As long as battery voltage is greater than 2.30 volts per cell, gassing will occur and cannot be
prevented entirely. To reduce the amount of gassing, charging voltages above 2.30 volts per cell
should be minimized (e.g., 13.8 volts for a 12 volt battery).
The operating temperature of a battery should preferably be maintained in the nominal band of
60-80°F. Whenever the battery is charged, the current flowing through the battery will cause
heat to be generated by the electrolysis of water. The current flowing through the battery (I) will
also cause heat to be generated (P) during charge and discharge as it passes through the internal
resistance (Ri), as illustrated using the formula for power in Equation (4-4).
P = I2Ri
Higher temperatures will give some additional capacity, but they will eventually reduce the life
of the battery. Very high temperatures, 125°F and higher, can actually do damage to the battery
and cause early failure.
Low temperatures will lower battery capacity but also prolong battery life under floating (i.e.,
slightly charging) operation or storage. Extremely low temperatures can freeze the electrolyte,
but only if the battery is low in specific gravity.