Checking Charge State Of A Lithium-Ion Battery Using A Battery Tester
Information
Charging a 12 V lithium-ion battery that has become totally discharged:
When a lithium-ion battery reaches an open-circuit voltage < 12.5 V or a charge state < 15%, a protection relay in the battery opens.
To recharge a lithium-ion battery that has become totally discharged, apply a voltage of 11 V - 14.4 V to the external power connection in the vehicle (at the battery terminals if the battery is removed) for at least 30 seconds using a backup battery or connect a charger in backup mode. The protection relay closes (short clicking sound can be heard in the lithium-ion battery).
The lithium-ion battery must then be charged fully with 14.4 V.
- Check the battery charge state according to the operating instructions for the relevant quick-start battery charger.
Evaluating the test results and subsequent procedure:
| Open-circuit voltage in volts | Charge state in % | Evaluation and procedure |
|---|---|---|
| 13.7 - 13.4 | 100 - 80 | Charge state OK |
| 13.4 - 13.25 | 80 - 50 | Charge state reduced; recharge battery. |
| 13.25 - 12.5 | 50 - 15 | Battery discharged; recharge battery. |
| < 12.4 | < 15 | Battery totally discharged; it might be possible to recharge it. Close protection relay, recharge battery. If the protection relay does not close, replace the battery |
> 270619 REMOVING AND INSTALLING VEHICLE ELECTRICAL SYSTEM BATTERY