BYD | BCU LED Event Codes (EC) | 100–112

A continuously white LED indicates standby. A flashing white LED indicates charging or discharging. When the battery starts, the LED flashes white and blue at 0.5-second intervals, normally for about one minute during startup. If the LED flashes blue at 1-second intervals, it is displaying an event code. Start counting when the white LED begins to flash, then count the blue flashes.
Examples:
1x white, 3x blue → EC 103
1x white, 11x blue → EC 111
3x white, 3x blue → EC 303
Many faults are caused by an incorrect communication connection, incorrect app configuration or a missing restart after configuration with the app or BCP tool.

Note: If the battery has not been configured correctly in the app, the event code can be misleading.

EC 102
Abnormal shutdown/open cover, pre-charge fault or reversed DC polarity.

• Check the DC cable connection between battery, inverter and any DC busbar in between.
• Close the BCU connection-area cover correctly. For safety reasons the battery cannot be switched on while this area is open.
• Try to shut down the BCU correctly by holding the button for 5 seconds.
• If the LED goes out, check the installation and restart the system correctly: battery first, then inverter.
• If the LED remains continuously blue or continues flashing EC 102, remove the BCU from the tower to avoid deep discharge, measure the voltage and contact a service partner.

EC 103
Voltage-sensor fault / BMU-to-BMS communication fault.

• Make sure all DIP switches are in the correct position. For most configurations they are all on the left; exceptions include certain parallel configurations and Kostal PIKO MP.
• Remove the top module and check whether the event code disappears.

Note: A module with communication problems can sometimes work normally in the lowest position because no communication to the base is required there.

EC 104
Temperature-sensor fault.

• Use the BCP PC tool to review module cell data under “Diagnosis” and identify the affected module, or use the module-exclusion method.

EC 105
Pack-voltage sensor fault.

• Check the DC cable connection at the battery, inverter and any DC busbar.
• Restart the system correctly.

EC 106
Current-sensor fault.

• Make sure the latest firmware is installed and restart the battery correctly.

EC 107
Undervoltage.

• Shut the system down promptly to avoid further discharge. Check whether it can be shut down normally by holding the LED button for 5 seconds.
• If it cannot be shut down normally, lift/remove the BCU from the tower.

EC 108
Pre-charge circuit fault.

• Check the DC cable connection at the battery, inverter and any busbar in between.
• Restart the system correctly. To switch the battery off correctly, hold the button for 5 seconds. When switching on, start the battery first and then the inverter.

EC 109

• Make sure the latest firmware is installed and restart the battery correctly. If the problem remains, a module is likely to be the cause.

EC 110
Low voltage. The system must be charged very soon and should not be discharged further.

1. Shut the system down quickly to avoid further discharge. Check whether it shuts down normally by holding the LED button for 5 seconds. If not, lift/remove the BCU. Follow the service-guide procedure for voltage measurement and undervoltage.
2. Keep the battery switched off or the BCU removed while locating the cause. Check the other service-guide steps and the inverter, including firmware and defined restart procedure. Determine why maintenance charging is not taking place, for example because of an inverter or sensor fault. Do not switch the battery back on until it has been confirmed that the inverter should be able to charge it.
3. If all checks have been completed and the system still cannot charge, prevent further discharge and contact service.

EC 111
This can be normal immediately after the battery has been started. The LED should become continuously white when inverter communication is established or directly after the configuration has been completed and saved. In Be Connect, complete the entire wizard. In Be Connect Plus, save the configuration again via “Setup” and restart the tool if necessary to refresh the display. Also make sure all DIP switches are in the correct position. If EC 111 remains despite correct inverter communication and a newly saved configuration, remove the top module and check whether the event code disappears.

EC 112
No communication with the inverter.

• Check communication between the battery and inverter.