On 2008-02-15, NokNokMan wrote:
Hi all,
I'm just about finished building my utility coal-hauler trailer. (Metal
content? about 300lbs. angle-iron and half an 8" spool MIG wire). Since
this trailer has a GVW of 3500Lbs., brakes are required. I had trouble
determining if a breakaway kit was needed, but all signs pointed to "yes".
So if the hitch somehow falls off and the safety chains fail and I hit lotto
and get struck by lightning, then the breakaway battery will supposedly
energize the actuating magnets in the brakes. My question is this: if I
were to attach everything to my 7-connector wiring connector on the back of
the truck (one wire is for the electric brakes which are connected to a
dash-mounted brake controller) would I fry said controller if I should
happen to yank the lanyard out of the breakaway switch? Assuming that
happened, the twelve volts from the breakaway battery would energize not
only the brakes, but the 12v out from the brake controller itself. I know
the manual says "don't wire this thing up wrong or you'll ruin it". I'm
wondering if a diode between the controller and the breakaway unit would
stop the current from flowing to the controller. If so, what kind? I have
no clue about this sort of thing. Would the diode affect the operation of
the controller? Any help would be much appreciated.

Wire it exactly as the manual says and forget it. I am not sure what
exactly you are concerned with, since the breakaway battery is
connected to truck's 12v on a normal basis.

i