The new 3500 pound pull Superwinch Terra winches arrived. We welded in some support steel and mounted the winches one on each side. They are wired in series and run on a 12V battery (so technically each winch gets about 6V and runs slower, which it does).
The series wiring worked a treat when raising the door. If one side was slack it quickly catches up as the other motor slows because power is diverted. The door comes up exactly equal on both sides.
Lowering the door is not quite what I expected (but should have). Sometimes one motor will spin a little faster and the other cable will go slack. Not every time, but sometimes. I believe this is because the motors have no load on them when lowering the door. They don't run away and drop the door but one cable holds the weight of the door for awhile while the other unwinds faster. I am not quite sure how to fix this or if I should bother fixing it at all.
It looks a lot nicer and the cables are out of the way. It should be safer because of the redundancy in cable and brake.
