How Long Do Batteries Last In A Thermostat?

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If your thermostat doesn't work, it can't control your home climate control. As a homeowner, you may be wondering how long the batteries in your thermostat last. Fortunately, we have done the legwork for you, and here's what we discovered.

Thermostat batteries can last for 8-12 months but some can last up to five years. Low batteries in thermostats are common problems that may lead to the inefficiency of your home's heating and cooling system.

Most programmable thermostats show a low battery symbol when the batteries start running low.

The batteries in your thermostat may stop working if they exceed their life expectancy and needs replacement. Continue reading to get more detailed information about thermostat batteries.

Thermostat set to 77 degrees, How Long Do Batteries Last In A Thermostat?

Life Expectancy Of Thermostat Battery

When buying a thermostat battery, you should consider how long it can last. Thermostats are powered by different types of batteries, ranging from small button cell batteries to lithium batteries, which can also power other devices.

Some thermostats use AA or AAA alkaline batteries, while others use CR2032 3-volt lithium batteries.

Some thermostat batteries may last up to five years, while others can for 8-12 months, depending on the type. Even though your thermostat is hardwired, it is likely to have a backup battery that needs replacement from time to time.

The backup battery allows your system to function even if the power system fails. Low batteries in digital thermostats can prevent your home's cooling system from working.

How Do I Know My Thermostat Needs New Batteries?

Before replacing the batteries in your thermostat, you should be sure your thermostat actually needs new ones.

A thermostat set to 68 degrees on a white background

Your thermostat usually gives some signs when the batteries are running low. It is better to change the batteries before they die. Some models display a warning sign about a month or two before the battery dies.

Aside from a blank screen on the thermostat, another clear sign that you need to change your thermostat batteries is when your cooling system isn't in working order. The batteries in thermostats should be replaced once a year on average. 

Best Batteries For Thermostats

Most thermostats still rely on batteries, while others get their power from your home's electrical devices or HVAC system. The following are the best batteries for thermostats:

1. AA Alkaline Battery

This is the most common thermostat battery. AA battery consists of two electrodes and a metal or carbon rod called an anode. The anode has a negative charge, while the cathode has a positive charge.

When the battery is inserted into a device, these charges cause electrons to flow from one electrode to another, which creates energy that powers the device.

The AA battery can send power to the thermostat and provides backup power in case of power failure.

Despite the fact that the majority of modern gadgets have built-in batteries, there are still some household devices that use AA Batteries. Devices like remote controls, calculators, clocks, and radios use AA batteries.

Click here to see this Duracell AA alkaline battery on Amazon

2. AAA Alkaline Battery

This battery is known as a triple-A battery. The AAA battery is a small-sized, low-voltage alkaline battery.

It is also suited for thermostats because it can be easily installed and removed. They are known to be efficient and long-lasting. AAA batteries can be used to power different types of devices.

This battery has a lot of benefits that make it the go-to option for many people. One of these benefits is its long shelf life. Alkaline batteries are more powerful than zinc-carbon batteries, but they are not rechargeable.

Click here to view this Duracell AAA alkaline battery on Amazon

3. 3V Disc-style Lithium Battery

Another battery used for the thermostat is the 3v disc-style lithium battery.

Only 70-80% of the original energy can be stored in this battery. They can be used to power small electronic devices like calculators, wristwatches, and different medical and fitness devices.

The 3V disc-style lithium battery stores energy for use in a thermostat. It is meant to be used with the thermostat’s temperature sensor and controller board.

This battery has a voltage of 3 volts and it is used to power a thermostat because it has a low discharge rate and is also durable.

 A thermostat needs constant power which a 3V Disc-style lithium battery can store. Despite the fact that lithium batteries last longer, their voltage usually drops over time.

Click here to see this Duracell 3V lithium battery on Amazon

What Happens When Thermostat Batteries Are Low?

When low batteries die, the display screen will go black, as a result of this the thermostat will stop working as well as the cooling units.

To avoid this problem, you have to be observant to know when to change the thermostat batteries so it won't run down completely

Can A Thermostat Run Without Batteries?

Modern smart thermostats are wired directly to the grid because they require so much power. A modern thermostat can work without batteries. The smart thermostat does not need batteries to work.

If no batteries are inserted, the thermostat will most likely run on AC power (as indicated by the caution sign and low battery flashing on the display).

Most digital thermostats are both hardwired and have a backup battery. The purpose of backup batteries is to preserve any programmed schedule when there is a power failure.

Why Does My Thermostat Battery Keep Dying?

You might be wondering why your thermostat battery starts dying after some time. The reason for this could be that the battery is either old or faulty.

The temperature settings you program into the digital wall thermostat have no bearing on battery consumption.

For example, if you decide to turn down the air conditioner during the summer, this will not extend the life of the battery in your thermostat; you will only end up reducing the price of your electricity bills.

Man setting the thermostat to 78 degrees

Furthermore, if your thermostat battery continues to die after a short period of time, it is likely that you are not using a good battery.

You should see a battery compartment on the side, back, or beneath a sliding panel with space for two or more AA or AAA batteries, depending on your cooling system.

Most thermostats are incompatible with rechargeable batteries because they do not deliver the appropriate voltage, so it is better your stick to single-use options.

Why Is My Thermostat Not Working After Replacing The Batteries?

A white thermostat set at 80 degrees

Sometimes, after changing the batteries in your thermostat it may stop working. It is best to check for some minor issues. This problem may arise when your batteries are not properly installed.

Always double-check the battery space to make sure they are well installed. Try realigning the batteries to get them facing the right way. The markings in the battery space can help you with the orientation.

To change the batteries of some thermostats, you may need to remove the body of the thermostat from the base.

After removing the case, you can easily loosen and remove one of the small wires. These wires are attached to the HVAC unit and allow the thermostat to interact with the HVAC unit. 

Furthermore, consult your thermostat manual to make sure you are using the appropriate type of batteries.

If the thermostat refuses to work after all these, try resetting the system and check if any part of the thermostat is damaged. You can also check if there are any visible wire issues.

Final Takeaways

Thermostat set to 77 degrees

A thermostat is a device that automatically regulates the temperature in a house or building and it can be controlled by a central heating system, an air conditioning system, or other devices.

The battery life of thermostats varies depending on the type of battery, age, and usage. It can last anywhere from 8-12 months or more.

When your battery starts running low, you will receive a signal so you have to be alert. Your cooling system will stop working if the battery runs down totally. You have to be mindful so you will know when to replace the battery.

If you found this post helpful, be sure to check out these similar articles you might like:

Do Lennox Thermostats Have Batteries?

How Long Does A Nest Thermostat Last? [Inc. The Battery]

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