Lithium-ion Battery Charge and Discharge Rate
What is the battery charge and discharge rate?
The battery charge and discharge rate refers to the current value required by the battery to release its rated capacity within a specified time.
It is equal to the multiple of the battery’s rated capacity in terms of data value, and is usually represented by the letter C.
For example a 24AH battery, the 2C discharge current is 48A and the 0.5C discharge current is 12A.
How to calculate the charge and discharge rate?
Generally, the value of the charge and discharge current is usually expressed by the charge and discharge rate.
- Charge and discharge rate = charge and discharge current / rated capacity
For example, when a battery with a rated capacity of 100Ah is discharged at 20A, the discharge rate is 0.2C.
1C, 2C, 0.2C is the battery discharge rate: a measure that indicates the speed of discharge.
The charge and discharge efficiency is also related to C. Under the condition of 0.2C, the charge and discharge efficiency of polymer lithium battery should be 99.8%.
Effect of charge-discharge rate on the performance of lithium-ion batteries
The charge-discharge rate has a great influence on the decay rate of lithium-ion battery performance.
That is, the greater the charge and discharge rate, the faster the battery performance decay rate.
Moreover, when the difference in charge and discharge rate of the battery is too large, the consistency of the battery pack will be exacerbated.
Experiments have proved that charging and discharging at equal rates is an effective means to control battery attenuation, improve capacity utilization, and ensure safe operation of battery packs.
In addition, the charge and discharge rate of the lithium-ion battery determines how fast we can store a certain amount of energy in the battery, or how fast we can release the energy in the battery.
Of course, this storage and release process is controllable and safe, and will not significantly affect battery life and other performance indicators.
Generally,
- a lithium battery discharged at 1C as a standard battery,
- a lithium battery discharged at 2C-10C as a low-rate battery, and
- a lithium battery discharged over 10C as a high-rate battery.