Yuo might benefit from a "battery minder", a trickle charger that senses terminal voltage and only charges when the voltage drops to a pre-set level. I've got friends who store bass boats over the winter and they keep their batteries in good condition with those systems. Check Ebay for a good deal on one.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!