FLA48200/FLA48300/FLA48500 and LUX-Y low-voltage LiFePO4 batteries (BMS fault code list)
Felicity C03 error code
Cell over-voltage: an individual cell exceeded its upper voltage limit.
Likely causes
- Cell imbalance letting one cell run ahead during charge
- Charge voltage too high for the pack
- BMS cell-voltage sensing fault
Checks to run, in order
- 1Read individual cell voltages in the battery app
- 2Compare the charge voltage with the battery datasheet
- 3Observe whether the same cell is always the highest
Fixes
- Stop charging and allow the BMS to balance the pack
- Correct the charge voltage
- Restart the unit; if the error persists, contact the repair centre
When to escalate
If one cell repeatedly hits the limit while the pack voltage is normal, escalate for cell balancing or module replacement.
Fix it with the right tools
Check the system around the fault before replacing parts: load, battery bank, PV string and commissioning settings. If you need a second opinion, send the code and your inverter model to our team.
Before you open the inverter
- Isolate both the AC and DC sides, then confirm the display is dead before touching terminals.
- Use insulated tools and one hand where possible. DC arcs do not self-extinguish like AC.
- If you see burnt terminals, swollen cells, leaking electrolyte or a burning smell, stop and escalate instead of resetting the fault.
Questions installers ask
What does Felicity C03 mean?
Cell over-voltage: an individual cell exceeded its upper voltage limit.
How do I fix Felicity C03?
Stop charging and allow the BMS to balance the pack Correct the charge voltage Restart the unit; if the error persists, contact the repair centre
When should I escalate Felicity C03?
If one cell repeatedly hits the limit while the pack voltage is normal, escalate for cell balancing or module replacement.
Can I reset Felicity C03 myself?
Only after isolating the AC and DC sides and running the checks above. If Felicity C03 returns immediately, stop resetting it and escalate; a repeating fault usually points to a real circuit, battery or hardware problem.
Which models show Felicity C03?
Felicity C03 is documented for FLA48200/FLA48300/FLA48500 and LUX-Y low-voltage LiFePO4 batteries (BMS fault code list). Confirm the code on your own unit's display or manual before ordering parts.
More Felicity error codes
- Felicity 04Low cell voltage / over-discharge protection.
- Felicity 05PV over-current fault: the PV input current exceeded the inverter's PV input limit.
- Felicity 18PV short-circuit fault on the PV input; in the warning list the same number means battery under-voltage alarm.
- Felicity 19Battery open-circuit alarm: the inverter no longer detects a battery on its terminals.
- Felicity 20Battery SOC low alarm: the battery's state of charge has fallen to the low-SOC warning threshold.
- Felicity 21BMS communication alarm: abnormal communication between battery and inverter in non-SOC mode.
Guidance reviewed 17 October 2026 by the Mishka Energy installer team. Error codes vary by brand, model family and firmware; confirm against the manufacturer manual.
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