The residual capacity loss of the battery, also known as the charge retention, is also known as the self-discharge rate.
When the battery is in the open circuit state, due to the internal spontaneous reaction, it will cause a certain loss of chemical energy, that is, self-discharge, resulting in a residual capacity loss of the battery.
For a specific battery, the battery charge retention is mainly affected by the battery cell manufacturing process, material system and storage conditions, etc. This requires testing the charge retention of the battery at different temperatures.
The charge retention test of battery cells can be carried out with reference to the procedures in the following table.
|
NO. |
Test steps |
Remarks |
|
01 |
Step 1: At ambient temperature, discharge the battery cells at a rate of 1C to the cut-off voltage specified by the battery cell manufacturer. |
A battery charge discharge system is required. |
|
02 |
Step 2: Let the battery cells stand for a certain period of time, it is recommended not to be less than 12 hours in a low temperature environment, and not less than 6 hours in a normal temperature and above environment. |
- |
|
03 |
Step 3: Charge the cells with a constant current of 1C to the cut-off voltage, and then charge it with a constant voltage until the current drops to a rate of 0.05C. |
|
|
04 |
Step 4: At a specific temperature, the battery cells are stored for a certain period of time, such as 30 days. And test the open circuit voltage and AC internal resistance of the battery every two days. |
A battery OCV/IR tester is required. |
|
05 |
Step 5: At a specific temperature, the battery cells are discharged at a rate of 1C to the cut-off voltage specified by the battery cell manufacturer, and the charge retention capacity C1 is recorded. |
- |
|
06 |
Step 6: At a specific temperature, the battery cells are charged at a rate of 1C to the cut-off voltage specified by the battery cell manufacturer, and then continue to charge in constant voltage mode until the current drops to 0.05C and then stop. |
- |
|
07 |
Step 7: At ambient temperature, let the battery cells stand for a specific time, it is recommended not to be less than 6h. |
- |
|
08 |
At ambient temperature, discharge the battery cells at a rate of 1C to the cut-off voltage specified by the battery cell manufacturer and then stop. The charge retention capacity C2 is recorded. |
- |
From the above brief test procedure, it can be seen that in order to test the residual capacity loss of battery cells, the indispensable battery testing equipment is a battery charge discharge system and a battery climate chamber.
WinAck Group can provide complete battery cell testing solutions. Come by, contact us for a solution that can help you succeed. For better batteries, Win & Ack!
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