The effect of temperature on battery charging

When the battery is at a low temperature, the activity of each active material is lowered, and the dissolution of lead on the electrode plate becomes difficult, so that it is difficult to replenish after the lead is consumed during charging, and thus the charging current is drastically lowered. When the positive electrode plate is charged at -20 °C, the current is only 70% at normal temperature, while the negative electrode plate is affected by the expansion agent, and the low-temperature charging acceptance is lower. The charging current at -20 °C is only 40% at normal temperature. . Therefore, under low temperature conditions, charging mainly suffers from poor charging acceptance and insufficient charging. Therefore, the charging voltage should be increased and the charging time should be appropriately extended.

When the battery is used in the hot season, there is mainly a problem of overcharging. This is because when the temperature of the battery rises, the activity of each active material increases, the oxygen evolution potential of the positive electrode decreases, and the oxygen evolution potential of the negative electrode also decreases (a negative value decreases). Therefore, the charging reaction speed is fast when charging, the charging current is large, and the required charging voltage is low. To prevent excessive charging voltage, the battery temperature should be lowered as much as possible to ensure good heat dissipation, and it is prevented from being charged after exposure to the sun, and should be kept away from the heat source. .

Practice has proved that improving the low temperature performance of the battery should mainly start from the negative plate. When using at low temperature, the battery should be insulated and anti-frozen, especially when charging, it should be placed in a warm environment to ensure sufficient electricity, prevent irreversible sulfate, and prolong the service life of the battery.

Lead-acid batteries are guaranteed to have a certain service life, which is given at an ambient temperature of 25 °C. Since the voltage of the single-acid lead-acid battery has a characteristic of a temperature drop of about 4 mV per rise of 1 ° C, a 12 V battery consisting of 6 single cells in series has a float voltage of 13.5 V at 25 ° C. When the ambient temperature drops to 0 °C, the float voltage should be 14.1V; when the ambient temperature rises to 40 °C, the float voltage should be 13.14V. At the same time, lead-acid batteries have a characteristic that when the ambient temperature is constant, the charging voltage is higher than the required voltage by 100 mV, and the charging current will increase several times, thus causing thermal runaway and overcharge damage of the battery. However, when the charging voltage is lower than the required voltage by 1OOmV, the battery may be damaged early due to insufficient charging. In addition, the capacity of lead-acid batteries is also related to temperature. Usually for every 1 °C decrease in temperature, the capacity will drop by 1%. Therefore, some vehicle operating instructions stipulate that the user should discharge 50% of the rated capacity in the summer and should charge it in time after releasing 25% in winter.

A practical situation is that lead-acid batteries used daily cannot be used in a 25 ° C environment for a long time. Therefore, various thyristor rectification type, transformer step-down rectification type and general switching regulator power supply type lead-acid battery charger which are commonly used in the sales market are currently available. Since the battery is mostly charged in a constant voltage or constant current manner, it is impossible to meet the technical conditions required for the supplementary charging of the lead-acid battery. Therefore, the vulcanization phenomenon of the lead-acid battery is unavoidable.