Check the water level in the batteries. Lower levels could cause freezing in really cold temperatures, which leads to cracks in the batteries. Fill the batteries up if necessary.
Remove the batteries from the RV and put them in a warm place. This will eliminate the freezing issue altogether.
Charge the batteries fully. The batteries lose charge during storage, but maintain it longer if charged. Check the batteries' charge about every month. If it drops below 80 percent, recharge the batteries.
Flip the disconnect switch if you are leaving the batteries in the RV. This will help maintain the charge and keep the batteries from being drained if you left any appliances or electrical switches on.
