question

shedman avatar image
shedman asked

Temperature compensation when charging

Hello, I have a 24v off grid system running 6x 455w panels split into 3 pairs in parallel connected to 3x 100/50 victron mppt charge controllers connected into common network. Recently I have added a victron 500a shunt with temperature sensor fitted, I have noticed the battery absorption voltage has increased from 28.80 to 29.30, and float voltage has increased from 27.20 to 27.50 (lead acid battery 495 amp) which is higher than battery manufactures given voltages, could this be due to the temperature sensor fitted to the shunt and what would be the expected increase/ decrease in voltage to temperature charge compensation +/-

Best regards,

SmartShunt
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2 Answers
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snoobler answered ·

If you have temperature compensation enabled, temperatures lower than 25°C will result in higher absorption/float voltages. Temperatures higher than 25°C will result in lower absorption/float voltages.


Based on your 24V battery likely needing a temp compensation of about -60mV/°C, I would estimate the temperature at the time you observed those voltages to be about 17°C.


If you have Lithium batteries, you need to disable temperature compensation.



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shedman avatar image
shedman answered ·

snoobler, thanks for the reply, was not sure what the temperature compensation was to the voltage.

best regards,

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