Emergency Brake Battery Size

[on-a-roll]

We renovated a 74 Argosy trailer. I purchased, new axles, brakes, and a new emergency brake away switch. The switch came with a motorcycle sized battery. Is that ample to pull in my four trailer brakes? How do I test with out having to jack up each wheel, spin the tire, and pull the pin on the brake away switch. And even then there may be enough current to pull in the brakes under a no load situation. What about in the real world stopping of a run away trailer? I have 4 6-volt Lifelines on board. Should I just hook the switch up to those?

[markdoane]

I would not be worried about the battery capacity. Each brake magnet draws about 4 amps at full voltage. Four magnets are around 16 amps.
A typical motorcycle battery can deliver at least 100 CCA, so any motorcycle battery should be OK.
I wired my emergency breakaway switch to the house batteries only because it eliminated a battery and meant one less thing I need to worry about and maintain.

[azflycaster]

The battery just needs to pull an electro magnets (one per wheel) to the inside surface of the face of the brake drum. It is the motion of the wheel (turning) that pulls the brakes to drum surface.

[CBWELL]

Your "breakaway switch" is normally wired directly to your onboard battery system. There is no need to install a seperate battery, because you will have to have a power supply to keep it charged. Keep things simple!!

[AldeanFan]

I have that same system in my car trailer, tiny battery for the brakes.
For a test in a big parking lot I pulled the breakaway cable and tried to move the trailer with my truck.
In 2wd the truck spun the back tires
In 4x4 it dragged the trailer with both wheels locked up.

So I’d say it works!