Just installed a 12/50 (120VAC) 1+1 Phoenix IP43 charger in our travel trailer.
We have two BattleBorn 100ah batteries we will charge with it and also use it as a 12V power supply for the trailer's DC loads when not charging. While in power supply mode I plan to leave the batteries turned off (disconnected).
I have the charger set to the factory LiFePO4 setting for charge mode (14.2V Bulk / 13.5V Float). While in charging mode with the batteries connected, the charger works as advertised, pushing right at 50A to the batteries.
When in Power Supply mode with the batteries disconnected from the system the charger works perfect as long as the output is set to 13.35V or less. The voltage does not fluctuate more than 0.01V regardless of DC load.
If I set the output voltage any higher than 13.37V the output voltage starts increasing all the way to 15V regardless if there's a load or not. I confirmed with a volt meter that the output from the power supply was overshooting the set point. I even tried it with the batteries connected and the voltage was still increasing way over setpoint. If I return the output setting to 13.35V or lower it returns exactly to setpoint and remains there.
What could cause the output in charge mode to start climbing when set above 13.37V? I wanted to run our trailer at 13.5V while the charger is in power supply mode, but that's not possible because the output runs up to 15V and remains there.....