Do thermostats need batteries?

Yes, they do.

 Batteries in thermostats are more than just a power source. They act as energy storage and a backup source to retain programmed schedules in case of power outages. Therefore, even today the 24-volt c-wired digital thermostats also have a battery compartment. Manufacturers encourage the use of batteries for this reason. 

What’s the need for an energy backup in a Thermostat?

Batteries act as a secondary power source for digital thermostats, similar to how UPS helps a computer during a power outage. It saves the program and leaves you from the time and effort in resetting the thermostat’s settings that get erased in such unprecedented events. 

If you program the schedule for the week beforehand, losing them would mean relying on your memory to set all the energy-efficient settings on the thermostat. It could be a cumbersome and frustrating task to get done. 

Batteries save you from such time-consuming tasks, so you can enjoy a cozy home once the power is restored at your home. 

Without a battery backup, you may find your programmable thermostat working inefficiently.   

It makes the readings inaccurate and negatively affects the temperature and time settings. It, in turn, reduces the energy efficiency of your heating unit, thereby nullifying the whole point of installing a smart thermostat at your home.

How to know if your thermostat needs a battery change?

If you have a digital thermostat, you would know that it operates either by batteries along or hard wired to 24-volt c-wire or by a combination of both. 

Usually, most thermostats operate on a hybrid system that uses direct electricity by default and batteries only during power outages. In such hybrid operated thermostats, a low battery alert goes off whenever the batteries start to drain out. 

Apart from the alert, you can also look out for signs like:

  • Blank touchscreen display 
  • Unprogrammable HVAC system, and/or thermostat 
  • Odd characters on the LED screen displays
  • Red/ empty on/off flashing battery icon displays 
  • Sudden decline in the performance of air-conditioning unit or furnace

In this age of the Internet of things, you can easily set up alerts to receive battery change notifications via email or text message. You must replace the batteries before it drains out completely and starts affecting the performance of your HVAC system.  

Another way to know more about battery change is to refer to the instruction manual of the thermostat. Most manufacturers give an explicit regular battery ri020-20nt schedule. A yearly change of battery might be ideal depending on the thermostat model.  

How to Change Thermostat Batteries?

Once in a year or so, your thermostat may need a battery change. You must look out for the signs mentioned above. If you see anything similar, you will know, your thermostats need a battery change. 

But, how do you do that?

The first and foremost step is to make yourself aware. Get the instruction manual and read it thoroughly- if you are changing it for the first time. 

Even though the steps to change batteries differs for every other thermostat, we have listed some general guidelines that you must follow, no matter what kind you have. 

Before changing the batteries you must:

  • Gather your tools:

Equip yourself with the required tools like a small flat blade screwdriver. Keep it within your reach before you start changing the batteries. 

  • Get Right batteries

Check your manual to know the right kind of battery for your thermostat. It could be either AA or AAA alkaline or Lithium batteries. 

You must ensure the batteries are in good condition without any leaks or visible damage.

Steps to change batteries:

  1. Pull-off the thermostat housing
  2. Check the battery slots
  3. Turn it over, if necessary.
  4. Use a screwdriver to remove old batteries
  5. Place the new batteries in the slot
  6. Cover the thermostat 
  7. Mount the thermostat on the wall. 


Never install damaged batteries. Always ensure that you use fresh batteries. A battery with leaks and dents can potentially cause damage to the electronic component of the thermostat. It also alters the temperature settings. 

Even a degree change can hamper energy consumption. Therefore, a change in temperature settings due to poor battery quality can increase your energy bill as well. 

Will the thermostat work without batteries?

Some of the modern digital thermostats that are hard-wired to your home circuit can work without batteries. These thermostats may have battery slots. Here, the batteries act as a secondary power source and energy storage during a power outage. 

We have listed some of the thermostats that work without batteries:

  1.  Honeywell Wi-Fi Smart Thermostat
  • Requires C-wire
  • 7-day programmable 
  • User-friendly touchscreen.
  • Customizable programs to fit your schedule 
  1. Wyze Smart Wi-Fi Thermostat
  • Requires C wire
  • Compatible with Amazon Alexa and Google Assistant.
  • Sleek, black design
  • Remote access to the thermostat via phone app
  1. Honeywell Home Wi-Fi 7-Day Programmable Thermostat (RTH6580WF)
  • Remote access to total Connect Comfort app 
  • A big, backlit digital display and easy controls make for a user-friendly experience.
  • Learns your schedule
  • Requires C-wire
  1. Google Nest Learning Thermostat
  • Self-learns your programs
  • Home and away assist feature
  • Remote control via Nest app
  • Leaf icon indicates the energy-saving temperature
  1. Ecobee Lite Smart Thermostat
  • Compatible with smart homes
  • Saves up to 23% on HVAC costs annually
  • Remote control via ecobee app
  • Requires C Wire


Batteries are the fuel that keeps the thermostat running without any glitch. Even when you install hard-wired thermostats, it is always advisable to use a battery as a secondary power source. It not only saves your time and effort to reprogram the device after a power outage, but it also ensures healthy thermostat operation. 


Comments are closed.