Battery-Charging Chagrin

Q. We dry camp quite a bit and have a trailer with two 12-volt batteries. Can I connect a battery charger (powered by a generator) to the positive terminal on one battery and to the negative post on the other and charge both at the same time? Would I burn up anything in the trailer?

— G.P., Rawlins, Wyoming

A. I’m assuming that you have them wired in parallel so the total effective voltage is a nominal 12 (not 24) volts. If they are in parallel, you can charge both at the same time with a 12-volt charger.

Regarding your question of burning something up, make sure that the terminals are connected properly, that you don’t make sparks near the batteries (which can cause an explosion of the hydrogen and oxygen present in batteries), that the charger is the right capacity (it should have a charge rate of about 20 percent of the combined amp-hour ratings of the batteries) and that the generator is located so it won’t be a fire hazard.
— K.F.


Ken Freund’s more than three decades of auto-repair experience and 20-plus years of RVing helped him author numerous books and articles on vehicle repair. In addition to RV Clinic and Performance, he writes the Powertrain column in MotorHome magazine. Ken has been a California Automotive VO-Tech and Smog-Test Program Instructor and an ASE-certified Master Automobile Technician.

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