This is the complete fault table for the Felicity FLS48100SG2 Battery — all 21 codes from the official manual on one page. On this Felicity device, a fault code means the unit has entered protection and stopped normal operation; a warning leaves it running. The exact indication (LED pattern or display code) is listed per code below.
Last checked against the official manuals on July 10, 2026.
Battery overvoltage. Total pack voltage exceeded the rated upper protection threshold during charging.
CauseTotal battery pack voltage above rated value. Charging continued past the over-voltage protection point.
Recommended fixRestart the unit. if the error persists, return to repair centre..
Source:Benutzerhandbuch - Felicity FLS48100SG2.pdf
Battery undervoltage. Total pack voltage fell below the rated lower protection threshold during discharging.
CauseOver-discharge protection triggered when total voltage or any cell fell below rated range.
Recommended fixRestart the unit. if the error persists, return to repair centre. Recharge within 18 hours after over-discharge protection.
Source:Benutzerhandbuch - Felicity FLS48100SG2.pdf
Cell overvoltage. Voltage of a single cell exceeded the rated upper protection threshold.
CauseSingle cell voltage reached protection value during charging.
Recommended fixRestart the unit. if the error persists, return to repair centre.
Source:Benutzerhandbuch - Felicity FLS48100SG2.pdf
Cell undervoltage. Voltage of a single cell fell below the rated lower protection threshold.
CauseCell voltage below protection value during discharge.
Recommended fixRestart the unit. if the error persists, return to repair centre.
Source:Benutzerhandbuch - Felicity FLS48100SG2.pdf
Charge overcurrent. Charging current reached the trigger value for 15 seconds; charging overcurrent protection activated and the battery entered fault mode disabling both charge input and discharge output.
CauseCharging current exceeded trigger value for 15 s. Inverter charge current setting may be too high.
Recommended fixFault auto-clears after 1 minute. After 10 occurrences, manual restart is required. Restart the unit; if the error persists, return to repair centre. Set inverter charge current to recommended value (60A x N, max 400A).
Source:Benutzerhandbuch - Felicity FLS48100SG2.pdf
Discharge overcurrent. Discharging current reached the trigger value for 15 seconds; discharging overcurrent protection activated and the battery entered fault mode disabling both charge input and discharge output.
CauseDischarging current exceeded trigger value for 15 s. Load or inverter discharge current may be too high.
Recommended fixFault auto-clears after 1 minute. After 10 occurrences, manual restart is required. Restart the unit; if the error persists, return to repair centre. Reduce inverter discharge current to recommended value.
Source:Benutzerhandbuch - Felicity FLS48100SG2.pdf
MOS (MOSFET) overtemperature. Internal MOSFET temperature exceeded the upper limit.
Cause1. The inner temperature is over the limitation. 2. Ambient temperature may be too high.
Recommended fixCheck whether the ambient temperature is too high. Improve ventilation; allow the unit to cool before restarting. Operating range: -20 deg C to +55 deg C.
Source:Benutzerhandbuch - Felicity FLS48100SG2.pdf
MOS (MOSFET) undertemperature. Internal MOSFET temperature is below the lower limit.
Cause1. The internal temperature is lower than the limit range. 2. Ambient temperature may be too low.
Recommended fixCheck whether the ambient temperature is too low. Move the battery indoors or warm the environment before restarting. Charging range: 0 deg C to +55 deg C.
Source:Benutzerhandbuch - Felicity FLS48100SG2.pdf
Cell overtemperature. Temperature of a battery cell exceeded the upper protection limit.
CauseCell temperature above limit. Possibly excessive ambient temperature, high current, or impaired ventilation.
Recommended fixRestart the unit. if the error persists, return to repair centre. Verify ambient temperature and ventilation.
Source:Benutzerhandbuch - Felicity FLS48100SG2.pdf
Cell undertemperature. Temperature of a battery cell is below the lower protection limit.
CauseCell temperature below limit. Possibly insufficient ambient temperature.
Recommended fixRestart the unit. if the error persists, return to repair centre. Charge in an environment within the operating temperature range.
Source:Benutzerhandbuch - Felicity FLS48100SG2.pdf
Abnormal current sampling. The BMS current measurement returned an out-of-range or invalid reading.
CauseInternal current sensor or sampling circuit reported abnormal values.
Recommended fixRestart the unit. if the error persists, return to repair centre.
Source:Benutzerhandbuch - Felicity FLS48100SG2.pdf
Abnormal output impedance. The output-side impedance measurement is outside the normal range, suggesting a wiring, contact, or load anomaly.
CauseOutput impedance abnormal. Possible loose connection, oxidised terminal, or unusual load.
Recommended fixRestart the unit. if the error persists, return to repair centre. Inspect output cabling and terminations.
Source:Benutzerhandbuch - Felicity FLS48100SG2.pdf
Parallel failed. The battery could not establish a valid parallel configuration with other units.
CauseParallel-installation error: single unit reporting parallel state, mis-wired parallel cabling, or incorrect DIP-switch IDs.
Recommended fix1. Check whether a single unit was incorrectly installed in a parallel system. 2. if the error happens during parallel installation, check wire connections; if connected correctly, finish parallel installation first then restart. 3. if the problem remains, contact your installer. Verify DIP-switch addresses per the DIP code table.
Source:Benutzerhandbuch - Felicity FLS48100SG2.pdf
Output loss. No output detected at the battery terminals.
CauseCircuit breaker open, blown fuse, or internal output failure (Sicherung durchgebrannt, Trennschalter offen oder interner Ausgangsfehler).
Recommended fix1. Check whether the circuit breaker is closed. 2. Check whether the fuse is normal (the external fuse can be replaced if blown). 3. Restart the unit; if the error persists, return to repair centre.
Source:Benutzerhandbuch - Felicity FLS48100SG2.pdf
Unable to communicate with the inverter. Maintenance troubleshooting item (no LCD code).
CauseThe wrong communication cable was used, or the battery DIP-switch settings are incorrect (Falsches Kommunikationskabel verwendet oder DIP-Schalter falsch eingestellt).
Recommended fixBefore connecting the battery to the inverter, set the battery DIP switches correctly according to the DIP-switch table. After setting the DIP switches, restart the battery to activate the DIP, then use the correct communication cable to connect the battery and the inverter.
Source:Benutzerhandbuch - Felicity FLS48100SG2.pdf· page 27
Battery does not fully charge. Maintenance troubleshooting item (no LCD code).
CauseThe charging voltage set on the inverter is too low (Ladespannung am Wechselrichter zu niedrig).
Recommended fixSet the charging voltage on the inverter according to the recommended value in the battery manual (Max. charging voltage 57.6V; Float 57.6V; Cut-off 48V).
Source:Benutzerhandbuch - Felicity FLS48100SG2.pdf· page 27
Inaccurate SOC display. Maintenance troubleshooting item (no LCD code).
CauseThe battery's SOC has not been calibrated.
Recommended fixThe SOC will automatically calibrate after one full charge cycle. First, discharge the battery to 0%, then charge it to 100%. Fully charge the battery at least once per month for accurate SOC.
Source:Benutzerhandbuch - Felicity FLS48100SG2.pdf· page 27
High current charging and discharging causes output cutoff. Maintenance troubleshooting item (no LCD code).
CauseThe charging and discharging current set on the inverter is too high.
Recommended fixSet the charging and discharging current on the inverter according to the recommended values in the battery manual (60A x N, max 400A).
Source:Benutzerhandbuch - Felicity FLS48100SG2.pdf· page 27
Battery output is interrupted due to high current during charging and discharging. Maintenance troubleshooting item (no LCD code).
CauseThe charging and discharging current settings on the inverter are too high.
Recommended fixSet the charging and discharging current on the inverter according to the recommendations in the battery manual.
Source:Benutzerhandbuch - Felicity FLS48100SG2.pdf· page 27
When multiple batteries are connected in parallel, battery data on the inverter is missing or incorrect. Maintenance troubleshooting item (no LCD code).
CauseThe parallel connection of the batteries is not set up correctly.
Recommended fix1. Check the communication cables between the batteries. 2. Check whether the battery DIP switches are set in the correct sequence (per the DIP code table).
Source:Benutzerhandbuch - Felicity FLS48100SG2.pdf· page 27
The battery indicates it is charging, but the SOC does not change. Maintenance troubleshooting item (no LCD code).
CauseThe ambient temperature is too low, preventing the battery from charging (Umgebungstemperatur zu niedrig, Laden blockiert).
Recommended fixCharge the battery in an indoor environment that meets the operating temperature range specified in the manual (charging range 0 deg C to +55 deg C).
Source:Benutzerhandbuch - Felicity FLS48100SG2.pdf· page 27
Send us the code on your screen and a Felicity technician will reply with the exact steps for your unit. Support is free for life — a first diagnosis never needs a callout.
Compiled from official Felicity user manuals. Always consult your device manual and a qualified technician before performing repairs.