When we attend tradeshows we are frequently asked the same questions over and over. One of the top ten is “when we store our RV or boat for the winter the batteries are usually dead in the spring even though our Inverter/charger has been plugged in?” Just for the record an Inverter changes DC battery voltage into AC line voltage.
The answer is not always the same but the root cause is usually the on-board inverter/charger float voltage is too high. Most of an RV’s appliances are AC line powered and that power is supplied by the batteries that have been inverted to 120 volts AC. When the appliances are all turned on (Refrigerator, radio, lights, etc.) they must have a full 120 volts to operate. Most inverters have a built-in 12 volt battery charger circuit to supply DC voltage to all the house batteries. When you turn off all those appliances the over-head DC voltage can go as high as 15 volts which will cook a battery.
Most house batteries cannot withstand more than 13.8 volts when in a maintenance-float mode without over charging the electrolyte out of the batteries. If the battery loses its electrolyte you can kiss the battery good-bye! Some inverters can be adjusted to the proper float voltage somewhere between 13.2 and 13.8 volts. If you find that your inverters voltage is not adjustable the safest solution is to shut off the on-board inverter and purchase a Deltran Battery Tender which is designed to safely float those batteries through the long cold winter months.
Deltran Battery Tender products are nominally set at 13.2 volts when in the float mode which is perfect for all RV batteries. Our number one RV charger is the Four Bank which has four independent outputs which will fully charge all four batteries then automatically switch to the maintenance/float mode. All Deltran chargers ensure that the batteries remain warm and cozy but not too warm and cozy.
If you decide not to do anything but shut off the on-board unit you stand the chance of having the batteries freeze. When the battery starts to freeze the liquid inside the battery will expand and usually crack the case which can cause a very expensive mess.
Take care of your batteries through the cold months so you don’t find that your batteries are toast when you try to operate your RV in the spring. There’s nothing worse than having to hear “I told you so!” Don’t forget to check the water in the batteries before putting them away for the winter!