A 4200 mAh pack sounds large until you count the radio. Most “battery problems” reported by installers are really specification problems: the wrong capacity for the traffic of that door.
The three consumers
Standby draw of the module (constant), wake events (fingerprint, face, card), and the Wi-Fi link when the app is used. A door opened 8 times a day behaves nothing like a shopfront opened 200 times.
Realistic expectations
For a residential door with a 4200 mAh pack, 8–12 months is a fair expectation when video is not streamed continuously. A shopfront with heavy traffic and frequent remote unlocks should be planned for quarterly checks.
Design details that matter
Low-voltage warning should start early, not at the last 5 %. Emergency USB-C input outside the door is not a luxury — it is the difference between a service call and a locksmith at midnight.
Takeaway
Ask for the standby current and the wake-event consumption in milliamps, then multiply by the real traffic of the door.