Alarm-BMS: Battery management issue

The "Alarm-BMS" error indicates that the Battery Management System (BMS) responsible for monitoring and protecting the battery has detected an issue and has sent an alarm signal to the inverter. The BMS constantly checks the battery and needs it to function properly.

Why it’s problematic

A BMS alarm can interrupt the normal operation of the battery system, potentially affecting energy storage, charging, and discharging processes.
Ignoring BMS alarms can lead to battery damage or safety hazards, as the BMS is crucial for preventing overcharging, over-discharging, and other potentially harmful conditions.

Possible causes

Battery cell imbalance: The BMS monitors individual battery cells for voltage and temperature differences. An imbalance beyond acceptable limits can trigger an alarm.
Over-temperature or under-temperature: The BMS has temperature sensors to ensure the battery operates within a safe temperature range. Extreme temperatures can cause alarms.
Over-current or over-voltage: The BMS monitors current and voltage levels during charging and discharging. Exceeding safe limits will trigger alarms.
Communication error: A loss of communication between the BMS and the inverter can also result in a BMS Alarm.
Internal BMS fault: A malfunction within the BMS itself can trigger false alarms or prevent it from functioning properly.

Before you begin

Safety First: Working with electrical equipment always involves risks. Ensure you are qualified and follow appropriate safety precautions. Disconnect the inverter from both AC and DC sources before performing any physical inspection or adjustments.

Gather Information: Before starting troubleshooting, have the inverter manual on hand. You should also gather information about the inverter model and serial number, the installation date, and the PV array configuration (number of panels, capacity, and number of strings).

Troubleshooting steps

Check the inverter display: Note the specific BMS alarm code or message displayed on the inverter. This information will provide clues about the nature of the problem.
Consult the battery and BMS manuals: Refer to the documentation for your specific battery and BMS for detailed information on alarm codes, troubleshooting steps, and recommended actions.
Inspect battery connections: Ensure that all battery connections, including power cables and communication cables, are secure and free from damage or corrosion. A break in the power cable connection can be a cause for a BMS alarm. Loose connections or breaks can be found on the battery side or the inverter side.
Check battery temperature: If an over-temperature or under-temperature alarm is present, verify the actual battery temperature using a thermometer. Compare the reading to the manufacturer's specifications.
Monitor battery voltage and current: If over-current or over-voltage alarms are present, use a multimeter or the inverter's monitoring system to check the battery's voltage and current levels. Compare these values to the acceptable operating ranges.
Reset the BMS (if possible): Some BMS systems have a reset function that can clear temporary errors or communication glitches. Consult the BMS manual for instructions.

Verifying the solution

After addressing the identified problem, observe the inverter's display. The BMS alarm should clear, and the inverter should resume normal interaction with the battery system. This can be confirmed by checking the inverter's display and any connected monitoring systems for normal battery parameters and status indicators.

If the problem is not resolved

If the error persists after following all the above steps, there might be an internal fault within the inverter or the battery system.

As a system owner: In this case, contact the inverter installer or distributor for further assistance. You can find the details of your installer in the MyAutarco app.
As a certified installer: Contact Autarco Support, you can submit a support case via Helios.