opnspaces wrote:
Voltage will fluctuate. So instead of knowing a fixed number focus on the trailer should be within on to two tenths of a volt of the voltage at the tow vehicle battery.
Agree. It could be anywhere from 14.9 down to 12.7 depending on the state of charge of the trailer battery. As a battery charges, it's internal resistance increases. As the resistance increases, the voltage seen will decrease. Add to that the fact that the car/truck has a battery that is also in that charging loop, so battery will act as a modulator and you probably won't see the upper end voltage or the lower end, but will see something in between. If you have a meter on it, you want to see a change in the trailer battery voltage after you hook up and start the tow vehicle. This will tell you things are working and the regulator in the car/truck will determine the correct voltage in the line depending on the charge status of both batteries.
