Skip to Content

Will Nest Thermostat Work Without Power? 3 Essential Tips

Will Nest Thermostat Work Without Power

According to Fortune, the Nest thermostat is the ideal thermoregulator for anyone curious to join the smart home bandwagon.

This device has been touted as energy-efficient and capable of learning user habits to ensure their homes’ temperatures are favorable minutes before they arrive from work.

That said, can Nest offer such features during a power cut?

The Nest thermostat will work without power for a while, thanks to its built-in rechargeable battery. However, when the battery level drops below 3.6V, it switches to a power-saving mode that disables its Wi-Fi connectivity. In this mode, it loses its smart functions, such as remote control.

How the Nest Thermostat Works Without Power

Read on for more insights into how your Nest thermostat functions during a power cut, how to recharge it, ways to check its battery level, and how you can prevent its smart functionality from shutting down.

During a power outage, the built-in backup battery automatically kicks in to keep the Nest thermostat operational for some time. However, it doesn’t take long before the battery loses its charge.

But before it completely shuts down, the Nest thermostat goes into an energy-saving mode. This mode automatically disables the Wi-Fi connectivity and any real-time updates to preserve the battery charge.

In this state, it is impossible to operate the thermostat remotely. 

However, you can perform only the most essential functions by physically operating the thermostat.

How the Nest Thermostat Works

The Google Nest thermostat works by measuring your home’s temperature at different times of the day.

Through its sensors, it detects when you are away and adjusts your HVAC equipment to lower your home’s temperature, reducing energy consumption. 

Additionally, it learns your arrival and departure times and raises or lowers the temperature to ensure your home is comfortable by the time you arrive.

You can use Nest with different types of HVAC equipment, including:

  • Traditional furnaces
  • Heat pumps
  • Electric-to-hydronic conversions

How To Charge Your Nest Thermostat

In normal circumstances, your HVAC equipment charges the Nest thermostat batteries directly through the Rh and Rc wiring. 

However, the HVAC system may sometimes fail, forcing you to recharge the battery manually.

In such an instance, you will receive a low battery notification indicating the batteries need a recharge.

There are two ways you can use to charge the Nest thermostat:

Using a USB Cable

The Google Nest thermostat comes with a USB cable that you can use to recharge it during a power outage.

To recharge it using this method, follow these steps:

  1. First, you need to remove the thermostat from the wall.
  2. Plug the USB cable into a computer or a wall charger.
  3. Connect the other side of the cable into a Nest’s charging port on its backside.

It will take about 2 hours to charge your Nest thermostat. However, it may take a shorter time if the battery still has some charge.

Here is a 2-minute video showing how to charge this device using a USB cable:

Using the Common Wire

You can also install the common wire (C-wire) to provide a constant power supply to your Nest thermostat. This is the ideal method to use if your HVAC equipment keeps failing.

However, this process is complex – you may require an expert’s help to run the cables from the HVAC equipment directly to your thermostat.

Note: Ensure the Nest thermostat is off position when using this approach; otherwise, it won’t charge.

Check out: Nest Not Cooling To Set Temperature: 7 Causes & Fixes

How To Check the Battery Level on Nest Thermostat

Checking the battery level on your Nest thermostat is one way of knowing if your device is functioning as it should. 

Sometimes it brings up a low battery notification even when it’s connected to a power source.

In most cases, it is an indication of faulty wiring, or maybe you are using the wrong adapter.

That said, I recommend that you always check the battery before attempting any quick fixes.

To check the battery level, follow these steps:

  1. Touch the Nest icon on your thermostat’s screen.
  2. The battery level will appear at the bottom of the screen; if it shows anything other than a full battery, you have to change the batteries.

In some cases, you need to navigate the settings, the technical info, and then power settings to find the battery level.

If it is below 3.6V, it means your battery is deficient, and very soon, the device will disable the Wi-Fi connection.  If it is above 3.8, then your battery is working fine.

How Long Does Nest Thermostat Last Without Power?

The Nest thermostat can last without power for 1 to 2 hours before gradually shutting down. As the battery drains, the thermostat disables the Wi-Fi connection in an attempt to preserve more power. However, it comes at a cost as the Nest loses its smart functionality.

Nest thermostats require power to work; however, they also have a rechargeable lithium-ion backup battery that kicks in the event of a power cut. 

While your thermostat will keep working, the loss of Wi-Fi makes it impossible for you to control the heating in your house from a remote location.

You might also like: Why can’t I connect the Nest thermostat to the app?

How To Prevent It From Shutting After an Outage

Nest thermostats make your life easier.

You don’t have to manually reset the HVAC equipment every time the temperature is unfavorable.

But with constant power outages, your Nest thermostat might fail to give the best results.

To make the most of your Nest thermostat, I recommend that you follow these guidelines.

1. Replace Your Batteries

Although replacing your batteries doesn’t guarantee that your Nest thermostat will work continuously, new batteries last longer than old ones. 

More so, it is an effective solution if you’ve been receiving constant low battery notifications.

Caveat: Replacing your batteries voids your Nest warranty. Therefore, I advise that you troubleshoot the device several times before using this method. 

Also, ensure the replacement batteries are compatible with the device to avoid damaging it.

2. Use the Uninterruptible Power Supply (UPS)

If your neighborhood frequently experiences power outages or low voltage, you might want to invest in a UPS.

Also known as battery backup, the UPS provides power backup to your electrical appliances when the primary power source fails.

However, the UPS doesn’t promise an unlimited power supply. Remember, it’s only a power backup system bound to drain after several hours of usage.

More so, if you experience long hours of a power outage, your UPS will drain to the last bit as it attempts to keep your devices and equipment on.

If you need a UPS power backup for your Nest thermostat and computers, I recommend this APC UPS power backup from It comes with 7 power outlets and 1 USB cable outlet for your phone and other devices.

3. Use the Nest Thermostat With Solar Power

Nest thermostats can draw power from the batteries charged using solar panels.

With this technology, your Nest thermostat remains functional throughout. 

The beauty of using solar power is that you don’t have to face the hassle that comes with a power outage – solar gives you more control over your home’s power supply.

For example, you can easily switch to solar if your residential area’s distribution lines are off, ensuring your Nest device continues to function without interruptions.

Bottom Line

Your Nest thermostat will work without power for a short time until the battery drains its charge. In the process, it disables the Wi-Fi connectivity and on-screen notifications.

In its power-saving mode, the Nest thermostat is no longer a smart device. 

It becomes impossible to access the system remotely, and you’ll have to input the commands to the Nest thermostat physically.

However, you can increase the time the Nest thermostat stays operational after a power outage by:

  • Replacing old batteries
  • Using an Uninterruptible Power Supply (UPS) unit
  • Powering the thermostat using solar power

Read also: Why Does My Nest Thermostat Say “Delayed for Two Hours”?