AGM Batteries

[Eric Johnson]

My coach originally came with four 6 volt batteries that provide cat diesel
starting and
coach d.c. power. When they failed I replaced them with four 12 volt Interstate
SRM 24
deep cycle batteries wired in parallel per Blue Bird tech service suggestion.
Awhile later, I
installed a new Stat Power charger. This set up has worked reasonably well but
I find I'm
replacing 1-2 batteries per year due to internal shorts at about $75/battery.
Most likely
cause of the short life is difficulty keeping the electrolyte level up while in
storage. Later, I
added a battery filling system that makes it easier to maintain the levels but
I'm still losing
about 1-2 batteries per year.

I've been looking at AGM batteries and Optima D34M deep cycles are now selling
for
about $150 each. Cold crank amps of the Optimas are 750 vs 550 for the
Interstates I'm
using. I think lifespan of the AGMs should be much better since loss of
electrolyte is
virtually eliminated. I could come out ahead even if they cost twice as much.

I've also considered just installing two AGMs versus the four lead/acid
batteries because
we generally run the generator on the road or when dry camping. We don't use an
inverter. Rest of the time we're hooked up at a campground or on float in
storage so not
sure we need all the battery capacity we've been buying.

Anyone have experience with AGM's in their coach? Has anyone tried reducing the
number
of batteries to see if it causes a problem?

Eric Johnson
84FC35SB in San Antonio