Driving range is the main performance indicator of an EV, and this is mainly determined by the available capacity of the EV battery system.
Lithium-ion batteries are highly sensitive to temperature and current rate. By analyzing the charge-discharge curve of the battery under different working conditions, and analyzing its charge-discharge capacity and energy and other parameters, the battery's suitable operating temperature range and its tolerance to temperature changes can be analyzed.
Similar to the charging test, the following table shows the specific test steps for discharge performance test of battery cells at different temperatures and different current rates. The battery test equipment required to do these tests is an EV battery tester and a Thermal Test Chamber.
|
NO. |
Test steps |
Remarks |
|
01 |
Step 1: Place the cells in a constant temperature climate chamber at 25°C for 6 hours. |
Make sure that the cell temperature is the same as the ambient temperature. |
|
02 |
Step 2: Discharge the cells with a constant current of 1C rate to the termination voltage. |
- |
|
03 |
Step 3: Place the cells in a constant temperature climate chamber at 25°C for 2 hours. |
|
|
04 |
Step 4: Charge the cells with a constant current of 0.33C to the cut-off voltage, and then charge it with a constant voltage until the current drops to a rate of 0.05C, and then let it stand for 2 hours. |
- |
|
05 |
Step 5: Place the cells in a constant temperature climate chamber at -20°C for 12 hours. |
- |
|
06 |
Step 6: Discharge the cells with a constant current of 0.33C rate to the termination voltage. |
- |
|
07 |
Step 7: Repeat steps 3 to 6 three times, the discharge current rate in step 6 is changed to 1C, 2C and XC respectively. |
The XC is the maximum discharge rate of the battery cell specified by the battery cell manufacturer. |
|
08 |
Step 8: Repeat steps 3 to 7 three times, where the temperature of step 5 is modified to 0 °C, 25 °C, and 55 °C, respectively. |
The three temperature points represent low temperature, normal temperature and high temperature respectively, which can be adjusted according to the working conditions. |
For different battery cells, as the temperature rises, the change trend of the discharge capacity is different.
In order to more comprehensively analyze the charge-discharge performance of EV batteries at different rates, more complex simulation tests can be used to analyze battery cycles under EV starting, braking, and acceleration conditions.
WinAck Group can provide complete EV battery testing solutions. Come by, contact us for a solution that can help you succeed. For better batteries, Win & Ack!
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