Here’s a brief explanation on how to calculate the temperature compensated adjustments our controllers make to their charging voltages based on the ambient temperature changes.
The charging voltages listed in the controller operator’s manual are specified at a 25C standard test condition ambient temperature with a -.030V (@ 12V battery) adjustment per degree C change in temperature above or below the 25C reference. The (-) in front of the .030V indicates that voltage adjustment is inverse to the change in temperature. In other words, if the temperature increases above 25C, the controller decreases it’s charging voltage by -.030V per degree C rise above 25C and vice versa. An accurate measurement of the ambient temperature is required for calculating the the controller’s temperature compensated adjustment.
Example:
An ambient temperature of 35C = +10C increase above the 25C base temp = 10 x -.030V compensated adjustment = temperature compensated -.300V decrease in charging voltage.
Therefore, a 14.4V charging voltage specified in the manual @ 25C would be reduced to 14.1V @ 35C or increased to 14.7V @ 15C.
The compensation rate is doubled to .060V/C for 24Vnominal battery systems and quadrupled to .120V/C for 48V nominal battery systems.