IVGM5-8K LP2G1 hybrid inverters (warning code list, flashing fault LED)
Felicity 21 error code
BMS communication alarm: abnormal communication between battery and inverter in non-SOC mode.
Likely causes
- BMS communication cable loose or damaged
- Wrong protocol selected in the inverter
- Battery DIP address or master/slave setting wrong
- Battery BMS powered down
Checks to run, in order
- 1Check the battery and inverter communication wiring
- 2Confirm the inverter's battery protocol matches the BMS
- 3Check the battery DIP switches and address
- 4Confirm the battery is powered on
Fixes
- Reseat or replace the communication cable
- Select the correct protocol and restart
- Correct the DIP address and wake the battery
When to escalate
If the alarm persists with a known-good cable and the correct protocol, escalate to the distributor with the battery model.
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 21 mean?
BMS communication alarm: abnormal communication between battery and inverter in non-SOC mode.
How do I fix Felicity 21?
Reseat or replace the communication cable Select the correct protocol and restart Correct the DIP address and wake the battery
When should I escalate Felicity 21?
If the alarm persists with a known-good cable and the correct protocol, escalate to the distributor with the battery model.
Can I reset Felicity 21 myself?
Only after isolating the AC and DC sides and running the checks above. If Felicity 21 returns immediately, stop resetting it and escalate; a repeating fault usually points to a real circuit, battery or hardware problem.
Which models show Felicity 21?
Felicity 21 is documented for IVGM5-8K LP2G1 hybrid inverters (warning code list, flashing fault LED). 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 22Battery under-voltage alarm or battery SOC low alarm: battery voltage is too low, or the BMS reports SOC too low, and the battery should be charged.
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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