As a key factor, discharge rate has a great influence on battery characteristics. Therefore, it is particularly important to study the characteristics of LIB at different discharge rates. Battery discharge is the process of converting chemical energy into electrical energy and releasing the energy to the load.
An experimental analysis to study lithium-ion battery cell characteristics at different discharge rates is presented. Based on constant current discharge experiments and hybrid pulse power characteristics experiments, discharge rate effects on cell thermal characteristic, capacity characteristic and electrical characteristic are analyzed.
Maximum 30-sec Discharge Pulse Current –The maximum current at which the battery can be discharged for pulses of up to 30 seconds. This limit is usually defined by the battery manufacturer in order to prevent excessive discharge rates that would damage the battery or reduce its capacity.
Under the condition of discharge rate of 0.5C, 0.8C, 1C, 2C, 3C and 4C, the discharge capacity of the cell is 3312mAh, 3274mAh, 3233mAh, 2983mAh, 2194mAh and 976mAh, which is 3.58%, 4.69%, 5.88%, 13.16%, 36.13% and 71.59% lower than the standard capacity 3435mAh provided by the battery manufacturer.
When a battery is discharged to an extended depth, more energy is released during a single discharge cycle. An increase or decrease in discharge depth, for example, from 2.7 V to 2.5 V, generally has a limited effect on the energy efficiency, as shown in Fig. 9 (c).
Under this special working condition, the change of battery discharge rate will impose considerable influence on battery model’s accuracy, and the discharge capacity of the battery will also change with different battery discharge rates, which will have an impact on the SOC estimation results.