The short answer
EC111 is normal right after start; if it stays, check inverter comms or re-save the configuration.
Plain explanation
From the BYD manual for the Battery-Box Premium HVS/HVM: Count LED flashes: white then blue to read the code. EC111 is normal right after start. The rest of the checklist is below; work through it in order. Installer only: DC and AC work on a live PV system is dangerous, so owners should note the code and call their installer.
Steps from the source
- Count LED flashes: white then blue to read the code
- EC111 is normal right after start
- If it stays: check inverter comm or re-save the configuration
- EC112: follow the no-charge checklist (§2.4)
Source
BYD Battery-Box Premium HVS/HVM Service Guideline & Checklist (BCU2.0) V1.1, 2025-08-08, §2.9 p10-12www.bydbatterybox.com ↗
Where installers ask this
- Fronius Gen24 + BYD: battery no longer charging? (r/fronius)
- reddit.com/r/DeutschePhotovoltaik/comments/1vjn81v/
- reddit.com/r/fronius/comments/1i11q4t/
General guidance based on the manufacturer's manual or the named source. Always follow the current manual for your exact model and your national code. DC and AC electrical work is for qualified installers only. Not affiliated with or endorsed by any brand named; trademarks belong to their owners.