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nofinsphil avatar image
nofinsphil asked

SmartSolar 75/15 temperature sensor, temperature compensation

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.

MPPT SmartSolarsmart solar charging behaviourtemperature
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1 Answer
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christern answered ·

I might be wrong but have understood that the Smart MPPTs have an internal temperature sensor which they use in the way that they measure the temperature at the time of start-up every morning and then uses that temperature the whole day. So if the morning is cold they believe the whole day is cold. You could use a Smart Battery Sense and connect it to the Victron "network" and all your smart MPPTs will "listen" to the temperature this unit sends during the day.

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