You are seeing the battery voltage jump as charging current is increased or decreased. This is similar to the battery resistance test you've done. The greater the battery resistance the greater the jump. The greater the inverter load current, the greater the jump. It's just Ohm's Law: V_jump = I_load * R_bat
In the video, the voltage didn't seem to jump, but rather ramp over time. If it's really a jump and not ramped, then the charge controller should be OK. Still the CC allows voltage to rise to 14.8V when it's supposed to regulate at 14.4V. As soon as the voltage rises above its set point the CC is supposed to halt all charging current. The CC may have a slow response time.
Sal
BFL13 wrote:
So OP is not imagining things where the voltage jumps briefly when you unload the inverter with the controller at its high set point.
