Originally Posted by rapiniii
I'll put them in the garage, put a charge on them and switch over to the BatteryMINDer 2012. Supposedly it's keep them topped off, without boiling off the electrolyte, and also desulfate them. Don't know if it will work, this is the first time I've used it.
Yes, they work. I have two different VDC BatteryMinder products and both have extended or resurrected my batteries. I use this one BatteryMinder Battery Tester Maintainer
attached directly to my batteries and it uses the onboard charger to desulphate the batteries (it works on both house batteries though only connected to one).
I use this one BatteryMinder 12248
for lawn equipment batteries. Typically my lawn tractor battery would last a year since BatteryMinder has been used to trickle charge and desulphate I have gone 3 years since I battery change.
On the boil off issue, you have something drawing enough current to make the onboard battery charger to stay in medium or high charge mode. With everything off, check for current draw from the batteries using a DC amp meter.
Even with my house disconnect off I measure about 1 amp draw. In a week that is 168 amps.
Disconnecting the negative is one way to eliminate battery drain caused by small electronics in the coach but even a disconnected stored battery losses power.