Date:         Mon, 14 Mar 2011 23:19:40 -0400
Reply-To:     David Beierl <dbeierl@ATTGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@ATTGLOBAL.NET>
Subject:      Re: Auxilliary batteries
Comments: To: Daryl Christensen <daryl@aatransaxle.com>
In-Reply-To:  <001601cbe2b5$56a08730$03e19590$@com>
Content-Type: text/plain; charset="iso-8859-1"; format=flowed

At 10:04 PM 3/14/2011, Daryl Christensen wrote:
>OK…My van charges at about 13.6 to 13.8 or9 max. 
>All the spiffy temp/voltage AGM battery chargers I see are 120V AC input..

Now that I've preached the gospel - and I believe 
every word of it - you have to make your own 
evaluations of first cost vs lifetime cost and so 
forth.  I will seriously state that for someone 
who is going to be actually cycling batteries 
down on a regular basis (or irregular one, for 
that matter), lifetime system cost will be less 
if you do it right, and you'll get much better 
service as well - and the batteries will last 
many years.  But the up-front costs are quite 
high.  And as the DEKA comparison pointed out, if 
you're going to be using them below 32F/0C, use AGM instead of gel.

Conversely if you want to minimize up-front costs 
without *unnecessarily* increasing lifetime 
costs, stick with flooded-cell batteries.  Your 
lifetime costs will still be a lot higher, and 
you'll still get poorer service and you'll have 
to replace batteries more frequently, but the 
flooded-cell batteries are less expensive and 
will take the abuse better than the sealed ones 
of either type, but especially the gel ones.

If you want good service and good battery life 
but want to take the edge off the costs up front, 
pay for the three-stage regulator, use 
flooded-cell batteries and keep track of your 
state of charge with a hydrometer if you can't 
afford an integrating consumption meter.

Yours,
David