The Nest Doorbell (wired, 2nd gen) has no battery to run flat: it draws power from the wires of an existing doorbell circuit through a transformer, and a power fault looks like a doorbell that does not light, restarts at random, or drops offline. The first suspects are the transformer and its connection, because a transformer that is too weak or a loose terminal gives exactly those symptoms.
A power outage can also leave the doorbell failing to reconnect, which owners fixed by cycling both the doorbell and the router. If the doorbell is connected to a power adapter, unplug it for ten seconds and plug it back in as a restart. The status light tells you what is happening: white after a restart, yellow during a reset, and no light at all for no power. Do not work on the wiring with the circuit live.
Differential
Likely causes of “Nest Doorbell (wired, 2nd gen) has power or battery problems”, and how to tell them apart
- 1
A weak or failing transformer
What separates it The doorbell restarts, loses video or does not light
How to confirm Check the transformer's rating against the doorbell's requirement and replace it if it is too low
- 2
A loose terminal connection
What separates it The doorbell works intermittently
How to confirm With power off, check both wires are tight at the doorbell terminals
- 3
A power outage
What separates it The doorbell does not reconnect afterwards
How to confirm Cycle power to the doorbell and restart the router
- 4
A tripped breaker
What separates it The doorbell and chime are both dead
How to confirm Check the breaker for that circuit
- 5
A failed doorbell
What separates it No light with good power
How to confirm Contact Google Nest support
Before you touch a setting
Record this first — changing settings destroys the evidence
- The transformer's voltage and VA rating
- Whether the chime works
- What the doorbell's light shows
- Whether the problem followed a power cut
Try in this order
0 of 6 completedRestart by cycling power
ReversibleUnplug the adapter for ten seconds or switch the breaker off and on.
Check the breaker
ReversibleMake sure the circuit is on.
Inspect the terminals
ReversibleWith power off, check the wires are tight.
Check the transformer
ReversibleCompare its rating with the doorbell's requirement.
Restart the router
ReversibleAfter a power cut, cycle the router too.
Contact Google Nest
ReversibleIf it still has no light.
Model-specific
What is true of this model and not of its siblings
- Power, not battery
- The wired model needs a suitable transformer; the battery model is a different product.
- The light
- White after a restart, yellow during a reset, no light with no power.
- What a transformer rating means
- A doorbell transformer is rated in volts and volt-amperes; an old one rated for a mechanical chime may not give the video doorbell enough steady power, which looks like random restarts. Compare its label with Google's requirement for the wired 2nd gen.
- When a chime kit helps
- A doorbell chime that is an old mechanical type can drop the voltage when it rings; a chime that suits a video doorbell, or the recommended setup in Google's guide, avoids it.
Stop boundary
When this stops being a self-service repair
- !If the transformer is correct and the doorbell has no light, contact Google Nest support
- !If you are unsure about the wiring, use an electrician
- !If the doorbell is hot or smells burnt, switch off the circuit
Evidence ledger
Sources behind this answer
Exact questions
Common questions
Does the Nest Doorbell wired 2nd gen have a battery?+
No, it runs from the doorbell wiring and a transformer.
Why does my doorbell keep restarting?+
A weak transformer or a loose terminal is the usual cause.
Why did it not reconnect after a power cut?+
Cycle power to the doorbell and the router.
Is it safe to check the wiring?+
Switch off the breaker first, and use an electrician if unsure.
Why does my doorbell restart when someone rings it?+
The chime can drop the voltage; a stronger transformer or the right chime setup fixes it.
Can I test the transformer myself?+
A multimeter reading at the doorbell terminals shows the voltage, but an electrician should do it if you are unsure.