W I N T E R I Z I N G B A T T E R Y B A N K S

WHEN RV’s ARE STORED THE QUESTION ARISES, WHAT SHOULD BE DONE TO THE BATTERIES?

Charge Fully Before Storing

Always charge batteries fully before storing. When storing batteries for any length of time it is advisable to use a battery charger with an automatic cut off function. These are sometimes called “trickle or float” chargers. This type of charger will keep up with the batteries self-discharge. Ideally the battery voltage should be maintained between 13.2 and 13.6 volts. If you can’t leave a charger attached, then apply a full charge every 3-4 weeks. Self-discharge is less in cold weather, so the time between full charges can be longer, perhaps 8-10 weeks during northern winters. Batteries which are fully charged won’t freeze in weather typical of the U.S., except Alaska. Batteries that are not fully charged may freeze, and the expansion of the ice can fracture the cases.

Battery Types

There are four types of lead-acid batteries. They are:

- Liquid electrolyte, lead/antimony plate;

- Liquid electrolyte, lead/calcium plate;

- Gelled electrolyte, lead/calcium/tin/plate;

- Absorbed electrolyte, lead/calcium/tin/plate;

Lead-Antimony Batteries

Antimony is a stiffener in the grids of lead plates of deep cycle batteries. While antimony makes the plates stronger, it also causes battery cells to self-discharge more rapidly. Self-discharge has a harmful effect because it creates a hard lead sulfate that crystallizes and ultimately destroys the battery. To avoid self-discharge keep lead antimony batteries on a charger when stored. Be sure to do a full charge at least once a month in very cold weather.

Lead-Calcium Batteries

Batteries made with lead-calcium plates, such as the so called maintenance free types, have low self-discharge as long as the weather isn’t too warm. These batteries can be left fully charged for several months without experiencing sulfating.

Absorbed Electrolyte Batteries

Absorbed electrolyte batteries have most of their electrolyte captured in a fiberglass matte, and because there is no antimony in the grids, self-discharge is quite low. Fully charge the batteries before storing the system for the winter, and apply at least one full charge during winter.

Gel Batteries

Gel batteries have the lowest rate of self-discharge, and can be left for months without a charger attached. Be sure to bring the batteries to a full charge before storing.

Mixed Battery Systems

Many systems have different types of batteries for house and engines. Follow the manufacturer’s recommendations for the type of battery that requires charging during the winter. If you leave a charger hooked up, it’s okay to connect all the batteries in parallel. Be sure to check the charger operation frequently, since it isn’t a good idea to have different battery types connected unless they are being charged.

Don’t Forget Small Loads

Often, there are a number of small loads on the batteries such as clocks, instrumentation and control panel indicators. If you’re going to leave the batteries without a full time charger attached, then it would be wise to disconnect one of the battery leads to make sure that there are no stray loads discharging the batteries. Better yet, for convenience install a battery disconnect switch commonly called a knife switch.