Roll starting EFI car
cs3...@ux1.cso.uiuc.edu
>I have a related question, my wife left the lights on on our Honda
>Civic Si. The battery was drained flat, the computer forgot all its
>learning it did to fine tune the car etc... we had to jump start it
>from another car. The question is, if there is no voltage from the
>battery, can a EFI (Fuel injection) car be roll started? My first
>guess is no as there is nothing running the fuel pump and to tell
>the injectors to open.
If your battery is *completely* dead (i.e. 0V across the terminals),
you are right, push starting will not work with EFI. But it is
more common for the battery to just get weak in "current capacity"
while maintaining 12V across the terminals with little or no load.
Since the starter requires *lots* of current and the EFI stuff doesn't
require much, push starting can still be of help in such cases.
David Doudna "Injection is nice, but I'd rather be air-cooled."
d-do...@uiuc.edu
Terry Laskodi
>
>>I have a related question, my wife left the lights on on our Honda
>>Civic Si. The battery was drained flat, the computer forgot all its
>>learning it did to fine tune the car etc... we had to jump start it
>>from another car. The question is, if there is no voltage from the
>>battery, can a EFI (Fuel injection) car be roll started? My first
>>guess is no as there is nothing running the fuel pump and to tell
>>the injectors to open.
>
>If your battery is *completely* dead (i.e. 0V across the terminals),
>you are right, push starting will not work with EFI.
Well, another related story: last summer, a friend and I went on a
road trip, and he left his car (which used to be my old car) in my garage;
unfortunately, he left the radio on, and when we got back, the battery was
COMPLETELY dead. We tried push-starting the car, but no go. So we left the
car on the street in front of my house, and I borrowed my neighbor's battery
charger, and that did the trick.
What was interesting is that my neighbor said that cars with electronic
ignition need a little charge in the battery to work, and if the battery is
completely dead, you can't push start the car. True or not?????
william hunt
With a 0V battery (i.e. no battery) you can not push start any spark
ignition engine, since there will not be any spark voltage. The
alternator will not generate any voltage either since it is
boot-strapped by the battery. However, most "dead" batteries will
reach 8-10V once the loads have been removed for a few minutes. EFI
and Electronic ignition take more voltage to work than breaker type
ignition (points). If you do not have a least 8V with the ignition
key on, you probably will not get an EFI car push started.
Willie Hunt
Steve Kaess
work with.
--
Steve Kaess at The Black Cat's Shack (Fidonet 1:109/401)
Internet: Steve...@f123.n109.z1.fidonet.org
UUCP: ...!uunet!blkcat!123!Steve.Kaess
Bob Hale
I have a dual battery system in a vehicle; one battery serves the
normal automotive loads while the other is used for two way radios,
searchlights, etc. On three occasions I have made the mistake of
leaving significant (~5 amp) loads on for long durations. The first
time that this happened I noticed that the auxiliary battery only had
about half its capacity available after a full charge. The second
time that I ran it down all the way it only had about 10% capacity.
AFter the third time you could watch the pilot lights on the
equipment "fade to black" in about 2 seconds after a full charge.
None of these experiences caused me any trouble starting because
the two batteries are isolated when the engine is off.
Unless your engine uses a magneto for ignition you do need some
battery voltage to get a spark and make it run. You also need
some battery voltage to get output from the alternator; the
field winding is energized from the battery line (through the
regulator to ground) and there usually isn't enough remanent
magnetism to get usable output with no current in the field.
Yes, it is VERY hard on a car battery to run it down all the way.
The next time I need a battery for auxiliary service I will get
a deep drain battery (such as are used in motor homes).
Bob Hale ...!ucsd!btree!hale
619-535-3234 ...!btree!ha...@ucsd.edu
Jeff Wabik
> yes, you will not get a spark unless the ign. module has some power to
> work with.
This might be a stupid comment (and I'm sure you'll tell me if its 8^),
but... As the engine is turned as a result of the push, wont the alternator
also turn and generate current which can be used for the ignition module?
Sure.. You're not going to have much current, but, how much do you need?
-Jeff
cs3...@ux1.cso.uiuc.edu
Written 12:27 am Mar 6, 1990 by jwa...@uc.msc.umn.edu in rec.autos.tech:
> This might be a stupid comment (and I'm sure you'll tell me if its 8^),
> but... As the engine is turned as a result of the push, wont the alternator
> also turn and generate current which can be used for the ignition module?
> Sure.. You're not going to have much current, but, how much do you need?
Just one problem, most alternators require current to be running
through the field coils if they don't have permanent magnets.
If no battery, you have a chicken/egg kind of problem. :-)
So again, push starting can be effective with even extremely weak
batteries, just not DEAD ones.
David Doudna "Injection is nice, but I'd rather be air-cooled."
d-do...@uiuc.edu University of Illinois at Urbana-Champaign
Jonathan E. Quist
Not stupid at all. The problem is that the alternator will put out
little (if any) current at extremely low speeds (though generators
are much worse in this regard). If you could roll
down a long, steep hill (steep enough to keep moving once you
pop the clutch, regardless of whether the engine starts), then
this would make a difference. In general, it will not.
--
Jonathan E. Quist INTERACTIVE Systems Corporation
j...@i88.isc.com Naperville, IL
{amdahl|att|masscomp|sco|sun}!laidbak!jeq
Jeffrey Mulligan
>Running a typical car battery down completely is very bad for it.
>On three occasions I have made the mistake of
>leaving significant (~5 amp) loads on for long durations. The first
>time that this happened I noticed that the auxiliary battery only had
>about half its capacity available after a full charge. The second
>time that I ran it down all the way it only had about 10% capacity.
This sounds like what happens when you leave your lights on; over
the last few years I have done this three times that I can remember
offhand, twice forgetting to turn headlights off on rainy days,
once leaving a dome light on for a whole weekend while parked in an
airport lot.
What I am noticing now is that my battery is a little wimpy when it comes
to turning the engine over in starting. The battery is charged, at least
to the extent that the dash ammeter doesn't record a lot of charging
current (I know the alternator is working). Interestingly, it doesn't
always seem like a typical weak battery: if the engine doesn't fire
the first time, sometimes the second try will be stronger than the first!?
The battery has been in the car for something over four years, so it may
be nearing time to replace it anyway, but Bob Hale's posting intrigued me:
is a battery's lifetime reduced in big increments as a result of leaving
lights on or somesuch, and/or do they also degrade more or less linearly
over their lifetime?
In my own case, when should I replace this battery?
What about those battery additives?
--
Jeff Mulligan (j...@aurora.arc.nasa.gov)
NASA/Ames Research Ctr., Mail Stop 239-3, Moffet Field CA, 94035
(415) 604-3745
william hunt
When you let your car battery discharge completely, irreversible
chemical changes take place. Your battery "remembers" that it was
treated badly and will never be as strong as it was before. Adding in
chemicals will not reverse the plate damage that occurs. Your best bet
is to replace your battery, or carry jumper cables and hope someone
will be around when it dies.
Willie Hunt
Roger Fradenburgh
One of those seldom used but much appreciated when needed gifts
I received some years back is a battery hydrometer that measures
the specific gravity of the electrolyte in each cell. Accompanying
directions give a brief explanation on how to interpret results.
When *my* 4-year old battery began to have trouble turning the engine
over, a quick check with the hydrometer showed that one of the cells
was nearly kaput, which left no doubt it was time to go battery
shopping.
I'm not certain about prices, but I believe hydrometers can be had
for well under $20. Of course, if you've got one of those sealed,
maintenance free" batteries, then "never mind!"
Michael Thomas
>
>What I am noticing now is that my battery is a little wimpy when it comes
>to turning the engine over in starting. The battery is charged, at least
>to the extent that the dash ammeter doesn't record a lot of charging
>current (I know the alternator is working). Interestingly, it doesn't
>always seem like a typical weak battery: if the engine doesn't fire
>the first time, sometimes the second try will be stronger than the first!?
This happens because the battery heats up a bit on the first try. The
warmer the battery, the greater the power output. (however, batteries stored
hot will deteriorate quickly.)
>The battery has been in the car for something over four years, so it may
>be nearing time to replace it anyway, but Bob Hale's posting intrigued me:
>is a battery's lifetime reduced in big increments as a result of leaving
>lights on or somesuch, and/or do they also degrade more or less linearly
>over their lifetime?
Basically, for about the first 20 cycles, the decrease in performance is
linear. Once you go past this, the battery's performance will decrease
rapidly. A graph of this is in Paul Vincent's Modern Batteries.
%
C 1 |*
A .8| *******
P .6| *
A .4| *
C .2| *
I .1 ***
T 0|______________*
Y | 10 20 30 40 50
|Cycles
>In my own case, when should I replace this battery?
Until the battery will not pass the test. Many automotive stores will
test the battery for free(AutoZone, Western Auto do). Take you battery out
once a year, trickle charge it & then have it tested or get a battery
hydrometer--it should read b/t 1.210 & 1.260 for a fully charged battery.
Trickle charging will help remove some of that yellow sulphation which
is what kills your old battery.
>What about those battery additives?
NEVER--they may improve performance for a little while, but in the end, they
will accelerate the breakdown of the battery. All of the required
"additives" are already in the battery.
Michael Thomas
Tulane Univ. NO LA
Harold Wong
>
>>Running a typical car battery down completely is very bad for it.
>
>>On three occasions I have made the mistake of
>>leaving significant (~5 amp) loads on for long durations. The first
>>time that this happened I noticed that the auxiliary battery only had
>>about half its capacity available after a full charge. The second
>>time that I ran it down all the way it only had about 10% capacity.
>
I have a related question. J.C. Whitney (automotive mail order firm)
sells a product called VX-6 (cat # 17PA1205N) which claims to dissolve
sulfation (number one cause of battery failure) in batteries. They
say it will disolve and prevent it from reforming and good in new and
old batteries. To prove that the stuff really works, they've even said
to try running the battery down (with VX-6 installed already) till the
engine won't start, wait three minutes and start the car.
Anybody know anything about this product? I've dealt with this company
before and they seem reliable.
Harold
-------------------------------------------------------------------------------
Harold Wong (213) 825-9040
UCLA-Mathnet; 3915F MSA; 405 Hilgard Ave.; Los Angeles, CA 90024-1555
ARPA: h...@math.ucla.edu BITNET: hgw%math.ucla.edu@INTERBIT
David Lesher
>through the field coils if they don't have permanent magnets.
>If no battery, you have a chicken/egg kind of problem. :-)
This is one of those MFAQ questions. The answer is "it depends"....
If the alternator core has enough residual flux, it can self excite
enough to make enough lines of force to make more output to make more
lines, etc. It is not only feasible, but often happens. I've done it,
on alternators being run off of lawn mower engines-no battery in
sight.
If your battery is not 0-volt flat, it's even easier. One way you can
help *this* situation is to shut off the load (forgotten headlights, or
whatever), sit for a few minutes, then push the car.
Which does NOT say that this will work every time. Your mileage may
vary. Void where prohibited. Rebate depends on dealer participation.
etc,etc,etc. Maybe there is not enough residual flux left in the field.
Maybe you cannot spin the alternator fast enough. Maybe Old Man Murphy
had his eye on you, all week, just *waiting* for you to screw up.
Or you might just have a car with a slushpump with no rear turbine (do
ANY of them, any more?) in which case, you be F.....
--
A host is a host & from coast to coast...wb8foz@mthvax.cs.miami.edu
& no one will talk to a host that's close............(305) 255-RTFM
Unless the host (that isn't close)......................pob 570-335
is busy, hung or dead....................................33257-0335
Peter Sheriff
The answer is yes and yes. Yes the battery does loose efficiency
slowly over its lifetime. The plate material loosens and falls as a sludge
to the bottom of the battery case. Lead sulphate forms on the battery
plates over the years and reduces the effective plate area. There are
probably many more causes of battery degradation but the effect is a
slow (hopefully) death.
Allowing a battery to drain completely certainly accelerates the
degradation. Plates can buckle and short out. Plate material is lost
at a greater rate. If the sludge builds up to a high enough level and
reaches the plates it can short out the cells. I'm sure that an expert
on the subject can name many ways in which deep draining affects a
battery.
You can change a battery when you first notice slow starter operation
and dimming lights etc. or you can wait until the car won't start at all.
Some service stations can test your battery for a small fee so this may
be the way to go (don't go to a place that will try to sell you a battery
though ((conflict of interests))).
I tried a battery additive to try and get another season out of an
old battery. It only cost a couple of bucks (fortunately) but it was a
waste of money. At that price, you could try it. You haven't got much to
lose and it may work for some batteries.
Pete