The symptoms of electric bicycle battery failure can vary and usually appear when the battery condition is poor or there is a problem with the charging system. The main failure symptoms are as follows:

1. Battery does not charge
   Even when connected to the charger, charging does not start, or the charging indicator does not blink or light up at all.
   This may be due to a problem with the charger, poor contact between the charger and battery, or an issue with the battery itself.

2. Sudden power off while riding
   The battery may be discharged or the voltage may drop, causing the power to cut off suddenly. The battery may be completely discharged.
   The battery's over-discharge protection circuit may have activated.

3. Rapidly shortened battery life
   If the riding distance after a full charge is significantly reduced, the battery life may have ended and the performance degraded.
   Battery cell performance may have declined or cell imbalance may have occurred.

4. Battery overheating
   If the battery feels abnormally hot during charging or use, it indicates overheating and potential internal cell or circuit problems.
   Overheating shortens battery life and may cause fire hazards.

5. Strange smell or smoke from the battery
   If you notice a burning smell or smoke, it is a sign of battery damage or internal short circuit. Immediate cessation of use and expert inspection is critical.

6. Unstable battery voltage
   If battery voltage drops suddenly or is unstable, it could be due to cell imbalance or Battery Management System (BMS) errors.
   Faulty BMS or defective cells cause abnormal voltage drops.

7. Capacity shortage even after charging
   Even after fully charging the battery, the capacity remains insufficient or does not function properly.