Battery charging in Cargo trailer

stevemorris wrote:
jumper cables

+1

If you run directly from the vehicle battery you are in danger of drawing it down such that it won't start the vehicle. A direct connection is fine if you only use it while traveling. Otherwise use a small generator and a battery charger.

jumper cables

Normally, you would use a small generator to power a battery charger, and carry gas for the generator. Alternative is to use the tow vehicle's engine and alternator, and have gas for the tow vehicle.

If you choose the latter you need a long wire set of jumper cables of decent gauge to carry the amps. Eg, a set of 25 ft #2AWG copper aluminum would be good. Get the kind that is flexible in the cold, and has those big "parrot" clamps.

Most likely have to unhitch and get front of tow vehicle near to the batteries in the trailer even with the longer set of jumper cables.

IMO don't even bother with a 7-pin with a fatter wire for #4 pin. You won't get nearly enough amps for a pair of 6s.

Needing other than solar to recharge your trailer batteries indicates to me either bad batteries or an inadequate solar system.

The voltage regulator in your tow vehicle prevents overcharge, same as it does for the existing starting battery. You need to add a charge line and probably a heavier ground than what your 4 pin has. That's why they make 7 pin connectors. Get rid of the 4 pin or at least add the 7 pin beside it.

#10 40 amp fuse. The trailer battery should have a master fuse already there to protect the trailer side of the wire.

I am driving a ford edge that has a 4 pin flat plug. I will google Anderson connector ( no idea what that is). Sounds warm since I do not wish to eliminate flat plug. If I ran a #10 how much should I fuse that for? And what will keep battery from overcharging?

Well, if he has a 7 pin connector, he'll have a live feed he can use. If he has a 4 pin, he won't.

First question is; how much power are you hoping to get from the vehicle?

Usually, the wire on a 7 pin connector is 10 gauge, max, maybe only 12 gauge. Given the length, and how thin that wire is, I would expect it to be a significant limitation on how much power you can move.

If I wanted to move a lot of power, I'd be using something like 4 gauge conductors, run from the vehicle battery back to the rear bumper, terminating in a pair of Anderson connectors. Similar connectors on the trailer. I'd get a set of jumper cables and mod them to have Andersons on each end.

No need for any device, just unplug the wire to separate the batteries when you are camping.

Oh, and you have to fuse the hot wire on BOTH ends, near each battery.

Just pull #6 wire between the batteries. 60 amp fuse on the tow vehicle near the battery.

Connector:
https://www.etrailer.com/Wiring/Pollak/PK12800.html