I have three separate arrays and three SmartSolar 75/15's charging a single 24v AGM battery bank. Currently I have no temp sensing aside from that provided by the MPPT internal sensors. I set up the charge profiles provided by the battery supplier. However the adopted temperature compensation seems incorrect on at least one of the controllers. The ambient temperature is around 20deg C. Absorption voltage is set to 29.1V -32mV/deg C. However the charge controller is going onto absorption at 28.6V. This suggests that the controller thinks it is ((29.1-28.6)/0.032) = 15.6degC above the nominal 25degC baseline ie 40deg C.
I was wanting to check what temperature the charge controller thinks it is, in case it is faulty (as it appears to be). Any way to check? When I turn off temperature compensation the controllers all switch to absorption at 29.1V correctly.
