack. Regardless of the much
>hyped voltage drop, I had no problem with that, either.
There are people who smoke cigarettes all their lives and don't get lung
cancer. But that doesn't mean it's safe.
>So do what you want, buddy. It ain't my money, and I rarely spend more
>money than I have to on the basis of some theory.
Have you considered taking up skydiving, and jumping with only one
parachute? Why waste money on a reserve parachute?
Chris Wolf
>Chris
>
>You got to make up your mind fella.
In your case, it didn't take me long.
>You stated that all the explanations people gave you is not what you
>asked for
Never said any such thing. In fact, I thanked the people who took the time
to offer detailed explanations. Please learn to read.
>and just wanted the answer. I gave it to you and now you
>want to argue because I didn't spend 30 minutes writing again what the
>majority on this thead had already given you .
The sad part is, you probably believe that's really true. Perhaps you are
dyslexic?
jhn...@hal-pc.org
----clip----
I 'punched' once over Greenland on 8 December 1969 in the middle of a
snow storm.. One chute. Worked like designed and saved my life.
I assume you use two condrums as if one is good then two are better
( I call that the double rubber approach)?
Are you going to put two of your fancy relays in to prevent one
failure stopping you?
And you'all have a nice week end (and mothers day).
Big John - KR5K
jhn...@hal-pc.org
Ask a stupid question, get a stupid answer.
Please smarten up. I'm assuming you at least have a GED?
Big John - KR5K
On Fri, 10 May 2002 23:41:42 -0700, Chris Wolf <cwo...@attbi.com>
wrote:
>jhn...@hal-pc.org writes:
>
>>>On Fri, 10 May 2002 13:05:57 -0700, Chris Wolf <cwo...@attbi.com>
>>>wrote:
>>>
>>>----clip----
>>>
>>>. I'd be delighted to find out that I was wrong.
>>>
>>>----dlip----
>
>>Your wrong.
>>
>>Big John - KR5K
>
>Jesus, what a moron!
Chris Wolf
>Will
>
>Chris don't want facts. Just don't really know what he wants except to
>argue. He may not really have a 'problem'?
>
>Big John - KR5K
Son, if you get any dumber, your IQ is going to go negative.
Did you and Will Sill come out of the same batch of illiterate hillbillies?
jhn...@hal-pc.org
Glad you jumped into my conversation with Barrie.
If he gave you such good advice why did you continue to argue with
him? Only an idiot (a stupid person: an utter fool, per dictionary)
would do that.
To end this thread.
1. I hope the smart relay blows up and:
Shorts out your alternator.
Destroys your engine battery.
Destroys your MH battery set.
Blows up your Frig.
Blows out your TV.
Blows up your A/C
etc.
2. If you haven't heard of "KISS" then go and do your homework and
follow proven guidelines developed through years of trial and error.
(You may of course just want to 'keep up with the Jone's' so go spend
your money, you can't take it with you)
And may your wine have all turned to vinager
Us Irish have the ability to cast a spell. Yours is cast.
We don't suffer fools.
Big John - KR5K
On Fri, 10 May 2002 23:44:41 -0700, Chris Wolf <cwo...@attbi.com>
wrote:
>jhn...@hal-pc.org writes:
>
>>Barrie
>>
>>I don't think you can win with Chris? You give him excellent advice in
>>a clear concise manner and he says he is not an engineer and then
>>wants to argue with you????
>
>Actually I thanked Barrie for his good advice. Learn to read, Moron.
jhn...@hal-pc.org
Lots of luck
I've found through the years that you can't argue (and win) with a
zero.
Big John - KR5K
On Sat, 11 May 2002 18:25:10 GMT, John S <camper1...@yahoo.com>
wrote:
Chris Wolf
>In article <s3qodu47md0ucjsp8...@4ax.com>,
>cwo...@attbi.com says...
>> And that is what I ended up doing. Using a single relay to charge both
>> batteries. However I decided to spend a little more money on the relay,
>> and get one of the "Smart Solenoids" from Sure Power. It has a computer
>> chip to monitor the voltage of the system, and it only connects the house
>> battery, via the solenoid, when the system voltage rises above 13 volts
>> (when the engine and alternator is running). This gives me the simplicity
>> and reliability of a solenoid, but guarantees that the two batteries are
>> never tied together, except when charging. So I will never have to worry
>> about damaging the batteries by connecting them before the alternator
>> starts to charge them.
>I'm glad you found the right answer for you.
>
>Does the "Smart Solenoid" have a way to connect a switch so you can force
>the solenoid to close if the starting battery needs a boost from the
>house battery to start the engine? This is a really nice feature that I
>do occasionally use.
Yes it does. It also has a connection for an indicator light, to tell you
when both batteries are connected. I could have used such a feature a few
months ago when I accidently bumped my switch, connected both batteries
together, and spent the night drawing down both sets of batteries. With
predictable results in the morning. Sigh.
Chris Wolf
>cwo...@attbi.com writes (in part):
>
>>So I have decided to adopt a conservative solution, and use a Smart
>>Solenoid that only joins the two batteries together when the engine and
>>alternator are actually running. Then I don't have to worry about any
>>possible damage to the batteries, with one battery trying to charge the
>>other whenever the ignition key is turned on.
>That's an elegant -- and expensive -- solution to a simple problem. The
>starting battery is *designed* to deliver large current flows for a few
>seconds. After all, when the engine is started the battery delivers a few
>hundred Amperes to the starter.
Very true.
>Therefore, we know that it won't be damaged by
>whatever current it supplies to a discharged battery.
That does not necessarily follow. It's only true if the starter, and a
discharged house battery, are electrically equivalent, at least as far as
the starter battery is concerned. And I don't know if they are. Given
their very different natures, I would be surprised if they are electrically
equivalent. Just because a huge flow of current from the starter battery
does not harm the battery, does not guarantee that the starter battery
won't be harmed when it discharges into the depleted house battery.
I'm afraid you're rationalizing in this case. Only experimental data will
show the truth. You can't just measure one factor, like current flow, and
assume that there will be no damage. Battery technology is more
complicated than that.
In any case, even there is no damage being done, why would I want my
starter battery discharging into my house battery? That's just wasting my
starter battery.
>Furthermore, the Smart
>Solemoid does *nothing* to prevent a large current flow to the discharged coach
>battery -- it simply delays the start of the flow by a few seconds. Therefore,
>we know that it can't prevent any damage that might occur to the coach battery.
I'm afraid you're rationalizing again. The idea is to prevent the current
flow from the starter battery, but permit the current flow from the
alternator. The Smart Solenoid does this just fine.
Apparently you are assuming that the current flow into the house battery is
the same from either the alternator or the starter battery. I have no idea
if this is true, but there are people who disagree with you. So until you
can prove your claim, I have no choice but to give it equal consideration
to the claims from the other side.
>>I don't much care to pay $100 for a lousy solenoid, but until I see
>>definitive proof that an ordinary solenoid causes no damage to the
>>batteries, I consider it to be cheap insurance.
>If years and years of experience by thousands and thousands of people isn't
>enough "definite proof" for you, then go ahead and purchase your expensive
>"insurance" against a non-problem!
I'm afraid that "years and years of experience" doesn't prove anything.
It's just anecdotal evidence. Given the fact that many batteries are
routinely destroyed by mishandling by their owners, I would not necessarily
expect that people would be aware of problems with the standard solenoid
system. How many people know how long a battery is supposed to last? Very
few, I wager.
If anecdotal evidence is enough for you, that's your privilege. But I
insist on knowing for certain. And until I know for certain, I will take
precautions. If I'm wrong, I'm only out a little money. If you're wrong,
you could end up stranded, far from civilization.
Chris Wolf
I wish I could simply take your word on that, but I'm afraid I can't.
Unless you can cite hard evidence that you're right, and the other side is
wrong, I have to give both claims equal consideration. Sure Power may be
lying through their teeth, or exaggerating, but you may be uninformed as to
the actual nature of the problem. I have no way of knowing.
You seem to assume that it doesn't matter if the starter battery discharges
into the starter, or into the house battery. I will have to have hard
evidence before I can simply accept that as gospel.
I suppose I could ask Sure Power to back up their claim that the solenoid
can cause battery damage. Might be interesting to see what they say.
Chris Wolf
>b b <bnbUNDER...@a1above.net.USE_forUNDERSCORE> recently wrote
>these words:
>
>>Ahhh, now I see the source; self serving "float the ghost" advertising.
>>There is no real world truth in that advertising. The "Sudden violent
>>transfer of energy" just does not happen unless one of the batteries is
>>defective, with a shorted cell. This is not a normal occurence. I wonder
>>if they define the 300-400 amps normal starter drain as "sudden even more
>>violent transfer of energy"? I'm sorry, but the evidence does not
>>support that advertising claim....
>Naturally, you are completely right. But you have to understand
>there are folks out there who see a "documented source" and
>uncritically accept it as gospel - provided, of course, that they want
>to believe it.
Except that I have never accepted the Sure Power claims as gospel. I've
never even said I agree with them. I simply treat it as an unsupported
claim. Just as I treat your claim that the solenoid causes no problems, as
an unsupported claim.
>These are the kind of people snake oil peddlers
>depend on to survive. No doubt all of us are a little gullible on
>some issues, but some seem determined to swallow lies big enough to
>choke a killer whale.
>
>Unfortunately for us all, the bozo asking about this issue has been
>told the equivalent of the above information several ways - but of
>course all by people he views as morons.
Your problem, Silly Willy, is that you ask me to believe your claims,
without hard proof, and not believe Sure Power's claims. But your claims
are no better than theirs. Without hard evidence to back up the claims,
both sides are simply making empty claims.
Apparently you think that citing your own personal experience, and the
experience of a few others, is sufficient to prove your point. Which only
goes to show that you haven't a clue as to what constitutes evidence or
proof. You obviously have the mentality of a shade tree mechanic who has
no idea how to research and evaluate an issue.
In other words, Son, you're too stupid to participate in this sort of
discussion.
In my case, I'm faced with conflicting claims, with no way to resolve them.
So I will err on the side of caution, and use a solution (the Smart
Solenoid) that totally avoid the risk.