I've bought a lot of trailers in my life and one of the first things I've done is do away with those clamshell type wire connectors trailer mfg (all trailer types) like to use. I solder each connection and use a protective wrapping then several layers of electrical tape. This way I get full amps from the controller which is what you should be looking for. Just 12 volts doesn't tell much....one or two strands of the brake wire can carry 12 volts but not the required amps for 100 percent braking performance.