C03Fault

Felicity battery error C03

Cell overvoltage

Faultthe battery enters fault protection and stops normal operation until the fault is cleared — how it is shown (LED pattern or display code) depends on the model.

The exact meaning depends on your model:

FLA12100

BatteryFault

Also applies to:FLA48200

What it means

Cell overvoltage

Cause: An individual cell reached its over-voltage protection value during charging, typically from cell imbalance letting one cell run ahead of the pack, so the BMS stopped charging.

How to fix it

  1. Restart the unit.
  2. If the error persists, contact the repair center.

Source: Felicitysolar FLA12100 12.5Kwh Battery Energy Storage System User Manual.pdf, p.1 · Felicitysolar FLA48200 48V 200Ah 10kWh Lithium Phosphate Battery User Manual.pdf, p.12

FLA48250

BatteryCritical

What it means

Cell overvoltageIndividual cell voltage has exceeded its upper protection threshold.

Cause: An individual cell reached its over-voltage protection value during charging, typically from cell imbalance letting one cell run ahead of the pack, so the BMS stopped charging.

How to fix it

  1. Restart the unit.
  2. If the error persists, contact the repair center.

Source: 6peluqppy_66a93554057c8.pdf, p.12

FLA48250-EU

BatteryFault

What it means

C03Cell overvoltage.

Cause: An individual cell reached its over-voltage protection value during charging, typically from cell imbalance letting one cell run ahead of the pack, so the BMS stopped charging.

How to fix it

  1. Restart the unit.
  2. If the error persists, contact the repair center.

Source: FLA48250-EU_Manual.pdf, p.8

FLA48500

BatteryFault

Also applies to:HE-GF-FLA-48500

What it means

Cell overvoltageIndividual cell overvoltage protection triggered.

Cause: One or more cells exceeded the per-cell upper voltage limit.

How to fix it

  1. Restart the unit.
  2. If the error persists, contact the repair center.

Source: felicitysolar FLA48500 LiFePO4 Battery System for Households User Guide.pdf · HE-GF-FLA-48500 Manual_20250327_EN.pdf

FLS48100SG2

BatteryFault

What it means

Cell overvoltageCell overvoltage. Voltage of a single cell exceeded the rated upper protection threshold.

Cause: Single cell voltage reached protection value during charging.

How to fix it

  1. Restart the unit.
  2. If the error persists, return to repair centre.

Source: Benutzerhandbuch - Felicity FLS48100SG2.pdf

LPBF48100-M

BatteryFault

What it means

Single cell overvoltageIndividual-cell over-voltage fault displayed on the LCD BMS fault code / flag screen (section 4.4); one or more cells exceeded the upper cell-voltage limit.

Cause: Cell imbalance during charging or charger settings allowing individual cells to drift above their safe ceiling.

How to fix it

Restart the unit, if the error persists, contact the repair center.

Source: 358-010291-07.pdf, p.8

LPBF48200-H

BatteryFault

Also applies to:LPBF48100-H

What it means

Single cell overvoltageAn individual cell voltage has exceeded the protection limit.

Cause: One cell voltage above safe upper threshold (cell imbalance or overcharge).

How to fix it

Restart the unit; if the error persists, contact the repair center.

Source: Manual-LPBF48200-H.pdf, p.10

LPBF48350

BatteryFault

What it means

C03

Cause: Cell overvoltage — a single cell reached the protection value during charging, typically from cell imbalance letting one cell drift above its safe ceiling.

How to fix it

Restart the unit, if the error persists, contact the repair center.

Source: Felicitysolar LPBF48350 17.5kWh 48V Solar Battery Pack with BMS User Guide.pdf

LUX-E-48100LG03

BatteryFault

Also applies to:LUX-Y-48280LG01LUX-Y-48300LG01

What it means

Cell overvoltage

Cause: An individual cell voltage exceeded the upper protection threshold.

How to fix it

  1. Restart the unit.
  2. If the error persists, contact the repair center.

Source: LUX-E-48100LG03-Lithium-Battery-User-Guide.pdf, p.12 · LUX-Y-4828048300LG01-Lithium-Battery-User-Guide.pdf, p.8

LUX-E-48200LG03

BatteryFault

Also applies to:LUX-E-48230LG03LUX-E-48250LG03

What it means

C03

Cause: Cell overvoltage — a single cell reached the protection value during charging, typically from cell imbalance letting one cell drift above its safe ceiling.

How to fix it

  1. Restart the unit.
  2. If the error persists, contact the repair center.

Source: LUX-E-48200LG03-Lithium-Battery-User-Guide.pdf, p.12 · LUX-E-48230.250LG03-Lithium-Battery-User-Guide.pdf

LUX-X-48050LG01

BatteryFault

Also applies to:LUX-X-48050LCG01LUX-X-48050LMG01LUX-X-48050LG01M2LUX-X-48050LG01M3LUX-X-48050LG01M4

What it means

C03Cell overvoltage.

Cause: A single cell voltage reached the protection value during charging — typically cell imbalance letting one cell drift above its safe ceiling.

How to fix it

Restart the unit, if the error persists, contact the repair center.

Source: LUX-X-48050LG01-low-voltage-battery-user-guide.pdf, p.17

LUX-X-48100LG01

BatteryCritical

Also applies to:LUX-X-48100LCG01LUX-X-48100LMG01

What it means

Cell overvoltageAn individual cell voltage has exceeded its upper protection threshold.

Cause: A single cell voltage reached the protection value during charging — typically cell imbalance letting one cell drift above its safe ceiling.

How to fix it

Restart the unit; if the error persists, contact the repair center.

Source: LUX-X-48100LG01-Litium-Battery-User-Guide.pdf, p.17

LUX-X-48100LG01-US

BatteryCritical

Also applies to:LUX-X-48100LCG01-USLUX-X-48100LMG01-USLUX-X-48100LG01-USM2LUX-X-48100LG01-USM3LUX-X-48100LG01-USM4LUX-X-48100LG01-USM5LUX-X-48100LG01-USM6LUX-X-48100LG01-USM7+1

What it means

Cell overvoltageAn individual cell voltage has exceeded its upper protection threshold.

Cause: A single cell voltage reached the protection value during charging — typically cell imbalance letting one cell drift above its safe ceiling.

How to fix it

Restart the unit, if the error persists, contact the repair center.

Source: 358-S010024-03LUX-X-48100LG01-User-manual_compressed.pdf, p.23

Frequently asked questions

What does error C03 mean on a Felicity battery?
It depends on the model — 17 devices use code C03. On the FLA12100 it means: Cell overvoltage. The card for each model on this page gives its exact meaning and fix.
Is error C03 a fault or a warning?
C03 is a fault code: the battery enters protection and stops normal operation until it is cleared.
How do I clear or fix error C03?
Restart the unit. if the error persists, contact the repair center. The exact steps for each affected model are listed on this page.

Related error codes

Prefer the full written guide? Read the complete Felicity inverter error-code guide

Compiled from official Felicity user manuals. Always consult your device manual and a qualified technician before performing repairs.