The problem is I only race a few times a year, so charging it through the truck won't help as it will be dead from sitting in the driveway.

I have a marine battery, just trying to eliminate dealing with it. I always have my generator and battery charger at the track. Does it hurt to run the winch off the battery charger? Does it just give it 12 volts?

The proper thing to do would be to mount my marine battery in a box on the trailer and keep it charged, but I never seem to get that accomplished. LOL