LG RESU battery FAULT light on: what it means and what to do
When the FAULT light on the front of an LG Chem RESU battery is on, the battery is in a warning state because a condition such as voltage or temperature is outside its design limits. LG says the inverter stops operating when a warning is reported, and the warning clears on its own if the battery returns to normal. If it does not clear, the battery needs a qualified technician.
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Common causes
- Battery over voltage or under voltage.
- Battery over temperature or under temperature.
- Charge or discharge over current.
- BMS internal communication problem.
- Cell voltage imbalance.
Safe steps to try
- Read the four lights The RESU has four front lights: ON, Charging, Discharging and FAULT. Note which are lit.
- Check your inverter or app for the warning LG says to use the inverter's monitoring to see what caused the warning. Write down the message or fault ID shown on the inverter screen or app.
- Give it time to clear LG says the abnormal state clears when the battery recovers normal operation, for example after a temperature extreme passes.
- Do not open the wiring box LG's fault steps involve opening the battery wiring box and switching the breaker and auxiliary power switch, which is for a qualified installer.
When to call a professional
If the FAULT light stays on, contact your installer or LG's service contact with the fault ID or inverter log. LG's manual says to contact them or your distributor immediately if the battery or inverter shows FAULT or fails to operate. Also check whether your RESU 10H is covered by the recall.
Frequently asked questions
- Will the battery still back up my home?
- No. LG says the inverter stops operating when the battery reports a warning.
- Could this be related to the recall?
- Possibly, if you have a RESU 10H. Check the serial number against the recall and contact LG Energy Solution Michigan.