Hi Itp,
Thank you for posting in the community! I understand your Nest thermostat's battery is losing power even though it's permanently connected to a USB charger. This is certainly not typical behavior, and I can see why that would be concerning.
To help me understand and resolve this issue, please provide a bit more information:
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What specific Nest thermostat model do you have? If you're unsure, this article can help: How to tell which Nest thermostat you have.
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Why are you using a USB charger for permanent power? Is your thermostat not connected to a C wire from your HVAC system?
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Have you tried a different USB cable and/or power adapter to rule out a faulty accessory?
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When did you first notice this problem starting?
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Have there been any recent changes to your home's HVAC or electrical system? (Such as recent repairs, power outages, or new appliance installations, which can sometimes play a role.)
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When was your thermostat originally installed?
For context, here's how Nest thermostats typically get power:
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Most Nest Learning Thermostats and Nest Thermostat E models are designed to be primarily powered by your HVAC system's wiring (specifically the 'C' wire) to keep their internal battery charged. The USB port on these models is mainly for initial setup or temporary charging if system power is insufficient.
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The newer Nest Thermostat (sometimes referred to as 4th Gen) can be powered continuously by a USB charger if a C wire is not present.
Once I have a better understanding of your Nest Thermostat model and your setup, I'll be able to investigate further and provide more targeted help. I look forward to your response!
Regards,
Humberto
