The short answer
It needs inverter comms and takes about 20 min; if it doesn't finish, rerun it and do the defined restart order.
Plain explanation
From the BYD manual for the Battery-Box Premium HVS/HVM: Use latest app and firmware. BMS update needs inverter communication and takes about 20 min. 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
- Use latest app and firmware
- BMS update needs inverter communication and takes about 20 min
- If not done, run the update again
- Restart: inverter off first, then battery; wait 30 s; battery on, then inverter
- Wait 20 min
Source
BYD Battery-Box Premium HVS/HVM Service Guideline & Checklist (BCU2.0) V1.1, 2025-08-08, §2.3, p5www.bydbatterybox.com ↗
Where installers ask this
- Batterie ungenutzt (BYD Be Connect) (r/DeutschePhotovoltaik)
- reddit.com/r/DeutschePhotovoltaik/comments/1wq5in6/
- reddit.com/r/DeutschePhotovoltaik/comments/1vjn81v/
- reddit.com/r/DeutschePhotovoltaik/comments/1mxjxdd/
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.