Do Trailer Brake Magnets Have a Duty Cycle

Question:

How long can 12vdc be applied to the magnet before the windings are damaged? The breakaway cable was accidently removed and left unattended over night draining the two 100AH house batteries. Would his burn up the magnets? I checked the resistance which seems OK but the windings could still have an internal short.

asked by: David R

Expert Reply:

There really is no set 'duty cycle' per se. I've seen magnets that had the wires feeding the magnet completely melt down after receiving that sort of amperage for an extended period of time. In other instances, not a thing happened.

Since the magnet's resistance checked out okay, I'd do a thorough examination of the wires feeding all the magnets as well as the break away switch. If you see any scorched wires at either location, you'll want to replace that component. If the wires and switch pass the visual inspection, plug the trailer in and see if the brake controller 'reads' the trailer or picks up any error codes. If that checks out, do some low speed testing in a parking lot. If everything's working fine, I'd feel confident that everything's still in good shape.

expert reply by: Mike L