Of all environmental factors, the temperature has the greatest effect on battery charge and discharge behavior. This has relation with the temperature dependent electrochemical reactions occurring at the electrode/electrolyte interface, which may be considered the heart of the battery. If the temperature decreases, the rate of electrode reaction decreases too. Supposing the battery voltage remains constant, the discharging current drops and thus the power output of the battery. The opposite effect occurs if the temperature rises, i.e. the power output of the battery increases.

The temperature also affects the speed of transport processes within the electrolyte and its porous electrode. A rise in temperature accelerates transport processes, a decrease in temperature slows them down. The charge / discharge performance of the battery may also be affected. But if the temperature is too high ( more than 45℃), battery cycle life will short sharply due to the active materials decline and electrolyte exhaust.

Low temperatures (e.g. -15℃) will obviously reduce Ni-Cd and Ni-MH battery discharge rate. At -20℃ electrolyte is at its freezing point, charge speed will greatly slow down. At low temperature (under -0℃) charge will raise the internal gas pressure and probably unseal the safety vent. Ambient temperature of 20±5℃ is the best range to get effective charge. Generally with temperature rising charge efficiency will become higher. But when the temperature rises up to 45℃, the materials performance in the battery will be degenerated and battery service life will be shorten greatly.