What Happens if you Leave Vehicle Connected to Trailer Wiring with Battery Charge Line

Published 11/05/2018

Question:

My Titan has a 130 amp alternator and I would like to connect it to my trailer to charge the batteries on the trailer and run a fan and small refrigerator when needed that receives less than .4 amps of 120 ac volts 4 amps at 12 volts DC input to the inverter. The 7 pin connector is fused at 30 amps at 12 volts think which should be enough to charge the batteries and run the frig i think My question is how do I prevent the house batteries from trying to start the truck when I am connected? I worry that I could overload the small wires that feed back to the trucks 12 volt distribution system creating a fire hazard. Thanks for your reply

asked by: William V

Helpful Expert Reply:

When batteries are connected to each other they do not try to over charge each other. Basically they seek to balance the voltage between the two batteries. So a battery that's slightly discharged will be charged by a fully charged battery until basically the voltages are equal. You also would not have to worry about the charge wire attempting to start the truck either. People run setups like this for charging trailer batteries all the time without any issues.

expert reply by: Jameson C