How to Test the Charge Retention Ability and Cycle Life of Lipo Rechargeable Battery?

At present, lipo rechargeable batteries are widely used in mobile phones, computers, digital cameras and other digital products. How to detect the quality of the lipo rechargeable battery we use? We can test from the three aspects of lipo rechargeable battery charge retention ability and charge recovery ability, charge recovery ability after storage, and cycle life. Next, let's learn about the detection method of lipo rechargeable battery.

Ⅰ. Test of charge retention capability and charge recovery capability of lipo rechargeable battery

The test of charge retention capacity and charge recovery capacity is mainly to test the capacity retention of lipo rechargeable battery after being stored for a period of time. Generally, the battery is recharged after the charge retention test to check its capacity recovery. The steps of the charge retention capability test are as follows:

① The lipo rechargeable battery is discharged to the specified termination voltage (usually 3.0V) with a constant current of 0.2C at an ambient temperature of (20±5) °C, and charged to the termination voltage (usually 4.2V) with a constant current of 0.2C. Then it transfers to constant voltage charging (the charge termination current is generally 0.02C).

② The lipo rechargeable battery should be stored in an open circuit for 28d at an ambient temperature of (20±5)℃.

③ The lipo rechargeable battery should be discharged to the specified discharge termination voltage with a constant current of 0.2C at an ambient temperature of (20±5) °C.

④ Calculate the capacity (Ah) released by the lipo rechargeable battery in step ③.

⑤ The charge retention capacity shall be expressed as a percentage of the calculated capacity in step ④ compared with the rated capacity.

⑥ The lipo rechargeable battery should be charged according to step ① within 24 hours after discharging in step ③.

⑦ The lipo rechargeable battery should be discharged to the specified discharge termination voltage with a constant current of 0.2C at an ambient temperature of (20±5) °C.

⑧ Calculate the capacity (Ah) released by the lipo rechargeable battery in step ⑦.

⑨ The charge recovery capacity shall be expressed as a percentage of the calculated capacity in step ⑧ compared with the rated capacity.

Ⅱ. Test of charge recovery ability of lipo rechargeable battery after storage

The charge recovery ability test after storage mainly tests the capacity recovery of lipo rechargeable battery after storage for a specified time. Specific steps are as follows:

① The lipo rechargeable battery is discharged to the specified termination voltage (usually 3.0V) with a constant current of 0.2C at an ambient temperature of (20±5) °C. Then it is charged with a constant current of 0.2C to the termination voltage (usually 4.2V), and finally transferred to constant voltage charging (the termination current of charging is generally 0.02C).

② The lipo rechargeable battery is discharged to the specified discharge termination voltage with a constant current of 0.2C at an ambient temperature of (20±5) °C.

③The lipo rechargeable battery should be stored in the open circuit for 90d under the ambient temperature of (40±2)℃.

④ The lipo rechargeable battery should be charged according to step ① at an ambient temperature of (20±5) ℃.

⑤ The lipo rechargeable battery should be discharged to the specified discharge termination voltage with a constant current of 0.2C at an ambient temperature of (20±5) °C.

⑥ Calculate the capacity (Ah) released by the battery in step ⑤.

Ⅲ. Cycle life test of lipo rechargeable battery

The cycle life test is mainly to test the charge and discharge times of the lipo rechargeable battery when the usable capacity drops to the allowable value. Specific steps are as follows:

① The lipo rechargeable battery is discharged to the specified termination voltage (usually 3.0V) with a constant current of 0.2C at an ambient temperature of (20±5) °C. Then it is charged with a constant current of 0.2C to the termination voltage (usually 4.2V), and finally transferred to constant voltage charging (the termination current of charging is generally 0.02C).

② The lipo rechargeable battery should be discharged to the specified discharge termination voltage with a constant current of 0.2C at an ambient temperature of (20±5) °C.

③ The lipo rechargeable battery should be cycled at an ambient temperature of (20±5) ℃, and the battery should not be left for more than 1h between charging and discharging or discharging and charging.

④ The lipo rechargeable battery should be discharged and charged according to steps ① and ② until the discharge capacity is lower than 70% of the rated capacity.