SwitchBot Bluetooth: expose main battery status / power alarm for Lock Ultra (and Lock 2)

[Jody1818]

Integration name

SwitchBot Bluetooth

Link to integration documentation on our website

https://www.home-assistant.io/integrations/switchbot

Describe the enhancement

The SwitchBot Lock Ultra has a removable rechargeable main battery and a built-in CR123A backup battery. When the main battery is removed for charging, the lock keeps running on the backup battery.

Today: the integration exposes only a single "Battery" sensor. While the main battery is out, this sensor reports the backup battery level instead (in my case it jumped from 38% to 100%). There is no way in Home Assistant to know whether the reading comes from the main or the backup battery.

Requested: expose the "battery_status" field that PySwitchbot already parses for this lock (process_lock2 in switchbot/adv_parsers/lock.py: battery_status = mfr_data[11] & 0b00000111), for example as a binary_sensor "Running on backup battery" / "Main battery installed".

Observed data (Lock Ultra, HA 2026.9.4, PySwitchbot 2.4.1):

Situation	Battery sensor	mfr_data[11]	battery_status	power_alarm
Main battery removed (running on backup)	100	0x02	2	false
Main battery installed	63	0x00	0	false

Raw manufacturer data:

• Main battery removed: b0 e9 fe e1 91 0a 37 81 00 64 00 02
• Main battery installed: b0 e9 fe e1 91 0a 38 81 00 3f 00 00

Use cases

I have an automation that notifies me and adds a to-do item when the lock battery drops to 20%, 15%, 10% and 5%, and removes the to-do item when the battery is above 30%.

While the main battery is out for charging, the Battery sensor shows the backup battery level (100%), so Home Assistant thinks the lock is fully charged. With a "Running on backup battery" entity I could:

• Remind myself to put the main battery back in the lock if it stays out too long.
• Ignore the misleading backup battery reading in battery automations and dashboards.

Anything else?

• PySwitchbot lock parser: https://github.com/sblibs/pySwitchbot/blob/master/switchbot/adv_parsers/lock.py
• SwitchBot Lock Ultra product page (main + backup battery): https://us.switch-bot.com/products/switchbot-lock-ultra
• The values above come from one test in each state (taken from the integration diagnostics). Happy to provide more diagnostics if needed.

[github-actions[bot]]

🏷️ I've automatically added the integration: switchbot label to help categorize this feature request.