When setting the temperature on your thermostat, you may notice that has a panel for batteries. Most programmable thermostats have a panel for batteries. Some of them use AA batteries, whereas others use AAA batteries. You can remove the facing on the panel, insert the appropriate batteries, and snap the facing back onto the panel.

Thermostats, of course, are hardwired to the homes and buildings in which they are installed. They run on electricity – but they use the electricity of the home or building’s main power supply. Thermostats don’t run on electricity from batteries. Assuming your thermostat is hardwired to your home, you might be wondering why it has batteries.

Batteries Save Programming Data

The reason thermostats have batteries is to save programming data. Programmable thermostats allow you to set heating and cooling schedules. You can program them to achieve and maintain different temperatures at different times. If your home is unoccupied during the midday hours, for instance, you may want to program the thermostat for a lower temperature during the winter and a higher temperature during the summer.

When you program your thermostat, it will store this data internally. Batteries ensure that if the power goes out in your home, the programming data will be saved. The batteries will provide backup power to the thermostat, thereby saving the programming data. Without batteries or with dead batteries, on the other hand, the programming data may be lost in the event of a power outage.

There are some thermostats that require batteries to run. Smart thermostats, for example, may not run without batteries. Thermostats that are hardwired to a home or building’s main power supply typically don’t require batteries. Thermostats that aren’t hardwired to a home or building’s main supply, conversely, will usually require batteries.

How to Replace the Batteries in Your Thermostat

Whether your thermostat uses AA or AAA batteries – or if it uses 9-volt or lithium batteries – you’ll eventually need to replace them. Batteries don’t last forever. Over time, they’ll lose their charge. Fortunately, you can easily replace the batteries in your thermostat.

If the batteries in your thermostat are dead, remove them. The battery panel is typically located at the bottom or on the side of most thermostats. You can pull the front of the panel off, after which you can remove the dead batteries. After removing the dead batteries, replace them with new batteries of the same type.