Of all the environmental factors, temperature has the greatest effect on the charge of the battery and its discharge behaviour. The reason lies with the electrochemical reactions that depend on temperatures and occur during the electrode electrolyte interface, which are regarded as the very heart of the battery. If the temperature drops, the value of the electrode reaction also decreases. If the battery voltage remains constant but the discharge current drops, then the battery power output will also decrease. The opposite effect occurs if the temperature increases, namely, the battery power output will increase.

Temperature also affects the speed of the transport process within the electrolyte and its porous electrodes. A rise in temperature speeds up the transport processes and a drop in temperature slows them down. The charge/discharge performance of the battery may also be affected. The higher the temperature, the greater the rate of self-discharge will be, and vice-versa.

The effects of relative humidity will depend on the battery system. These play a key role in “open” battery systems (in contrast with closed battery systems).

Especially, extreme heat causes the water in the battery electrolyte to evaporate. Additionally, heat speeds up the corrosion of the positive battery grid. In the long term, these conditions will adversely affect the service life of the battery. Avoid sing or storing a battery at high temperatures.