Heat is the worst enemy of batteries, including lead acid. Adding temperature compensation on a lead acid charger to adjust for temperature variations is said to prolong battery life by up to 15 percent. The recommended compensation is a 3mV drop per cell for every degree Celsius rise in temperature.
SOME FACTS ON THE SUBJECT OF AMBIENT OR OPERATING TEMPERATURE. As a general rule, Banner recommends an operating temperature of max. -40 to +55 degrees Celsius; optimum storage conditions are approx. +25 to +27 degrees Celsius. These criteria apply to all lead-acid batteries and are valid for conventional, EFB, AGM and GEL technology.
If the float voltage is set to 2.30V/cell at 25°C (77°F), the voltage should read 2.27V/cell at 35°C (95°F). Going colder, the voltage should be 2.33V/cell at 15°C (59°F). These 10°C adjustments represent 30mV change. Table 3 indicates the optimal peak voltage at various temperatures when charging lead acid batteries.
Lead-acid batteries will accept more current if the temperature is increased and if we accept that the normal end of life is due to corrosion of the grids then the life will be halved if the temperature increases by 10ºC because the current is double for every 10ºC increase in temperature.
Lead acid batteries typically have coloumbic efficiencies of 85% and energy efficiencies in the order of 70%. Depending on which one of the above problems is of most concern for a particular application, appropriate modifications to the basic battery configuration improve battery performance.
Low temperatures reduce the output of a lead-acid battery, but real damage is done with increasing temperature. For example, a lead-acid battery that is expected to last for 10 years at 77°F, will only last 5 years if it is operated at 92°F, and just a year and a half if kept in a desert climate at a temperature of 106°F.