How often to you start dinghy to keep battery charged. Dealer installed towing harness and said cars electrical bypassed but car battery is dead when stopping for gas. It's a Honda CR-V/
The vehicles I have towed have never had that problem. The 2006 PT Cruiser is towed on a steerable dolly, so the ignition does not have to be on to unlock the steering. The 2006 Jeep I used to have had an "OFF, not locked" position in the ignition switch, so the electrical system was not energized when being towed. The 2001 Dodge 4X4 also has the "OFF, not locked" switch position. If, by some strange quirk of fate, I ever happen to get a vehicle that has to have the switch ON while being towed, I will either disconnect the battery or install a charge line from the towing vehicle to the towed so that the battery in the towed does not go dead.
even getting one of those small wattage SOLAR PANELS KITS that sits inside the windshield area would help. They are inexpensive and might keep your towed vehicle battery topped off...
These plug into the 12VDC lighter socket. Be sure the 12VDC socket you are using stays ON all the time - alot of them these days turn off a few minutes after the ignition key is turned off.