Charging toad battery

I ran the red wire from the RV 7 wire connector to a pos. aux. battery connector near the car battery.
We shut off the car engine before I plug it in at the RV, and disconnect before we start the car.
The brake lights on the car from the RV are wired into the separate turn signals acting as brake lights too.
When the Brake Buddy activates it turns on the normal car brake lights, so I have 2 sets of brake lights and no feedback to RV.

Yes you can do that. I use a circuit breaker on the charge line at each end at the battery. Use a 20 amp breaker or fuse if you use #12 wire or a 30 amp breaker or fuse if you use #10 wire. I wouldn't use anything less than #12 wire for a charge line.

Thanks Ken, I hoped that would work, RVi sells a system to charge the toad battery for $50 but I don't know what the difference is except perhaps feed back.

Yes, exactly what we have done. I have a 20 amp fuse very close to the toad battery, in case of any shorts between the battery and connector plug at the front of the car. Never had a problem in 3yrs with the CRV or 3 with the Accord.
Some people will recommend a diode, to prevent feeding back to the MH when stopped, but on the Ford chassis, the power at the back of the MH is disconnected with the ignition off.

Ken