It is quite possible for the Nest Doorbell's battery to be low (possibly even critically low), even when the device is connected to a transformer. This is because, by design, the Nest Doorbell trickle-charges its battery extremely slowly. Therefore, any factors that increase energy usage or decrease battery charge rate can result in a net discharge over time, even when the doorbell is wired, for example:
- Cold weather
- Many events in the camera's field of view
- An underpowered transformer
Unlike the Google Home app, HomeKit will warn you if a camera's battery is low, even when that camera is plugged in.
Using Starling Home Hub with your doorbell will not increase its battery usage.