Does Brake Controller Voltage Plus Breakaway Battery Voltage Double to 24 Volts

Published 08/16/2018

Question:

When you wire the break away switch from your trailer battery through the switch and to the blue wire that operates the trailer brakes and you also have power coming from your tow vehicle controller through the blue wire, would that cause an electrical problem if the break away switch is activated and the tow vehicle brakes are activated at the same time. If not, how would it not change to 24 volts or short the system? If so can a relay switch avoid that problem?

asked by: Bob K

Expert Reply:

Two sources of 12 volts applied to the same circuit would not double the voltage to 24 volts. Essentially this wires the circuits parallel to each other so the only thing changed is increased amp hours due to more amps applied. If you were to wire to 12 volt circuits in series instead then the voltage would double to 24 which would cause problems.

I attached a picture that shows the difference between series and parallel wiring.

expert reply by: Jameson C