5 year old Nest Learning Thermostat has trouble staying charged

[Brion]

One of my Nest Learning Thermostats just started flashing a red dot after 5 years of working fine. I can charge it via a USB charger and that works for about 36 hours and then we are back to red dot. I have not recently changed anything in the HVAC system this unit controls. I have another Nest Learning Thermostat that is 6 months older and controls another furnace and AC and it is still running fine. It isn't clear what changed to cause this. The battery does still take a charge via USB, so I don't think it is bad batteries, but clearly the unit is not liking the power it is getting from the wiring we have had for many years and that was working fine. Both thermostats saw new AC units installed 3 years ago and that is the last change we had in this house's HVAC (two independent systems).

Do I need to replace the thermostat every 5 years or so?

[Brion]

Since nothing has changed in my home heating/air conditioning for years, I suspected my Nest Learning Thermostat was the problem. I ordered a new one and installed it. It has been working fine for over a week now without needing to be manually charged up every few days. This has resolved my issue, but means my Nest Learning Thermostats do not last more than 5-6 years before they stop self-charging.

[Brion]

Note that I plugged the new one into the old base without issue.

[jenniffert]

Hi @Brion,

Thanks for reaching out here in the community. I'm sorry for the delayed response.

Many factors can affect the Nest thermostat, including usage, battery life, and external factors like power surges or extreme temperatures. Troubleshooting can take time due to these factors.

I'm so glad to hear that your new Nest Learning thermostat is working well now. However, if you have any further questions or concerns, don't hesitate to reach out to us. 

Best regards, 

Jenniffer