Wednesday, February 1, 2023


New RVer asks: How will my batteries cope with winter?

By Russ and Tiña De Maris

cold batteryNot every RVer uses their rig throughout the year. Some do a winter lay-up and wonder: Just how will my batteries cope with cold weather? Taking care of RV batteries will add to longevity–ignore them and you may wind up replacing come spring.

First, let’s confirm that your rig will be stored somewhere in the lower 48. Alaska (so we’re told) gets frigidly cold in places; if you have an RV in Alaska, your best bet is to bring it (and yourself) south of the 54th.

For the rest of us who stay out of Seward’s Icebox, cold care for RV batteries is fairly easy. First rule: Never store your rig with batteries at anything less than a 100% charge. A fully charged battery won’t freeze, but less-than-full batteries can (and sometimes do). A battery frozen is a battery that expands and can break the casing, ruining the battery and spilling acid causing still more trouble. So hang your charger on your battery and fill ‘er up.

What causes batteries to lose their charge? Two things: A load on the battery, even small, “parasitic” loads like those placed on them by say, an LP gas detector or engine “computer” will with enough time, deplete the battery charge. The second cause of discharge is “self discharge,” meaning that batteries, left to themselves, with time will simply discharge on their own.

Battery loads can be eliminated simply by disconnecting the batteries from their circuit. For “house” batteries that care for non-engine systems, disconnecting the load means loosening and removing the negative cable from the house battery bank. Of course, safety detectors in the coach will no longer work to warn your of any sort of disaster. Disconnecting the SLI (“starting, lighting, ignition”) battery will cause any “trouble codes” stored in your rig’s engine computer to vanish from memory. You may want to have a technician hook up a code reader to verify you have no stored codes–some auto parts stores will do this for free.

Even with batteries disconnected there’s still the issue of self-discharge. Rule to thumb says, the colder the battery, the slower the rate of self-discharge. This means you might be able to come out and hook up your battery charger every few weeks to bring your stored batteries “up to snuff.”

We’re much bigger fans of just leaving the batteries hooked up to their related circuits and hooking a “smart” charger to them. A smart charger analyzes the battery’s needs and charges them accordingly. Once at full charge, a smart charger applies a “float” charge that keeps the battery at the fully charged level, but doesn’t allow for a damaging overcharge.

We have “seasonal use” car that we store away from shore power. When not in use, we have a regulated solar panel hooked up to the battery that keeps the battery topped off. Regulated, because any old solar panel hooked directly to a battery doesn’t have the sense to stop charging when “full” is reached, and the result of overcharging can be fatal to the battery.

The same principle applies to RVs equipped with solar panels. If the rig is stored outside where the panels can find the sun, and the system has a regulator, your “house” battery issues are solved. Getting “juice” to the SLI battery in your motorhome is possible too, but it will require a bit more wiring and equipment to tie it to the solar array.



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