Too many AMPS ? break-away emergency switch thru deep cycle battery

TimBuck2 · Apr 17, 2014

I am rewiring a 10K trailer, with electric brakes at all four wheels.

The break-away switch was wired though typical small "Universal" battery that is dead, and the box it was in is caput.

The previous owner added a winch, for which the trailer carries a deep cycle battery. I would rather not have to worry about maintaining two batteries on the trailer.

Is there any reason I can't wire the break-away switch through the deep cycle battery? (aside, or course that I will need to make sure there is a live battery on-board when being towed).

Is there a resistor in the normal brake activation circuit?

My only though is - too many Amps might fry the brakes and/or wires to the brakes.

Thanks,
Tim

msb1766 · Apr 17, 2014

That is how my camper is wired, 12 volt deep cycle battery only.

Soundguy · Apr 17, 2014

TimBuck2 said:
Is there a resistor in the normal brake activation circuit?

My only though is - too many Amps might fry the brakes and/or wires to the brakes.

Thanks,
Tim

Remember.. the brake controller normally is what powers the e-brakes.

during an emergency where the break away becomes active, all it is doing it making bat hot and brake power common.

The brakes will be their own self limiting electrical load. If you left them like that all day. yeah.. I'm sure soemthing would get hot.

Generally worrying about the brake magnets long term lifespan is the LEAST of your concerns when you look back and your trailer is NO LONGER behind your vehicle!!!

jwstewar · Apr 17, 2014

No reason to have 2 batteries, every camper in the world is wired that way and they've been doing it that way for 40+ years at least. I know our 1978 camper was wired that way.

joshuabardwell · Apr 17, 2014

TimBuck2 said:
My only though is - too many Amps might fry the brakes and/or wires to the brakes.

Remember that the load determines the amps. The brakes will only "draw" as much current as they need. It's Ohm's Law. I = V / R. For example, a 10-inch brake magnet might have a resistance of 3.5 ohms. At 12 volts, it will pull 12 / 3.5 = 3.4 amps. This will always be true, no matter how big the battery is or how many amps it is capable of supplying, as long as the battery is putting out 12 volts.

TimBuck2 · Apr 17, 2014

Thanks for the input gentlemen.

Tim

Soundguy · Apr 17, 2014

joshuabardwell said:
Remember that the load determines the amps. The brakes will only "draw" as much current as they need. It's Ohm's Law. I = V / R. For example, a 10-inch brake magnet might have a resistance of 3.5 ohms. At 12 volts, it will pull 12 / 3.5 = 3.4 amps. This will always be true, no matter how big the battery is or how many amps it is capable of supplying, as long as the battery is putting out 12 volts.

Exactly.. load determines amps based on a capable voltage source.