Skip to Content

Nest Thermostat Low Battery: 7 Easy Ways To Fix It (2022)

Nest Thermostat Low Battery Fix

Nest thermostats are designed to charge on their own. Neat, isn’t it?

Low-maintenance. Doesn’t require much supervision. Just a goldfish pet.

But what if your Nest constantly bugs you? Flashing that “low battery” message non-stop?

No, your Nest thermostat isn’t haunted.

So what could be causing this strange activity?

Read on to learn:

  • Why your Nest thermostat say “low battery”.
  • 7 quick ways to troubleshoot and fix these issues.
  • Why your Nest thermostat shouldn’t need charging.
  • And many more…

Why does my Nest thermostat say low battery?

Your Nest thermostat says “low battery” because it’s not connected to its base. It can also be due to broken or old batteries. Or the battery has run out. The main grid may not get enough power because of faulty wiring. Also, dirty air filters drain your battery.

How do I fix my Nest thermostat with a low battery?

You can fix your Nest thermostat with a low battery by putting it in its base correctly. Changing the batteries can help. Another way to boost the power is using a C-wire or a Nest Power Connector. You can also keep your filter systems clean. Use low-power modes and charge with a USB cable.


Nest thermostat low battery – 7 fixes


#1: Secure it on the base

Your Nest thermostat could be hanging on a thread. It’s too loose to receive power from the base. This could be why it tells you your battery is low.

Can I call it… SUPER BASE?

The base is the most important part of the Nest thermostat. It has all the wires that move the electricity along.

The base connects the thermostat to the main power source. This automatically charges it when needed.

Check if the Nest thermostat is tightly pinned onto the base. If not, tightly attach it back. You’ll hear a “click” sound when secured.

Read also: Nest Thermostat Won’t Charge: 7 Causes & Fixes

#2: Change the batteries

That one Biology fact that turned into a meme: “The mitochondria is the powerhouse of the cell.” You thought it was pointless?

Guess what? The battery is the powerhouse of your Nest thermostat.

In every device, the battery wears out as it ages. This is due to constant charging. Or simply because it’s used 99.9% of the time.

“How do I know my battery is too old?”

Is your battery old enough to be in preschool? If yes, take out the cap and gown. It needs to graduate.

Your battery’s average lifespan is five years. Especially if it’s used as your thermostat’s main power source. A backup battery can go for longer.

“So do I chuck it in the trash?”

Hold up. All devices have this thing called a warranty. Your Nest thermostat has one too.

The Nest E and the regular Nest thermostat are covered for a year. The Nest Learning is warranted for two years. It can be extended, though. Only if a NestPro installed your device.

Note: The warranty no longer works if you:

  • Mishandled the device.
  • Broke it due to repairing it yourself.
  • Changed any of the internal parts (except removable batteries).

How do I change the batteries?

The Nest thermostat has an option for backup batteries. You could have already used a pair but it has run out. Or this is your first time.

Pull the Nest thermostat out of its base. Remove the back cover. Take out the old batteries, if any. Put in two new 1.5V AAA alkaline batteries. Get high-quality ones from a reliable brand. Close the cover and return the device to the base. It should click when secured.

The Nest Learning and Nest E thermostats use lithium-ion batteries. Some users tried removing its internal battery. Most likely, to save money by replacing it themselves. But this is a bad idea.

Don’t risk breaking your thermostat. Contact a NestPro in your area.

#3: Install a C-wire

A C-wire isn’t *really* necessary to install a Nest Thermometer.

However, having one could be handy. Especially when your thermostat keeps screaming for help.

This added power source keeps your thermostat on. All-day long. No interruptions. As this keeps the electricity flowing.

How much power does a Nest thermostat need?

Your power source must be higher than 3.6V. This keeps the thermostat charging. This feature also avoids a “low battery” issue.

Below 3.6V shuts down Wi-Fi and delays software updates.

In this case, your main power could be the problem.

You don’t need a complete do-over. This is where a C-wire comes into play.

Are you a C-wire newbie?

If you’re about to buy one… Make sure your power source is enough.

The Nest thermostat follows the Voc, Vin, and lin values. This measures the power sent to your thermostat. The values depend on whether you use a C-wire.

Note: You can see more information on your device. Tap Settings and select Device Information.

For a C-wire, you’ll need:

  • Voc: 29 to 42V.
  • Vin: 29 to 42V.
  • lin: 100 or 200 mA.

These values should be steady. This keeps your thermostat working smoothly.

If your device already has a C-wire, check if it is:

  • Tightly secured.
  • In good condition.

Is your C-wire showing any wear and tear? Any fraying? Discoloration? Or burned parts? Replace it with a fresh one.

Also, make sure the C-wire is connected to the C-space. That way, the power can move through your device.

“But what if I don’t have a C-wire?”

Is the C-space empty in your main grid? This is a sign for you to add one (As if the current issue isn’t reason enough.)

You can either set it up yourself like a genius (or a madman, whichever side you’re on.) Or you can go on the safe side and ask for help.

Either way, be prepared for additional costs.

“I don’t want to lose my warranty.”

Fair enough. Contact a NestPro in your city. These pros can assist you with any technical issues. On days when your thermostat can sense your fear. And most especially, when your device needs a C-wire.

#4: Install a Nest Power Connector

$90 to $135-that’s the cost of a C-wire installation.

You hear that sound? It’s your wallet crying for help.

Fortunately, Google introduced a low-cost alternative. It’s called the Nest Power Connector. For just $24.99 and some basic DIY skills. Definitely a bang for your buck.

Official Google products can also avoid further damage. Some C-wires that say “Nest compatible” can still cause issues. Better be careful.

How does it work?

It works exactly like a C-wire. It provides consistent power to your Nest thermostat. That should get rid of the “low battery” warning.

“How do I install one?”

No drilling or wiring is needed. Just your common sense and patience.

Before getting one, ensure that:

  • Your Nest thermostat is compatible. 
  • Your circuit breaker is shut off.

The Nest Power Connector works with 24VAC HVAC systems. Millivolt or high voltage systems are incompatible.

When installing, turn off your house’s main power.

Watch this instructional video:

First, update your Nest thermostat. It should be able to recognize a new device. In this case, the Nest Power Connector. You can do this in Settings. The Nest E and the Nest thermostat 3rd Gen don’t require this step.

Then, find the control board in your HVAC. If there’s none, look for thermostat wires.

Label the wiring using sticky tape. Connect the wires to their pairs. Close the HVAC cover. Then, turn on the power.

“Why should I get a Nest Power Connector?”

It’s cheaper than a C-wire. You don’t need to contact an electrician. Plus, it gets your device running all the time.

You also don’t have to risk breaking your warranty.

#5: Use an external USB cable

Nest Thermostat External USB Cable

You’ve changed the batteries. You’ve added a C-wire. You stuck it like super glue to the base. You couldn’t get a Nest Connector.

“Why is being an adult so hard?”

Before you start pulling your hair…

Your last resort is plugging in a USB cable. This is just a temporary fix. Charging it externally for long periods could damage the battery.

The Nest Learning thermostat (1st Gen) needs a mini-USB cable. While a micro-USB cable for the Nest thermostat E. The Nest thermostat has no USB port.

How do I charge with a USB cable?

Take off the thermostat screen from the wall. Attach the USB cable. Plug in a power source. Then, charge for 4-5 hours.

This should silence the hungry zombie in your thermostat. At least for a while.

#6: Use energy-saving modes

Admit it. You’ve never read the thermostat’s manual.

Heck, you might still be in the getting-to-know-you stage with your device.

Did you know? Your thermostat has built-in energy-saving modes.

These can extend your battery life. Also, optimize the use of your device. And even prevent the “low battery” issue as well.

There are two modes:

  • Off Mode.
  • Off Eco Temperatures.

When should I use these modes?

Running errands for a few hours? Or you don’t mind a little change in the air just to save power? Eco Temperatures should work for you.

For a week or month-long trips away, Off Mode is better.

How do I activate Eco Temperatures?

Eco Temperatures can be set manually or automatically.

On your Nest or Home app, select Away. Your thermostat will detect that nobody’s home. Then, it automatically sets to Eco Temperatures.

To change it manually, open your Home or Nest app. Select thermostat, then Settings. Choose Preset and tap Eco.

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

How do I activate Off Mode?

Off Mode doesn’t shut down your device 100%. But it maintains your home’s safe temperatures. It also stays online. So you can control it with the app.

To do this, press and hold the touch bar. Turn Off will show on the screen. Slide the touch bar to Turn Off. Once more, press the touch bar.

Your wallet will surely thank you after this.

#7: Clean your filtration system

When was the last time you replaced your air filters?

If you say, “What?”, then you might want to check them. Like right now.

Your home’s air systems have vents. Air passes through them all over the house. Also, these vents have filters that remove dust and molds from the air.

But when left uncleaned, the dust piles. Then, hot air builds up. This causes your thermostat to work twice as hard. This can drain its battery twice as fast.

Like #6, this step prevents more damage to your battery.


Is it normal when my Nest thermostat says Low Battery?


It’s really worrying when your Nest thermostat shows “low battery.” This device is directly connected to your HVAC system. So technically, it should be always charging.

“But if that’s the case… Why is there a battery in the first place?”

*cue X-files music*

The battery powers the Nest when there’s a blackout. It can last up to two hours. That way, your house stays soooo cozy. You won’t even bother going outdoors anymore.

“I followed all these steps. But my thermostat is still grumbling!”

Buying a new one would be the best bet.

“Low battery” is indeed a minor issue. And Nest thermostats were made to last for 10 years!

If the NestPro still can’t fix it, consider getting a new one.

“I just bought this last week! Get me a manager!”

Don’t be a Karen! Remember, this device comes with a warranty.

You can contact support and file a warranty claim. You can get a refund if the issue fits their terms.

You’ll have to return the product. They will cover the shipping costs. Your concern will go through an examination. But if it doesn’t fit the warranty terms, you must pay for the shipping.

“Well, how long should a Nest thermostat last?”

A Nest thermostat should live up to 10 years. It’s still a new device. So there are not enough studies to back this claim.

Better take good care of your Nest. What better way to prove it than to do it yourself.

You may also wonder: Are smart thermostats universal?