Ideal operating temperature for Flooded deep cycle lead-acid batteries is 25°C (77°F).  Battery capacity and cycle life is affected by operating temperature. Operating at higher temperatures will reduce cycle life due to cell degradation.  A cycle life reduction of ~50% for every 10°C over 25°C (77°F) is expected. Loss of cycle life is not recoverable.

Ex. Continuous operation at 35°C (95°F) will typically reduce battery cycle life by 50%. 

Cooler operating temperatures will prolong cycle life. However, low temperatures will reduce

available battery capacity. Capacity is regained as operating temperatures rise.

Operating temperature is considered when sizing a battery bank to meet a required available Amp-Hour (AH) capacity. As continuous operating temperature drops, the required rated AH capacity of the battery bank will increase to meet the equivalent capacity. To calculate the adjusted capacity, use the multiplier in the table below. 

Cold Temperature Capacity Multiplier 

EXAMPLE: Calculated loads require 500 AH usable capacity. With an operating temperature of 25°C (77°F), a battery bank with 1000 AH rated capacity is needed. (max 50% DOD)

1000 AH capacity battery bank with a continuous operating temperature of -10˚C (14˚F) 

1000 AH 1.65 = 1650 AH adjusted capacity.

Note: as operating temperatures may vary considerably over a 12-month period, the average temperature and corresponding multiplier may be used to calculate an adjusted capacity. Cycling frequency, seasonal changes in loads & desired depth of discharge (DOD) should also be considered when sizing a battery bank to meet a required Amp-Hour capacity.