Towing wiring question

My neighbor bought a used 2000xj with tow pac to pull a 3000
# camping trailer. The camper has two big 12v batteries to operate stuff while camping. The camper dealer folks ran a wire from the car battery to the camper batteries to charge them when the car is running. The wire to charge the camper batteries is hooked directly to the pos terminal of the car battery and has a 20 amp fuse that keeps blowing. To me, this sounds like a half assed way to do it. Any body know how hard it would be to use one of the blank spaces in the power distribution center? Is the power distribution center set up like the fuse box in your house where you can add circuit breaker and a branch circuit?

This should be wired with a battery isolator intended for the purpose. You don't want the trailer batteries to drag down the tow vehicle's battery and the isolator will prevent that. Here's a link http://www.campingworld.com/browse/products/index.cfm?prodID=1869&src=SRCH&tcode=37

Actually, the battery isolator really isn't necessary with a pop-up. There won't be any draw (or relatively little) unless it's opened up.

If your pal is blowing 20 amp fuses, there is probably a short someplace.

ChiXJeff