High Temperature Considerations for Batteries

One of the most detrimental conditions for a battery is high temperature, particularly above 55C, because the rates of corrosion, solubility of metal components, and self discharge increase with increasing temperature. High operating temperature during cycle service requires higher charge input to restore discharge capacity and self discharge losses. More of the charge input is consumed by the electrolysis reaction because of the reduction in the gassing voltage at the higher temperature. While 10% overcharge per cycle maintains the state of charge at 25 to 35C, 35 to 40% overcharge may be required to maintain state of charge at the higher (60 to 70C) operating temperatures.

On float service, float currents increase at the higher temperatures, resulting in reduced life. Eleven days float at 75C is equivalent in life to 365 days at 25C. Batteries intended for high-temperature applications should use a lower initial specific gravity electrolyte than those intended for use at normal temperatures. Manufacturers should be consulted on acceptable temperature ranges for operation of their batteries and on the associated effects of temperature. Nickel-cadmium batteries may be more suitable for higher-temperature applications.