We had an old-school Rutland
charge controller on our boat that never worked since we bought the boat. So we ordered a new HRSi controller and fitted it the other day.
Before fitting it I was testing the voltage across the wires coming from the boat batteries. I measured 11.8 volts, which was a bit lower than expected since the digital battery monitor
was showing 12.5 volts, but voltage was still obviously present.
I fitted the new HRSi controller as per instructions, which state that after connecting the batteries to controller, it will sense whether the system is 12 or 24 volts, then the led will light up to show the state of the battery
(red: low charge, orange: almost full, green: full).
However, no led came on. Again with the multimeter I measured voltage across the wires (still connected to the controller) and saw only 2 volts - very strange. Then, oddly, voltage started to slowly climb. Over the course of the next maybe 3 minutes, the voltage climes linearly to over 11 volts and the led on the controller came on!
Does anyone know why this would happen?