Now that I have a larger trailer I need a trailer brake controller. I have ordered the Maxbrake controller that measures air line pressure to brake the trailer proportionally.
The trailer brake controller goes up by the driver of course. How do I deal with sending the current for the electric brakes over 40 feet back to the rear bumper? The total max amps seems to be around 12 amps. Do I really need 4 AWG wire to deal with voltage drop over that distance? The harness on the brake controller doesn't have wire anywhere close to 4 AWG.
10 or even 12 ga will work just fine. More important is to be sure you have a good ground on the trailer. Don't depend on the hitch to provide the ground.
Run the brake ground through the 7 way plug directly to the bus ground. I wouldn't worry too much about the size of the wire. I know with me pulling my car (no aux brakes) that I'm still under the GVW of the bus-as are most conversions (GVW on the bus-36,000lbs. Weight of the bus pulling the car-34,750lbs). The most important thing is to make sure the battery on the trailer is always up to charge and the break away switch works. Don't get me wrong-the brakes on the trailer will always be of help in stopping.
I'm in a barbershop chorus (Masters of Harmony) and head of the pickup truck with fifth wheel (3ax) to pull our risers, suits and props. It has brakes on all 6 wheels and is a nightmare trying to keep them balanced-even after having all the brakes replaced with new linings, magnets and backing plates (kits you can buy). If you're just setting up your trailer, I highly recommend you switch from individual electric brakes to a single electric over hydraulic brake actuator. It is an electric motor actuator attached to a hydraulic master cylinder (just like on your car) on the nose of the trailer, that works the all hydraulic drum or disc brakes on the trailer. Then the brakes are always in balance. For obvious reasons, they are very popular with boat trailers. Electric over hydraulic is by far the most reliable, even auxiliary trailer braking system you could have. Good Luck, TomC