If you have a Nest Thermostat, you may be wondering if it has a battery, and if you need to keep that battery charged.

The Nest Thermostat does have a battery, but you generally don’t need to charge it. The thermostat gets its power from the lines that come from your heat pump or furnace. Usually, the standard thermostat wires provide a 24-volt output that goes into the thermostat, keeping it running.

I’ve had a Nest Thermostat for over five years, and I’ve never once charged the battery.

Why Does the Thermostat Have Batteries?

If you almost never need to charge the Nest Thermostat’s battery, why does it have one?

The Nest thermostat has a battery so it can keep operating during power outages. There is a small lithium-ion battery in the Nest Learning Thermostat, and the standard Nest Thermostat has AAA batteries for the same reason.

This way, the thermostat will continue to operate and store your settings even if the lights go out for a few days. If there is a power outage, a notification will pop up on the thermostat itself telling you that it does not have power coming in.

So, you don’t need to charge the battery routinely – it will power itself from the thermostat power. But you do have a battery backup in the event of a power outage to keep your settings and keep everything running in the thermostat.

How to Charge the Nest Thermostat

If there’s a long outage, the battery in your Nest Thermostat may run down. If that’s the case, you’ll want to recharge it.

For the standard Nest Thermostat, simply pop the thermostat off the wall, open the back, and insert new AAA batteries from a known manufacturer.

For the Nest Learning Thermostat, take the thermostat off the wall, plug in a USB cable, and plug the cable into a phone charger. It will take about 2 hours for the thermostat’s battery to recharge fully.

Pop quiz: does the Nest Thermostat have a camera? I explored this question in detail–here’s the answer.