How to reset a lithium battery

The most common cause is usually not a faulty battery cell, but rather an external power supply or connection problem—a faulty charger, a blown fuse, or poor plug contact causes the BMS to enter a protection state.

The following troubleshooting steps are arranged from the easiest to the most difficult (each step: phenomenon → possible cause → solution → precautions) – also suitable for car owners searching for the keyword “how to reset lithium battery”.

1) Check the charger and power supply.

• Symptom: The charger indicator light is off, it cannot charge or has no response at all.
• Possible causes: No power in the socket, broken extension cord, damaged charger power cord, or malfunction of the charger itself.
• Solutions: Try a different power outlet; try a different power cord or a spare charger; use a multimeter to check if there is voltage at the charger’s output.
• Precautions: Disconnect the power supply before operation; do not touch the metal terminals with bare hands in a humid environment; use an instrument with an appropriate range for measurement.

2) Check the fuses/circuit breakers.

• Symptoms: The instrument panel has no power, the charger is connected but there is no output, and the vehicle has no power source.
• Possible cause: The main fuse or the charging circuit fuse has blown, causing the circuit breaker to trip.
• Solution: Refer to the vehicle’s electrical diagram to locate the fuse, replace it with a fuse of the same specification, or reset the circuit breaker; confirm whether the problem is resolved after replacement.
• Precautions: Never use copper wire or metal wire as a temporary bridging material to replace the fuse; record the fuse specifications and amperage before replacement.

3) Check the contact between the charging plug, socket, and connector (poor plug contact).

• Symptoms: Unstable contact during charging, flashing charging indicator, overheating at the plug location, or intermittent operation.
• Possible causes: loose plug, oxidized/dirty pins, damaged cable, or insufficient contact pressure.
• Solution: After powering off, clean the plug and socket (with contact cleaner or alcohol), check if the pins are bent or burned, and replace the plug or wiring harness if necessary and re-secure it.
• Precautions: Cleaning and replacement should be performed with the power off; avoid extensive sanding of the contact surface; ensure insulation and waterproofing when repairing connectors.

4) Check if the charger output specifications match the battery (voltage/current mismatch).

• Symptoms: The charging display shows normal but the battery does not fully charge, or the charger malfunctions or the BMS reports an error.
• Possible causes: Incorrect charger output voltage (too low and the BMS cannot be woken up, too high and the BMS may block it), or excessive/insufficient current that is incompatible with the battery pack.
• Solution: Check the battery’s nominal voltage (e.g., 48V, 72V) against the charger’s output nominal voltage and maximum charging current; if necessary, replace it with a charger that matches the battery’s specifications.
• Precautions: Do not use a charger with a voltage higher than the battery’s nominal voltage; if you are unsure of the specifications, check the device nameplate or consult the manufacturer.

5) Low temperature protection (cannot be charged in low temperature environments)

• Symptom: The battery fails to charge in cold weather or the charger/battery indicates a temperature malfunction, and charging is interrupted.
• Possible cause: The BMS or some chargers have low-temperature protection, which will block charging at low temperatures to protect the battery cells.
• Solution: Park the battery/vehicle in a warm environment to allow the battery to warm up to the manufacturer’s recommended charging temperature range before charging; if the vehicle is to be operated at low temperatures for an extended period, consider using a system with temperature compensation or a heating kit.
• Precautions: Do not use open flames or high temperatures to rapidly heat the battery; follow the manufacturer’s recommended safe warm-up methods and temperature ranges.

6) BMS protection triggered (BMS protection)

• Symptom: The instrument panel or charger displays a fault code, and the vehicle fails to power on or stops immediately after charging.
• Possible causes: The BMS detects over-discharge, over-current, short circuit, abnormal cell voltage, or communication failure, and automatically enters protection mode.
• Solutions: First, follow the BMS reset procedure in the manufacturer’s manual (e.g., disconnect the main relay/isolating switch for a few minutes and then close it); you can try low-current slow charging wake-up (using a charger and current approved by the manufacturer); if you have a dedicated communication tool or reset button, operate according to the instructions; if it still cannot be restored, contact authorized repair services.
• Precautions: Avoid using high current to forcefully remove the protection; do not open the BMS casing at will to avoid voiding the warranty or causing danger.

7) Cell voltage imbalance or mismatch.

• Symptoms: The total voltage appears normal, but the vehicle’s range is significantly reduced; the BMS repeatedly balances or reports errors; some individual cell voltages are significantly low/high.
• Possible causes: aging or inconsistency of individual battery cells, or imbalance within a group caused by damage to a certain module.
• Solution: Use battery management/testing tools to measure the voltage of each battery cell; for slight imbalances, use a balancing charger to balance the cells in the group; for severely defective cells, replace the corresponding cell/module.
• Precautions: Individual cell testing and replacement require professional operation; randomly replacing cells with different models may cause more serious problems.

8) Software/communication issues or a need for a “soft reset” (how to reset lithium battery)

• Symptoms: BMS communication failure, vehicle displays error codes or remains abnormal after reset; conventional power off and restart is ineffective.
• Possible causes: BMS firmware stuck, communication line/CAN bus malfunction, or BMS internal state needs to be cleared.
• Solution: First, perform a complete power outage (disconnect the main power supply and wait 5–15 minutes before reconnecting) to attempt a soft reset; if the manufacturer provides specific reset procedures or tools, follow the instructions; if necessary, have the manufacturer/authorized repair technician use a dedicated diagnostic tool to read the error code and reset or upgrade the firmware.
• Precautions: Do not flash the BMS firmware without authorization; operations involving communication interfaces should be performed by technicians familiar with the system.

9) Battery capacity degradation or cell damage (battery pack replacement required)

• Phenomenon: The range drops rapidly after a full charge, the internal resistance increases, the charging time is abnormally shortened, or the battery drains quickly after being fully charged.
• Possible causes: battery aging, cycle expiration, internal short circuit, or severe degradation of individual cells.
• Solution: Conduct capacity or load tests to confirm the actual capacity; if the actual capacity is lower than the threshold required by the manufacturer/operation (e.g., <70–80% depending on the usage scenario), consider replacing the battery module or the entire battery pack.
• Precautions: Replacement must use cells/modules of the same specifications and be compatible; disposal of used lithium batteries must be carried out in accordance with environmental regulations.

When should the charger be replaced?

• If the charger has no stable output on multiple confirmed sockets and multiple batteries, and has an internal odor, overheats, or smokes;
• If the charger’s output voltage/current is significantly unstable or does not match the battery specifications, it will cause the BMS to repeatedly alarm;
• If the charger’s safety protections (such as temperature sensor, current limiting, automatic disconnect) fail or the manufacturer has stopped maintenance or firmware upgrades are not available, it should be replaced.

Three recommended standards for choosing a charger

1. Electrical matching: The output voltage and maximum charging current are strictly matched with the nominal voltage/capacity of the battery pack; supports the CC/CV charging curve of lithium batteries.
2. Safety and Communication: Equipped with overvoltage/overcurrent/short circuit/temperature protection, and preferably able to communicate with BMS (CAN/RS485, etc.) to achieve controlled charging and fault diagnosis.
3. Certification and after-sales service: Choose products with reliable certifications such as CE/UL, clearly defined IP protection levels, and warranties and technical support from manufacturers or distributors; for long-term use, attention should also be paid to heat dissipation performance and casing quality.

If the problem persists after following the above steps, it is recommended to stop disassembling complex components and contact the original manufacturer or a qualified repair shop for further diagnosis. Would you like me to provide a more detailed checklist of the specific testing methods for any of the above steps (e.g., how to use a multimeter to test the output, how to read BMS error codes)?