Date:         Wed, 25 Jun 2008 12:14:49 -0700
Reply-To:     Poppie Jagersand <poppie.jagersand@YAHOO.CA>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Poppie Jagersand <poppie.jagersand@YAHOO.CA>
Subject:      Re: Why AGM batts don't last as long as they should
In-Reply-To:  <BAY125-F34DCD45EB30EBE65FAF7A7A0A60@phx.gbl>
Content-Type: text/plain; charset=us-ascii

Actually, this Optima battery has done the same self-discharge over about a month or
two several times the past two years. Happens whenever I go out of town. I bought
a solar charger to keep it topped up, but it is apparently insufficient.

When the van is in regular use I don't have a problem. The external draw is
as mentioned 10-20mA, so quite low and not an explanation.

I re-charged it with a smart-charger set to 8A bulk, and it went through the
three stages without reporting errors. (bulk, absorbtion, de-sulfatation cycling).
Now I have used the van for about a week since I came back and all seems
well.

As you suggest, one cell might be bad (as opposed to all). I use NCd and NiMH
batteries lots at school, and individual cells can have radically different self
discharge curves.

The Diesel westy AFAIK came with a group 41. In the past other than the Optima
I have also used regular and calcium/maintenance free wetcell group 78 by
lengthening the terminal wires. Have to be a bit more careful not to short the grp 78
to the metal engine cover if using the top posts, and the standard battery hold down at the
bottom of the tray no longer fits the notch on the battery.

Martin
--- On Mon, 6/23/08, Dennis Haynes <d23haynes57@HOTMAIL.COM> wrote
A battery dropping to 10 volts without explanation is a sign of a bad cell.
Either a cell is dried out and not producing power or shorted. Either way it
needs to come out of service ASAP.

The alternator is working extra hard trying to charge a 5 cell battery and
localized heating can cuase the battery to burst. Yes it can happen to AGMs.
It will be a dryer mess. At 6 years you have exceeded its typical life so
just let go.

I would suggest a normal strting battery but something larger than the group
41. I believe the Diesels were equipped with group 48 as is typical for the
larger Audi's and Mercedes


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