BMS Lost on a Fox ESS H1 G2 single-phase hybrid inverter: The communication between BMS and Inverter is interrupted
Short answer
On a Fox ESS battery, BMS Lost means: The communication between BMS and Inverter is interrupted. The battery keeps running with some functions stopped.
Reviewed 24 September 2026 · 1 source
What it means
The manual says: The communication between BMS and Inverter is interrupted.
Part involved: battery BMS communication (CAN).
When it shows: No CAN communication from BMS.
Likely causes:
- BMS communication cable loose/faulty, battery switched off or asleep.
Is it safe?
| Does the battery stop? | Partly |
|---|---|
| Severity | Warning |
The battery keeps running with some functions stopped.
Resetting itself: yes.
Manual reset: Check BMS communication cable.
What you can check
- Read the full code and message on the inverter screen or in the FoxCloud app and note the date/time for your installer.
- Check the inverter's AC isolator next to the inverter and the solar/battery breaker in the consumer unit are ON (do not reset a breaker that trips again - call your installer).
- Check that the battery's own power switch/indicator shows it is on (only the external switch/LED the manual shows users; do not open covers).
What the engineer will check
- Check BMS CAN cable, terminations, battery DIP switches and BMS firmware; power-cycle battery per Fox procedure.
Who to ask for: Battery/hybrid installer trained on the specific battery (manufacturer-approved installer).
Certification: Battery and hybrid-inverter DC work: installer trained/approved by the manufacturer; electrical work under BS 7671 by a competent person.
What you might notice
Sources
- H1(G2)/AC1(G2) Series User Manual ↗ · V1.0.8 · page 50 · Reviewed 24 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 24 September 2026