Voltage drop measured at Brakes

[1963avanti]

I am having poor braking on my fifth wheeler. I have installed all new drums and brake mechanisms and I have new batteries in the tow vehicle.
My Tekonsha P2 sends out 11.8 volts when manually activated. However, at the wheels I am noticing a max of 9 volts. Is this normal?

I assume that each magnet "steals" some % of the voltage....but is this drop normal?

[Gdetrailer]

C Schomer wrote:
Just before I Gave up on elec drums on my last 5er, I ran another 14/2 down the right side so each side had its own 14/2. There was a lot of drop from left to right from the tiny wire inside the axle? I had 11.5 volts max at the trailer cord J box and 11.0 at each magnet after the change. All that work hardly made any improvement. Craig

Well THERES your problem.

simply adding another 14 gauge wire is not enough difference in line loss to be noticeable.

I ran TWO PAIRS of 10 gauge wire.. That makes a huge difference in line loss.

YES, 14 ga is sufficient to handle the 12A draw of the brake magnets.. BUT it IS UNDERSIZED as far as how much resistance the wire presents over all.

Had you gone to 10 ga wire, I would bet you would have brakes that could slam your face into the windshield!

Resistance KILLS the amount of current available, moving up a few wire ga sizes from the old 14 ga factory standards will make a rather drastic improvement in the trailer brakes.

[Happy_Prospecto]

I ran #8 copper wire from my controller back to the axles on the + wire and #8 back to the axles from the battery negative post. I have just a small amount of voltage drop from the controller back to the axles now. The small gauge wire there previously was the cause of low voltage at the brakes.

[lug66]

Most folks overlook the ground connection. Measures your ground points to include front to rear. Dirt and corrosion build up are resistance to the flow of electricity. You may have to trim a wire and replace connectors to to lower the resistance.

[C_Schomer]

Just before I Gave up on elec drums on my last 5er, I ran another 14/2 down the right side so each side had its own 14/2. There was a lot of drop from left to right from the tiny wire inside the axle? I had 11.5 volts max at the trailer cord J box and 11.0 at each magnet after the change. All that work hardly made any improvement. Craig

[Mandalay_Parr]

Voltage drop is from poor connections and small guage wire.
I would check all connections first.