I disconnected my three GP24 standard issue Interstate 12VDC batteries mounted on my trailer tongue last OCT. They have been sitting disconnected using battery switches outside on the trailer tongue over the winter months. I checked them in March and all was great with 12.6 or so reading on my meters. I plugged in my trailer to use for supplying power to the house not too long after that for a thunderstorm that knocked out house power and the batteries did as expected running my inverter supplying 120VAC to the house items. I recharged these batteries back up using my 2KW generator running my trailer allowing the on-board converter/charger to recharge the batteries.
I just checked all three batteries last week and they still look great. These GP24 12VDC batteries were originally installed in late 2008.
Just lucky I guess...
Roy Ken