RV to Car Battery Charger

Anyone installed a line from their PC to dinghy for battery charging ?  Our Honda battery gets enemic after one day of towing with brake system and is usually dead half way through the second day.  Have to remember to run it each night after towing.

I  ran a 10ga wire to mine and change the plug from a ? to a 7.  Only problem I had was feedback and cured that with a diode blocker in the toad.  It has worked well for several trips now and I most times don't turn off the car or the brake system overnight when only staying the night.  Always starts, as far as I can tell, normally for the pre-leaving lubrication, next morning.  Before I put in the blocking diode I ran things down a couple of trips.
Hope this helps.
 
L. G. 

Our secondary braking system has 6 wires from the motor home to the tow vehicle.  One of them is an extra hot wire to the secondary braking system in the tow vehicle, therefore leaving the tow vehicle battery alone.

If your tow vehicle's electrical cable has only 4 wires as most do, you can utilize the RV ignition switched hot wire from the RV connector.  Utilizing power from the RV would require you to either replace your 4 wire cable with a 6 wire, or add a second cable.  Either way, you'll be running the hot wire from the RV to the secondary braking system.  All the wiring modifications are on the cable and tow vehicle, no modifications to the RV wiring because it's right there in back in that big 7 wire round connector.

I just been through all this last July installing a US Gear Unified Tow Brake System.  The Unified installation wiring diagram CLICK HERE should help clarify my description.  The RV hot wire is the red 14 guage wire labelled umbilical cord.  It illustrates a separate 2 wire cable, but I changed my 4 wire to a 6 wire to eliminate the extra cable.