(ET) Battery dilemma

[David Tiefenbrunn <davidtief comcast net>]

I've been running a large frame Elec Trak for years now.

I used to be able to get used golf cart batteries for about 1/3 the cost 
of new ones, and they would work well enough for a few years, so pretty 
good deal.    I used a simple analog float charger to keep them at full 
charge, and used the stock built in charger for the main charging.  A 
few years back, I got a fancy 36V modern charger, but found that it was 
horribly power hungry in idle / float mode, and the float set point was 
too high, boiling water away too fast, and NO adjustment!

 The last set of batteries I bought new Duracells from Sam's or BJ's.  
They are showing low capacity already, only been a year or so.   I've 
been using 3 smart energy efficient 12V chargers to keep them at proper 
float voltage.   Even if I got the expected 5 years under ideal 
conditions for flooded cell lead acid batteries, that's about 6x90= $540 
every 5 years.  Yikes!  And right now, that's not even close to what I 
got..  [I have to go gather data to determine if I have one dead battery 
/ cell / or the whole set is low output]

Contemplating looking at other battery types, or an inverter generator 
with a big power supply [which I have the parts to build laying around] 
to power the Elec Trak.

Dave