The battery discharge conditions
Battery discharge current. Generally speaking, it is the discharge rate. There are time rate and current rate for the discharge current of the battery. Discharge time rate refers to the length of time from discharge to termination voltage under certain discharge conditions. According to IEC standards, the discharge rates are respectively 20 hour rate, 10 hour rate, 5 hour rate, 3 hour rate, 2 hour rate, 1 hour rate, 0.5 hour rate, etc. The rated capacity of the battery is expressed in C. The capacity of the battery obtained at different discharge rates will be different.
Discharge termination voltage. The terminal discharge voltage varies with the discharge current. With the discharge, the terminal voltage of the battery will gradually decrease. The minimum voltage that can be used for recharging after discharging at 25 ℃ is called discharge termination voltage. The discharge termination voltage varies with the discharge rate. Generally, the termination voltage of 10 hour rate discharge is 1.8V/cell, and that of 2 hour rate discharge is 1.75V/cell. When the voltage is lower than this value, although a little more electricity can be discharged, it is easy to cause the capacity decline of recharging. Therefore, unless under special circumstances, do not discharge to the termination voltage.
Discharge temperature. The discharge capacity of the battery is small at low temperature and large at high temperature. In order to unify the discharge capacity, the discharge temperature is specified.
The actual capacity of the battery. The actual capacity of the battery reflects the actual storage capacity of the battery, expressed in ampere hours (Ah). Similarly, the greater the ampere hour, the greater the capacity of the battery and the longer the range of the electric vehicle. During use, the actual capacity of the battery will gradually decline. The factors affecting the battery capacity include the structure of the electrode plate, the size of the charge discharge current, the temperature and density of the electrolyte, among which the charge discharge current and temperature have the greatest influence. If the charge discharge current is too large, the active substance on the electrode plate will change on the surface, and the capacity will be reduced a lot. The discharge capacity of the battery varies with the discharge current. The greater the discharge current, the smaller the discharge capacity.
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