AGM batteries

Jonathan Wilson

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Mar 12, 2008, 2:35:41 AM3/12/08

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First, if this is not the right place to ask this question, please tell me
where I should post it.

After doing some research I'm considering using AGM batteries for my
storage.

Does anyone have a recommendation about the most cost effective size and
type to get?

Any suggestions on the best place to purchase from would be appreciated too.

Thanks,

JW

yoyo

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Mar 14, 2008, 10:57:23 AM3/14/08

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JW;

AGM is best used in a mobile application. Are you in a marine or Rec Veh?

John

Jonathan Wilson

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Mar 15, 2008, 12:13:37 AM3/15/08

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yoyo wrote:

> JW;
>
> AGM is best used in a mobile application. Are you in a marine or Rec Veh?

No, I first received a recommendation to use AGM from a friend who heard it
from another fellow with a PV array.

From all the information I've come across, AGMs are the best low-maintenance
deal.

For example when searching the web I found this article, and thought it
sounded pretty convincing: http://www.wagonmaker.com/newbatt.html

My best "excuse" for wanting to use AMGs is, I don't want acid leaks, and I
don't want to have to be constantly monitoring water levels in the
batteries.

Yoyo: is there anything about AGMs that you don't like?

In other words, do you have something you think would be better suited for a
stationary installation?

If there's something "bad" about AGMs, I'd sure like to hear about it.

Thanks,

JW

Tony Wesley

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Mar 15, 2008, 12:23:43 AM3/15/08

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On Mar 15, 12:13 am, Jonathan Wilson <j...@news.cnntp.org> wrote:
> yoyo wrote:

> If there's something "bad" about AGMs, I'd sure like to hear about it.

Cost?

bea...@gmail.com

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Mar 15, 2008, 12:59:44 AM3/15/08

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AGM and Gell batteries can be very effective. Both do have draw backs
in that people are told that they are maintenance free. This is
untrue. Even the simple act of charging is "maintenance".

Maintenance free also means that you can't do the maintenance you can
do on ordinary lead acid batteries. That is topping up the water when
it is depleted. This means that you must follow a much stricter
charging regime to insure that the batteries do not reach a point
where they "gas off", because if they vent off, the material lost
cannot be recombined within the battery and the capacity and life of
the battery is compromised.

Being aware of this and using appropriate charging parameters, such
batteries can offer good life expectancies.

yoyo

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Mar 15, 2008, 2:28:28 AM3/15/08

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On Fri, 14 Mar 2008 23:13:37 -0500, Jonathan Wilson wrote:

> yoyo wrote:
>
>> JW;

>>
>> My best "excuse" for wanting to use AMGs is, I don't want acid leaks,
>> and I
> don't want to have to be constantly monitoring water levels in the
> batteries.
>

OK, AGM seems to be what you want. Another advantage is they can be left
unattended for longer periods as might happen in a vacation cabin or a
boat in storage.

> Yoyo: is there anything about AGMs that you don't like?
>

Nothing more than the cost and the charging regimen as others have
already mentioned. Generally lower voltage but higher current with the
result they can be charged faster so long as they are not overheated.
There is an automotive variety made by Optima that can be charged with
normal automotive style charging systems.

HTH;
John

NoMad

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Mar 17, 2008, 6:09:38 PM3/17/08

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"Jonathan Wilson" <jw...@news.cnntp.org> wrote in message
news:47d779e5$0$582$6e1e...@read.cnntp.org...

AGM batteries are generally used for standby applications. Automotive
applications are generally considered a standby application since no deep
cycling takes place normally.

For daily deep cycling applications AGM batteries have some problems:

1: Cells can't be equalized without over charging and outgassing.

2. If one cell gets low or fails all cells in that string get overcharged
and may fail.

3. No way to check the state of charge of individual cells.

4. Takes 6 months to reach a reliable full state of charge when new.

5. One loose connection in parallel setups can cause unequal usage and
battery mismatch. String with loose connection can become sulphated.

Be careful with your AGMs.

NM

You

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Mar 18, 2008, 1:48:14 PM3/18/08

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In article <frmq7c$9pb$1...@registered.motzarella.org>,
"~~NoMad~~" <nomad...@gmail.com> wrote:

> 3. No way to check the state of charge of individual cells.

Hmmm, apparently you have never seen a Battery Impedance Meter.

Solar Flare

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Mar 18, 2008, 4:10:36 PM3/18/08

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Impedance does not reflect state of charge and the two are not related.

"You" <y...@shadow.orgs> wrote in message
news:you-38196E.0...@netnews.worldnet.att.net...

Terryc

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Mar 18, 2008, 9:06:21 PM3/18/08

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Jonathan Wilson wrote:
> First, if this is not the right place to ask this question, please tell me
> where I should post it.
>
> After doing some research I'm considering using AGM batteries for my
> storage.

Waste of money.
Basically unmaintainable.
Get deep cycle lead acid batteries.

Bill Kaszeta / Photovoltaic Resources

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Mar 18, 2008, 11:17:55 PM3/18/08

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http://www.licor.com/env/Products/Sensors/200/li200_description.jsp
about $195

Bill Kaszeta
Photovoltaic Resources Int'l
Tempe Arizona USA
bi...@pvri-removethis.biz

Bill Kaszeta / Photovoltaic Resources

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Mar 18, 2008, 11:39:20 PM3/18/08

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Also, a Battery Impedance Meter can not measure individual cells unless
connections are available between cells.

There is a good relationship between cell voltage and cell specific gravity,
providing the cell has been at rest for at least 30 minutes:

Specific Gravity = Cell Open Circuit Voltage - 0.845

But Specific Gravity will not give you % capacity, you need to know the full charge
Specific Gravity for capacity. I do not know if the relationship is linear. And it
changes with aging effects.

Bill Kaszeta

Solar Flare

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Mar 19, 2008, 9:54:03 AM3/19/08

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...and a power vent

"Terryc" <newsfour...@woa.com.au> wrote in message
news:frpp45$34a$3...@aioe.org...