Forum Discussion

kohldad's avatar
kohldad
Explorer III
Feb 10, 2015

Battery Isolator

Need some edumacation and ideas on setting up my new truck and truck camper. On the old truck, I just tied the coach and truck battery together with a 30A resettable breaker and 2 gauge wire. Had a surepower automatic disconnect for a wire until it quit working, but then I switched to just unplugging the camper at night when I was worried about killing the truck battery.

On this truck though, I want to isolate the truck and camper's electrical system. So I don't have to worry about the camper inverter when on shore power messing up the truck's electronics nor the camper draining the truck. But still need to make sure the truck alternator will quickly and adequately recharge the camper battery since I often boondock and can use 20 A/hr per night which needs to be recovered in 3-4 hours of driving.

Would something like the 1202-D Sure Power be the ticket or some other way better?
  • Your choice is admirable, but if you really have No 2 wires from truck battery to relay, and from there to camper battery, you should up your fuse capacity to a better choice for your alternator to be able to provide.

    Hopefully you are saying your overnight use is 20 amphours, and not your hourly use.
  • A simple 100% duty cycle solenoid relay will do the best job and wont cost you any voltage. Relay
    NAPA sells one as well but I couldn't find the P/N for it.
  • You could use something like this relay. Large posts would be for connecting the batteries. Small post would energize the relay from a "hot in run" circuit. These are readily available from most auto parts stores. It is rated continuous duty.
    Battery Disconnect
    You would connect to your truck battery through a circuit breaker to the camper.
    I would stay away from diode based isolators. Some have some pretty healthy voltage drop across them.