Nest Thermostat Gen 4 Battery Life

[ConDog]

Hi, looking to purchase the Gen 4 Nest Thermostat but I do not have a C-Wire (Just a 2 wire low voltage setup) and wondering if anyone has any experience with how long the two AA batteries would last between swaps. Will i get a fee months with a good set of lithium batteries? Is there a power cable i could attach to a nearby outlet?

[jenniffert]

Hi ConDog,

Thank you for posting in the community! I'm happy to assist you with your Nest Learning Thermostat 4th Gen. compatibility concerns regarding the common wire.

Since you mentioned having only two wires, could you please share a picture of your current wiring setup?

Regarding your questions about whether you’ll get a few months of good battery life with lithium batteries, here are some details:

• Nest Thermostat: This model uses alkaline batteries and may require battery changes every three months. For more information, you can check out this article: Batteries for Nest products.
• Nest Learning Thermostat 4th Gen:This model needs consistent power to avoid draining its internal battery. If the internal battery does drain, the thermostat will need to be recharged using a USB-C cable.
  
  

Additionally, in most cases, Google Nest thermostats can charge their built-in batteries using your heating and cooling wires. But there are situations where you may need to connect the Nest Power Connector or a common or C wire to consistently deliver power to your thermostat. To learn more, you can see this article: Learn about the common or C wire.

Let me know if you have more questions.

Best regards,

Jenniffer

[ConDog]

Our thermostat has an “R” wire supplying power that I assume is 24v and a W wire that doesn’t have voltage. From what I understood the 4th Gen learning thermostat took AAA batteries but how long is the life expectancy of the rechargeable lithium battery if it’s on a low-power system without a C-wire?

[jenniffert]

Hi ConDog,

Thanks for the reply!

I'm sorry for the delay in response. I'd be happy to help with your concerns!

Since you mentioned having only two wires (power and heating), Nest thermostats are designed to use very little power. So even though Nest thermostats have Wi-Fi activity sensors, color displays, and more, they typically don't need a C wire to stay charged up.

However, in some cases, the thermostat's internal battery wouldn’t be able to keep the thermostat on, especially when the C-wire is missing. This can lead to power errors and eventual shutdown.

At this time, the best recommendation is installing a common wire or Nest Power Connector. To learn more, you can check out this article: Nest Power Connector.

Please keep me posted.

Best regards,

Jenniffer