PM53,
Not being a battery guru, these are just thoughts! I think the prime killer of a battery would be overcharging. If your rig still has the ammeter, you would see a constant charge.
Sometimes the battery compartment becomes coated with a crust from the off gassing battery, and the battery would run out of water. This would be a clue to a overcharging battery.
A bad bridge rectifier (trio) in the alternator will allow the unit to charge, but will also allow the battery to discharge through the shorted diode when sitting.
Discharging, then charging shouldn't be life threatening for the battery, within reason.
I think the tests available at the parts stores for battery health are probably mediocre at best.
A battery that sits for an extended length of time in a discharged state will usually fail prematurely.
I would check for a overcharging situation first.
It wouldn't be a bad idea to have a real automotive electrical shop check the alternator for a shorted diode (?) that might cause a drain.
Stuart
