Using Trailer Mounted Battery to Power Both Winch and Break-Away System

Updated 11/22/2014 | Published 11/06/2014

Question:

I am adding a winch to a car trailer I own. The trailer currently has a battery breakaway kit with charger. I am adding a traditional RV/Marine battery on the trailer to operate the winch. Can I eliminate the small battery for the breakaway kit and use the RV?Marine battery instead? If so should I wire in the charger with the RV/Marine Battery?

asked by: Greg K

Expert Reply:

You can use a large marine battery to power your winch as well as the breakaway system, people do it all the time. However, it's not the best practice. You can connect the marine battery to the 12-volt accessory feed from the 7-way, but the circuit doesn't have enough capacity to charge a dead or nearly depleted battery.

So, lets say you run down your battery from using the winch, didn't get around to recharging it using shore power, and your battery is nearly dead. Per DOT regulations, your breakaway system needs to be able to hold the brakes on full for a period of 15 minutes. The best-case scenario is that you'd get a ticket if you happened to be pulled over. Worst case, your trailer could break loose and somebody could get hurt if your break away system didn't function correctly because the battery was dead or nearly so.

It would be safer to use a separate battery for the breakaway system.

expert reply by: Mike L