FLA48200/FLA48300/FLA48500 and LUX-Y low-voltage LiFePO4 batteries (BMS fault code list)
Felicity C12 error code
Abnormal output impedance: the BMS measured an unexpected output impedance.
Likely causes
- Loose or corroded battery output terminal
- Damaged output cable or breaker
- Internal BMS or fuse fault
Checks to run, in order
- 1Check the battery output terminals for tightness and corrosion
- 2Inspect the output cable and breaker
- 3Restart the unit and see whether the code clears
Fixes
- Clean and retighten the output terminals
- Replace damaged cable or breaker
- Restart; if the error persists, contact the repair centre
When to escalate
If C12 returns with sound output wiring, escalate for BMS service.
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 C12 mean?
Abnormal output impedance: the BMS measured an unexpected output impedance.
How do I fix Felicity C12?
Clean and retighten the output terminals Replace damaged cable or breaker Restart; if the error persists, contact the repair centre
When should I escalate Felicity C12?
If C12 returns with sound output wiring, escalate for BMS service.
Can I reset Felicity C12 myself?
Only after isolating the AC and DC sides and running the checks above. If Felicity C12 returns immediately, stop resetting it and escalate; a repeating fault usually points to a real circuit, battery or hardware problem.
Which models show Felicity C12?
Felicity C12 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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