by Bogo » Wed May 22, 2013 11:14 am
Recharging the battery from your vehicle while driving is a different issue than the converter. A converter like the Magnetek is made to power 12 VDC equipment while connected to a 110 VAC outlet. Some converters are also made to properly charge batteries.
On a 7 wire trailer harness there is an auxiliary power pin which is often hooked directly to the trailer's battery with only a fuse to protect the wiring from short circuits and overloading. If you plan on doing charging while driving I recommend both the ground and aux wires be 10 gauge or larger. Make sure the ground wires are well connected to the frame AND battery on both the trailer and tow vehicle. Never rely on the hitch ball as a ground return path. Put 30 Amp fuses on the positive aux wires right next to the batteries. This is to protect the wiring against shorts and overloads. The flat blade in the RV-7 connector is only rated for 30 Amps, and chances are the vehicle wiring isn't rated for more than 20 Amps. If you need higher current handling, the round pin contacts in the 7 pin round pin trailer connectors are rated for 40 Amps. It also possible to use a second connector like an Anderson Connector to provide a high current link.
On 30 Amp fuses. Often the individual blade type fuse holders you see in stores are only rated for 20 Amps. Make sure the ones you buy are rated for 30 Amps.