View Full Version : trailer battery

Aug. 3, 2010, 07:44 AM
Anyone know if you can charge an electric trailer brake battery with a regular car battery charger? I don't want to blow anything up!:D

Aug. 3, 2010, 08:08 AM
Yes, just make sure it's set to the correct voltage (6 vs. 12) and you put it on "automatic" and not manual charge. Don't even think of setting it to "start".

I use my car charger to keep the mower batteries up to snuff...and they're pretty small also, no problems. Just make sure, if you can, the battery has sufficient water in it.

Aug. 3, 2010, 09:41 AM
My battery is an AGM, so water is not a problem.

I modified the wiring so the battery will be charged when the truck is running.

It also gives me the benefit of being able to run the interior lights even when not hooked up.

Not for long, but long enough to put tack in place for a trip the next day or to look in the trailer for something I can't find and can't remember where I left it.

Yes, you can leave the trailer interior lights on and run the truck battery down, but that is a small thing to remember and much better than having to charge the battery on your own.

Many of the high quality trailers today are wired to charge while the engine is running and even have indicator lights to confirm that the battery is charging.

You can wire to the "only hot when switch is on" side of the harness. That would charge the battery automatically but would not give lights in the trailer except when the switch is on.

I did this when I had an older truck. Switch in run position ran too many things not wanted.

My new truck with the aux position on the switch can eliminate the danger of the battery running down, but it is not worth changing at this point.

Just an idea you might consider.


Aug. 3, 2010, 01:39 PM
My trailer has the emergency battery charging when the trucks hooked up. The battery running the hydraulic lift and lights is also charged when the truck's hooked. Every once in a while I'll plug in the trailer to the truck to keep everything "fresh".