Quick Answer
Evaluating battery capacity when buying used EV modules involves inspecting the battery management system, monitoring cell voltage, and performing a capacity test.
Inspecting Battery Management System (BMS)
When buying used EV modules, inspect the battery management system (BMS) to ensure it is functioning properly. Check for any error codes or alarms on the dashboard. A faulty BMS can lead to battery degradation or even a complete loss of capacity. If the BMS is damaged or missing, it may be necessary to replace it.
Capacity Testing
Perform a capacity test to evaluate the actual usable capacity of the battery. Use a device like a battery analyzer to discharge the battery to 10% state of charge and then charge it back to 100% state of charge. Measure the initial and final capacities to determine the degradation. Compare the results to the manufacturer’s specifications. For example, a 60kWh battery with a 20% degradation would have an actual capacity of 48kWh.
Cell Voltage Monitoring
Monitor the cell voltage to assess the overall health of the battery. Use a multimeter to measure the voltage of each cell. Compare the results to the manufacturer’s specifications. A voltage deviation of more than 1V from the normal range can indicate a problem with the cell. Also, measure the internal resistance of the cells to identify any signs of degradation. For example, a high internal resistance can indicate a sulfated or damaged cell.
Find more answers
Browse the full Q&A library by topic, or jump back to the topic this question belongs to.