I also have experience with the industrial sized AGM and gel cell batteries.
I mean 48 volts @ 240 amp hours industrial size. These things are now going
for almost $5k each. Back in 2000 Douglas sold us these things with a 3 year
full plus two year pro-rata warranty. Now they are down to 1 year full plus
one year pro-rata and they are fighting me even with the system they
designed and installed. The technology just does not live up to the claims.

Dennis

-----Original Message-----
From: Mike S [mailto:mikes@flatsurface.com]
Sent: Monday, February 12, 2007 7:12 PM
To: Dennis Haynes
Cc: vanagon@GERRY.VANAGON.COM
Subject: Re: Batteries don't die, they get murdered

At 06:28 PM 2/12/2007, Dennis Haynes wrote...
>In the industrial world, a quality flooded battery, properly cared for
>is
>expected to give some 1,200 to 1,500 cycles to 80% DOD.

Sure, if you have room for battery with a 2+ foot dimension. Here's a
deal - buy 6 to get 12 volts -
http://www.fords-mtm.com/battery/deka-MS.htm . That will only add 1100
pounds to your bus.

East Penn Deka ( http://www.eastpenn-deka.com/ )makes flooded, AGM and
Gel batteries in "automotive" sizes. They don't even bother to rate the
flooded batteries beyond 60% discharge where they're rated at 700
cycles. They say that 80%/600 for gel and 80%/200 for AGM is typical.
Since they make and sell all three types, I tend to trust their
relative figures.

Here's how they rate the relative performance of their batteries for RV
use: http://www.eastpenn-deka.com/assets/base/1081.pdf