Battery communication lost during backup
Fronius · Primo GEN24
What does 904 mean?
The Fronius Primo GEN24 208-240 inverter has lost communication with the connected battery system while operating in backup power mode. This critical failure prevents the inverter from managing battery power, leading to a backup power shutdown.
Common Causes
- Battery communication lost during backup.
- Communication cable fault.
- Battery system fault.
Repair Steps & Checklist
Click steps to track your progress.
- 1
Verify all communication cables between the Fronius Primo GEN24 208-240 inverter and the battery management system (BMS) are securely connected and free from damage.
- 2
Check the battery system's status indicators and internal diagnostics for any faults related to its communication module.
- 3
Ensure the battery system remains powered on and operational, as a battery shutdown will also cause communication loss.
- 4
If the system allows, perform a controlled shutdown and restart of both the inverter and the battery system to re-establish communication.
- 5
If the fault persists, this may indicate an internal communication hardware fault in either the inverter or the battery; contact Fronius service or battery supplier.