AGM battery charging question

[Damian]

Hi guys,
I would appreciate if I could get some advice on below question.
I have two AGM deep cycle batteries(identical). Thye 6V batteries about
300ah each. I am hoping to connect they on series to get 12V.
My question is that,
Is it safe to charge the batteries connected as above with a single 12V
charger without any damage to the batteries or the charger?!
I am hoping the charger simply treat the two 6V batteries as a single 12V
battery and charge they equally without any issues.
Thank you for any advice.

[Toby Ponsenby]

On Mon, 29 Oct 2012 19:47:30 +1100, Damian blathered:

ummm. AGM Batteries have slightly different characteristics to the
batteries the charger you're considering will work well with insofar as
charging requirements.
I'm guessing here, but IF the batteries are basically equal in their
resistance etc, then 12 Volt chargers might work well enough - depends
on just what actual voltage the charger belts out in response to the
internal resistance of the victim batteries - in other words how well
the charger is 'regulated'. All bets are off with the exceedingly cheap,
brightly coloured and nasty devices laughingly called chargers, commonly
found in the local accessories store right beside the plastic wheel
trims and furry steering wheel covers:-)

We have a few battery experts about this group , hang on, THESE groups.
Will be interesting to see their response.
Natch, my suggestion is that if you actually shelled out 'ard earned
for the batteries, you'd be treating them to a real live computer
controlled tricked up charger.
What do you intend to use this massive power source for, may I ask?


Wow,
--
Toby

[Damian]

Hi Toby,
I am planning to use the two batteries(yes they are massive) on my small
caravan for camping, etc.

I do have a charger which I paid around $50 and which is advertised as a
good maintenance charger for AGM batteries
Here is the link for the charger.

http://www.ebay.com.au/itm/110969221327?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

I also have a good regulated power supply(1V to 24V) which I built years ago
and use as a battery charger as well. By manually manipulating the volatage
and current with control knobs, I have been using it as a maintenance
charger.
Only thing I don't know much about is whether connecting two batteries in
series to gain voltage is good or not. I read that unless the two batteries
are identical in size, condition, etc it's bad news for both batteries. But,
are they really 'identical' even when they are brand new?! That I am not
sure. So, I need some real help.
Thanks
"Toby Ponsenby" <m...@privacy.net> wrote in message
news:1v1cm6f9e1lg5$.yceoz8p0hixr.dlg@40tude.net...

[PeterD]

If the batteries are the same yes, series will be fine. Most
applications (UPSs etc.) they are series and charged as a bank. Before
charging in series you must, however, ensure that each is identical in
capabilities (as well as specifications) and that each has an identical
level of charge.

Any charger to charge an AGM battery must be designed to charge those
types of batteries. You cannot use a generic charger, you need one with
an AGM setting.

--
I'm never going to grow up.

[terryc]

Yes and No.
Yes, it works fine, as long as you have an appropriate charger.
No, you need to make sure they stay as close as possible in voltage.
That said, you should source a 6v charger to sync them from time to time.

[terryc]

On 29/10/12 21:29, Damian wrote:
> Hi Toby,
> I am planning to use the two batteries(yes they are massive) on my small
> caravan for camping, etc.
>
> I do have a charger which I paid around $50 and which is advertised as a
> good maintenance charger for AGM batteries
> Here is the link for the charger.
>
> http://www.ebay.com.au/itm/110969221327?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

Erk. Rubbish. My rule of thumb is that you'll pay a similar amout for
the battery charger as you do for the battery.

>
> I also have a good regulated power supply(1V to 24V) which I built years ago
> and use as a battery charger as well. By manually manipulating the volatage
> and current with control knobs, I have been using it as a maintenance
> charger.

You really need a charger that performes the appropriate stages for your
type of battery.

> Only thing I don't know much about is whether connecting two batteries in
> series to gain voltage is good or not. I read that unless the two batteries
> are identical in size, condition, etc it's bad news for both batteries. But,
> are they really 'identical' even when they are brand new?! That I am not
> sure. So, I need some real help.

Do regular voltage checks and work them monthly or quarterly.

[Toby Ponsenby]

On Mon, 29 Oct 2012 21:29:31 +1100, Damian blathered:

Ok - thought so re the Van - or perhaps a trailable boat.
The trick there is to use one of the new 'innovations' while on the
road.
You don't need monster cables to get sufficient Voltage to the caravan
any more.
There a device on the market which via trickery (OK, an invertor+ a few
bits) which supplies 'correct' voltage to the batteries in the van/boat.
Actually it does heaps more than that. Maybe there's one in the range
that doesn't run a few power sources. Have a dig about on and near this
link.
The important thing is the ability of the thing to FULLY charge your
batteries.

< http://www.batteriesdirect.com.au/shop/product/12569/d250s-dual.html >
Richie would say bloody maarvelos. Really.
--
Toby

[Woody]

This probably explains all you need to know.

http://www.bdbatteries.com/mcharging_procedures.php


--
Woody

harrogate three at ntlworld dot com

[Neil]

On Mon, 29 Oct 2012 21:29:31 +1100, "Damian"

Ok - here's my two pen'orth:

1) The real issue with using two batteries together is when they are
connected in parallel permanently. Connected in series, there is not
really any difference to one battery, i.e. it is still 6 cells
connected in series, just that they are housed in two separate
casings.

2) Is the automatic charger up to the job of charging a 300Ahr
battery? If the spec is the same as the one in that link(350mA) I
seriously doubt it! It might be OK just to leave connected AFTER the
battery has been nearly fully charged at a more practical rate(say 10
to 25 Amps), just to top it off and supply a maintenance charge during
long periods of lay-up.

3) As has been said, the cost of the batteries, and their capacity,
probably justifies a high quality charger designed for such a bank.

4) In time one of the batteries will no doubt develop a faulty cell or
will have lost electrolyte in one of them. But again, this is no
different to one cell going down in a 12V battery - you're still going
to have to replace the bank. Meantime you're just going to have to
regularly monitor your battery bank for terminal votage, because with
AGM sealed units, you don't have the option of measuring the specific
gravity in individual cells(or topping up electrolyte) - which is why
after having used some sealed AGM batteries in the past(and also a
VERY big Gel battery many years ago), for leisure use, I now use a
conventional wet battery with screw caps to each cell so I can
maintain the battery properly.

HTH

Neil

(Reply via group please)

[Damian]

Hi Neil,
Thanks for the information.
Dont they(AGM batteries) suppose to last for 5-10 years without needing any
maintenance(privided it's kept charged properly)?
I thought we pay extra money to get sealed AGM deep cycle batteries because
they suppose to last lot longer than wet cell batteries.
You don't think that's the case?!
Thanks

"Neil" <dono...@thisaddy.com> wrote in message
news:217u88herhv5q3jr7...@4ax.com...

[Damian]

Thanks

"terryc" <newsnine...@woa.com.au> wrote in message
news:k6lsds$8jc$1...@dont-email.me...

[Damian]

Thanks. That link was very helpful.

"Woody" <harro...@ntlworld.spam.com> wrote in message
news:w6Ajs.50951$A%.12439@fx26.am4...

[Damian]

Thank you. I think this is a great product even though it's bit pricy. I
think I'm going get a one.

"Toby Ponsenby" <m...@privacy.net> wrote in message

news:lc51gal9i2yl.r...@40tude.net...

[Toby Ponsenby]

On Tue, 30 Oct 2012 12:32:40 +1100, Damian blathered:

Them's the goods - there may be others out there, as I'm sure there will
be others attempting to compete with the function, which is essentially
a better way to charge remote batteries than previouly existed outside
of uber epensive commercial stuff.
The people who've installed the stuff I linked to are mightly pleased
with it.
Only downside I can see so far is that the device should be in a well
ventilated location. Goes without saying that given what it does,
there'll be a little heat to dispose of.
Additionally the solar cell charging function ain't so redundant soon
given the prive of the PV arrays falling day by day.
--
Toby

[Neil]

On Tue, 30 Oct 2012 12:20:04 +1100, "Damian"
<damian_a...@yahoo.com.au> wrote:

>Hi Neil,
>Thanks for the information.
>Dont they(AGM batteries) suppose to last for 5-10 years without needing any
>maintenance(privided it's kept charged properly)?
>I thought we pay extra money to get sealed AGM deep cycle batteries because
>they suppose to last lot longer than wet cell batteries.
>You don't think that's the case?!
>Thanks
>

Damian,

I don't know whether AGM batteries last significantly longer than
conventional flooded cell batteries, they may well do - do the
manufacturers guarantee them for that long? It would be my guess that
AGMs would last longer than a "maintenance free" flooded cell battery
of similar capacity. The bottom line is that it's a trade-off between
cost and longevity I guess.

I personally prefer to be able to measure the specific gravity of the
electrolyte in the cells in my vehicle, leisure and other lead/acid
batteries, and be abe to top-up if necessary. The battery I have in
my caravan at present is a 110Ah semi-traction battery with big, wide
screw caps to each cell. It's about 7 years old, and showing no signs
of loss of capacity, or deterioration of any cell above any other. I
do occasionally give it an "equalising" charge, and top up the cells
as necessary. It cost me no more than a vehicle starter battery at
the time, and next year it will have lasted as long as my last sealed
AGM battery did, before it's capacity started to fall significantly.

[Damian]

Hi Neil,
I got little confused here.
I would like to follow your advice and purchase a battery.
I personally like the idea of maintaining the battery myself exactly the way
you mentioned.
I thought batteries with screw caps on the top are usualy automotive
starting batteries. And the sealed batteries are the ones usually used for
solar, caravan, UPS, etc. I thought AGM(and deep cycle) batteries are
usually sealed.
Do the semi traction batteries give out Hidrogen gas when it's been charged?
If so, do I need to install in outside the caravan or uder the bonnet like
starting batteries?
How is this semi traction battery different from typical vehicle starting
batteries?
Can you please send me a link to purchase a semi traction battery like
yours?!
I'm in Melbourne, Australia.
Thanks
Damian

"Neil" <dono...@thisaddy.com> wrote in message

news:47jv88lm1ribljghv...@4ax.com...

[Neil]

<snipped>

On Wed, 31 Oct 2012 13:11:01 +1100, "Damian"
<damian_a...@yahoo.com.au> wrote:

>Hi Neil,

>I got little confused here.
>I would like to follow your advice and purchase a battery.
>I personally like the idea of maintaining the battery myself exactly the way
>you mentioned.
>I thought batteries with screw caps on the top are usualy automotive
>starting batteries. And the sealed batteries are the ones usually used for
>solar, caravan, UPS, etc. I thought AGM(and deep cycle) batteries are
>usually sealed.
>Do the semi traction batteries give out Hidrogen gas when it's been charged?
>If so, do I need to install in outside the caravan or uder the bonnet like
>starting batteries?
>How is this semi traction battery different from typical vehicle starting
>batteries?
>Can you please send me a link to purchase a semi traction battery like
>yours?!
> I'm in Melbourne, Australia.
>Thanks
>Damian
>

Damian

First of all, I'm not advising you get a flooded cell battery for your
particularly high capacity requirement - only passing on my own
experience. I do not know what the cost of 300Ah flooded cell leisure
or traction batteries are likely to be. In the UK, capacities of 85Ah
and 110Ah are very popular, hence the price is comparatively low. I
suspect a 300Ah battery would be considerably more expensive than 3 x
110Ah batteries together, but you would have to research that
yourself.

The differences between battery types are basically this:
Leisure batteries are designed for prolonged but light current drain,
e.g. running the lighting, water pump and TV/radio/audio system in a
leisure vehicle. Their life can be shortened prematurely if required
to supply heavy current drain on a regular basis e.g. powering a winch
or motorised motive device(caravan mover etc.) A leisure battery is
classed as a deep cycle battery but to get the maximum life from it,
it should not be discharged to less than 50% capacity.

Traction batteries are designed for electric propulsion and other
higher current drain functions like electric winches. Electric motors
can have very high start-up currents when used for propulsion and
winch use. Again they are classed as deep cycle but the same advice
applies as for leisure batteries regarding level of discharge.
Semi-traction batteries are a compromise between the previous two.

Vehicle starting batteries capable of delivering very high currents
for short bursts, will have a shortened life if used as a deep cycle
battery.

In the UK, both starter batteries and leisure(deep cycle) batteries
can have the same type of screw caps, and can look very similar.
Frequently the larger starter batteries have screw caps that do not
require a screwdriver or coin to remove(my ST battery is like this
also). Some starter batteries have no screw caps at all, and are
described as "maintenance free"( because you cannot carry out any
maintenance).

All AGM batteries are sealed. In order to achieve the gas
recombination, it is necessary that the pressure inside the case be
allowed to rise without venting freely to the atmosphere, hence the
term Valve Regulated(the valve is a safety to avoid the casing
splitting). The biggest application for these batteries is in devices
which will be subject to being used in various different orientations
where a flooded cell would spill electrolyte.

UPS batteries are usually(but not always) sealed AGM or Gel batteries,
because they are intended to be fitted and then forgotten for the
duration of their life expectancy. They would then be replaced,
whether or not they had any capacity left. In the early 70's I worked
in a telephone exchange where the stand-by batteries of which there
were two, were banks of 25, huge open single cells. In effect these
were for UPS, and were regularly maintained by having their specific
gravities measured and entered on a chart. This gave very good
advance warning if one of the cells was beginning to deteriorate.

All lead/acid batteries have the potential to emit hydrogen and oxygen
when they are overcharged. This is actually beneficial when
equalising a battery, but requires the ability to be able to replace
the water lost in so doing. Therefore, flooded cell batteries should
be housed where the gases can freely escape into the atmosphere(and
not into the vehicle interior) before an explosive concentration can
build up. Flooded cells batteries usualy start to gas with a charging
voltage above 14.8V, but with 15.5V quoted for equalising you can see
that gassing is most definitely involved. Caravans in the UK hve a
dedicated compartment for the battery which is sealed from the
interior, and where a venting tube from the top of the battery can
vent any gas produced, directly to the atmosphere outside the caravan.

I don't have any links for you, I got my battery from a local caravan
spares dealer.

[terryc]

On 01/11/12 14:05, Neil wrote:
> I
> suspect a 300Ah battery would be considerably more expensive than 3 x
> 110Ah batteries together, but you would have to research that
> yourself.

125Ah are the largest common Deep discharge wet cells in Aust. Rather
than put tweo in parallel to get larger capacity. I preferred to buy two
6Volt 225 Amphour batteries. that was to prevent the problem of one
failing and pulling down and maybe destroying the other.

Another factor is my ability to lift individual batteries in and out of
locations. I remember that the 12V 125AmpHr batteries weighed 35kg each
Can not remember the figure for each 6V 225Amphour battery.

> The differences between battery types are basically this:
> Leisure batteries are designed for prolonged but light current drain,

> Traction batteries are designed for electric propulsion and other

> Vehicle starting batteries capable of delivering very high currents

My rule of thumb is that if the battery is rated in amphours, then it is
designed for "deep discharge" use. If it is rated in CCA, then it is a
ICE starter battery.

> All lead/acid batteries have the potential to emit hydrogen and oxygen
> when they are overcharged. This is actually beneficial when
> equalising a battery, but requires the ability to be able to replace
> the water lost in so doing.

This is why cheap battery chargers are a bad idea. They do not limit the
final trickle voltage and can run wet cells dry.

> I don't have any links for you, I got my battery from a local caravan
> spares dealer.

I actually go to a battery specialist who originally had traction as
well as alarm batteries but a seems to have moved more to alarm and
specilist motor starters(changing market in the area). Look in yellow
pages, etc for battery supliers in industrial areas and avoid main
street battery shops.

[Damian]

Thanks mate.
The two massive 6V batteries that I mentioned aren't in my hands yet. I have
been considering getting them to maintain a good long lasting power source
for the van. But, now I think it may be an overkill and a pretty heavy job
as well.
I think I am better off with a 125Ah sealed deep cycle battery and may be a
backup one. I reckon it's better to rely on a small generator rather than
carrying massive heavy batteries like I was planning to do.
What do you think about that?

Thanks
"terryc" <newsnine...@woa.com.au> wrote in message

news:k6t0lv$eft$1...@dont-email.me...

[Damian]

Hi Neil,
Thanks for clarifying that for me. I now know lot more about batteries than
I did before. I think I will get a sealed maintenance free battery as it's
bit challenging for me to install the battery outside the van and installing
it under the bonnet is not a choice either as there's no room.
So, I won't be able to get a battery with the ability to maintain like
yours.
I am thinking a maintenance free AGM deep cycle battery(or two). Does that
sounds like a good idea for my application?
Thanks

"Neil" <dono...@thisaddy.com> wrote in message

news:fpk398taqtm3jcvfo...@4ax.com...

[terryc]

On 02/11/12 00:23, Damian wrote:
> Thanks mate.
> The two massive 6V batteries that I mentioned aren't in my hands yet. I have
> been considering getting them to maintain a good long lasting power source
> for the van. But, now I think it may be an overkill and a pretty heavy job
> as well.

You need to look at your power requirements and work them out.
Refridgerator
Lighting
The dooles like mobile phones, torches, the radio(s)(AM/FM/UHF, etc)
(Where did they all come from)
The laptop
The 12 volt TV.
Medical machines.

Even stuff like fans on diesel/gas space heater and/or 12V electric
blanket. Sigh, there is even 12v hair dryers.

When it comes to stuff like aircon, then you need to run a generator of
sufficent size to run it. Add in the microwave to that as well.

Over here, camp sites can be divided into those that allow generators,
where mos caavans go and thse that don't, where most campers go. man
people don't like one destroying the peace and quiet.

> I think I am better off with a 125Ah sealed deep cycle battery and may be a
> backup one. I reckon it's better to rely on a small generator rather than
> carrying massive heavy batteries like I was planning to do.
> What do you think about that?

Batteries and a solar panels are a basic way to go here if you have
light demands like a refridgerator, lighting amd the doodles.. Most
times you will have no problems if you have adequately specced the
batteries to give you a couple of day's requirements.

It is when you are camped for the week, then you can run into problems
from it being heavily overcast all week. I have something like the honda
generator on my plans as a emergency back up.

I have also gone for four days capacity, so that effectively means that
at worst case I only loose the peace and quiet for one day in four.


If you are travelling every day/few days, like doing the big loop, that
C-tek D250S that was linked is the way to go as it tops up your caravan
battery from the solar panels when you're stopped or from the car
alternator when you are travelling. you need an auto isolator that
switches the car feed in after the car alternator has recharged your
starter battery.

OTOH, some places here, it just means that instead of stopping in the
bush camps, you pay for a powered site overnight and charge your
batteries up then.


I'll point out that I'm talking from the Australian perspective where we
have 30 million population spread over an area the size of
Europe/Mainland USA, but mostly in a few big cities and little facilties
in between.

[Neil]

>>
>> I actually go to a battery specialist who originally had traction as well
>> as alarm batteries but a seems to have moved more to alarm and specilist
>> motor starters(changing market in the area). Look in yellow pages, etc for
>> battery supliers in industrial areas and avoid main street battery shops.
>>
>

On Fri, 2 Nov 2012 00:23:31 +1100, "Damian"
<damian_a...@yahoo.com.au> wrote:

>Thanks mate.
>The two massive 6V batteries that I mentioned aren't in my hands yet. I have
>been considering getting them to maintain a good long lasting power source
>for the van. But, now I think it may be an overkill and a pretty heavy job
>as well.
>I think I am better off with a 125Ah sealed deep cycle battery and may be a
>backup one. I reckon it's better to rely on a small generator rather than
>carrying massive heavy batteries like I was planning to do.
>What do you think about that?
>Thanks

Now you're getting the idea!

In fact you don't even need a backup battery if you carry a 12V
charging generator!

I've posted many times about this in the past, and now there are
small, engine driven, alternator charging units(capable of delivering
up to 45Amps charging current), available that will charge your
battery in a very short space of time.

There is one in the UK advertised on eBay as Supercharger, which is
very similar to a unit designed in Aus(but I don't know what name it
is sold under there!).

I have plans to get one of these for myself in the very near future!

[Damian]

Hi Neil,
If I understood you correctly, you meant a mechanical unit similar to the
built in alternator, right?!
I couldn't find any on ebay using the keyword 'supercharger' or 'super
charger'. It shows all the turbo stuff.
Can you please post me a link to that?
Thanks

"Neil" <dono...@thisaddy.com> wrote in message

news:frv598hlp62sq73dr...@4ax.com...

[Neil]

On Sun, 4 Nov 2012 10:12:12 +1100, "Damian"
<damian_a...@yahoo.com.au> wrote:

>Hi Neil,
>If I understood you correctly, you meant a mechanical unit similar to the
>built in alternator, right?!
>I couldn't find any on ebay using the keyword 'supercharger' or 'super
>charger'. It shows all the turbo stuff.
>Can you please post me a link to that?
>Thanks
>

Damian,

Try this:-

www.ebay.co.uk

Put this into the eBay search line

portable generator 50 amp 12 volt

HTH

[Damian]

Hi Neil,
By the looks of it, this is an idependent unit. Basically it is a smart
charger generator, am I right?
I am amazed to see that its available on LPG as well.
I wonder how they manage to compact all that stuff into a small unit. Must
be an ingenious design.
I definitely want to get hold of one.
Only thing I am wondering right now is that where to install this unit.
It's not cheap, but for obvious reasons.
I am sure Chinese clone makers are dismantlng it right now to find out how
to copy it. :))
Cheers
Damian

"Neil" <dono...@thisaddy.com> wrote in message

news:a3gb9893nobbb8od7...@4ax.com...

[Neil]

On Mon, 5 Nov 2012 00:27:15 +1100, "Damian"
<damian_a...@yahoo.com.au> wrote:

>Hi Neil,

>By the looks of it, this is an idependent unit. Basically it is a smart
>charger generator, am I right?
>I am amazed to see that its available on LPG as well.
>I wonder how they manage to compact all that stuff into a small unit. Must
>be an ingenious design.
>I definitely want to get hold of one.
>Only thing I am wondering right now is that where to install this unit.
>It's not cheap, but for obvious reasons.
>I am sure Chinese clone makers are dismantlng it right now to find out how
>to copy it. :))
>Cheers
>Damian
>

It's a vehicle alternator directly coupled to an engine which is a
Korean clone of a Honda GXH50. Honda having apparently stopped
exporting this magic little engine! If you have a look here

http://www.boab.biz/acatalog/Battery_Chargers.html

you can see the Australian version of this unit, at a much higher
price!

Maybe these are available from another source in Oz?

[Damian]

Hi Neil.
I haven't been aware these units are available here.
I'm looking into it right now to find it.
It should be cheaper for locals. I wonder why the Aussie one is more
expensive.
Caravans are expensive here too. UK built ones are usually better quality
and not as expensive as the ones in here. I don't know the reason.
Everything seems to be expensive in Oz right now. :)
Perhaps that's how they kept the economy going witout going into a
recession. :))

Cheers
Damian
"Neil" <dono...@thisaddy.com> wrote in message

news:o31e98t42lvh8nol5...@4ax.com...

[Harry Bloomfield]

Damian brought next idea :

The only difference between a pair of matching 6v batteries and a
single 12v battery, is that the latter is in one package, basically the
cell links are internal. If both are matched with age, present state of
charge, general usage - then no reason why they shouldn't be linked and
charged as a 12v unit.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk