EG4 › Problems
EG4 inverter won't communicate with or use the battery
The inverter shows a battery communication error, can't see or use the battery, or shows W027 Battery open. This page covers what the lights and codes mean, what to check first, and the causes behind it.
What the lights mean
| What you see | What it means |
|---|---|
| Yellow fault light on a 12000XP that isn't communicating with its battery, with the wiring correct | Seen when a third-party battery's management board was sending a CAN protocol the inverter doesn't recognise, left on its default instead of Lux Power. |
| 280Ah WallMount showing 100% with RUN blinking while still listed as charging | Seen on 280Ah batteries in a bank mixed with 314Ah batteries, before the battery communication chain was fixed. |
| Battery's normal light flashing during an over-the-air firmware update | The update is in progress. It is not a fault. The inverter can take 5 to 10 minutes to finish after the progress bar reads 100%. |
| LifePower4 second green light blinking while the automatic updater runs | The updater is writing firmware. A normal update takes about 60 seconds, and a recovery after a failed update about 2 minutes. |
| All lights on a LifePower4 solid after an update was interrupted | The update failed because power or the comm cable was lost during it. Running the automatic updater again recovered it. |
| Fault light on the Battery Firmware Adapter | An RS485 firmware update from the adapter did not complete. |
| Success light on the Battery Firmware Adapter | The adapter reports the update completed. The battery's displayed BMS version has still been seen unchanged afterwards. |
Error codes that go with this problem
| Code | What it means |
|---|---|
| W000 or Warning 00 | Communication failure with the battery: the inverter is not getting CAN or RS485 data from it. |
| Bat com failure or battery communication error on an 18kPV | The inverter fails to communicate with the battery. |
| Error 61 on a 6000EX or 6500EX-48 | The inverter has lost, or never set up, communication with the battery bank's management system. |
| Error 20, often together with Error 4 | Error 20 is a communication problem between a LifePower4 and the inverter. Error 4 is battery low voltage. Both appear when the battery comm cable is unplugged. |
| Error 19 on a 3000EHV | Loss of battery communication: the inverter can't talk to the battery over RS485 in closed-loop (LI 2, Pylon) mode. |
| W027: Battery open fault on a FlexBOSS21 | The inverter has disconnected from the battery and doesn't recover on its own. Grid power still reaches the loads and PV still produces. |
What to check first
- Write down the code on the inverter screen or in the app, and whether grid power and solar still work while the battery neither charges nor discharges.
- Check that the battery comm cable is fully plugged in at the battery and at the inverter, and that it is in the CAN port, not the RS485 port.
- If a battery firmware update is running over the air, wait. A flashing normal light during it is not a fault, and the inverter can take 5 to 10 minutes to finish after the progress bar reads 100%.
- If a LifePower4 shows all its lights solid after an update was interrupted by lost power or a pulled comm cable, run the automatic updater again.
- If a FlexBOSS21 shows W027 Battery open and it doesn't clear on its own, contact EG4 support with the inverter's serial number.
The causes and the fixes
Partners see the causes behind this problem, most common first, the checks that tell them apart, and the fix for each, with part numbers and recent prices when a part is involved.