Is A Battery Isolater Required for the Trailers Auxiliary Battery

Question:

If I don’t wire isolation relay in as long as I disconnect plug from trailer will not drain my battery . Is there any other safety I need in line so doesn’t back feed or do anything to truck battery . Also I have electric brakes can I wire them into aux battery or do I need the separate battery for that

asked by: Rich M

Expert Reply:

In regards to the trailer's auxiliary battery, this will be connected to the tow vehicle's battery via a charge line. This charge line will then be tired in with the tow vehicle so that a charge is either emitted constantly or only when it receives a trigger from the accessory circuit. If the trailer's auxiliary battery is lower than the tow vehicle's battery then a charge will be carried out over the charge line but only during one of the above two scenarios. Therefore, the trailer could be plugged into the tow vehicle without equalizing the charge. This will again be dependent on how the tow vehicle is wired. That said, you should not need any additional circuit protection as the trailer charge line should have this built-in.

In regards to the trailer's electric brakes, these will not be wired to the trailer's auxiliary battery at all. The breakaway however would need a power source. The Hopkins Engager Push-To-Test Trailer Breakaway Kit part # 20099 is what I recommend as it comes with everything that you need.

I have attached a trailer wiring help article for you as well.

expert reply by: Conner L