Nest Thermostat Not Charging... works on different base

[WorstBirder]

This is a 3rd Gen Nest.  I have had it installed and operating for 3+ years (both heating and cooling, wires connected are: Y1 G Rc W1 and Rh).  I noticed my downstairs one needed charging and I have concluded that it is not the device itself because an alternate device won't hold a charge in that location either.

Summary: I have two thermostats and neither of them will hold a charge on one of the bases.  So I know it is not the Nest itself (they both work fine in other locations). 

Both the air conditioning and heating systems still work while the device has a charge.  The condensate line for the AC is not clogged. 

I have no idea what to do.  Please help!

[Ashepherdson]

Sorry a little clarity is needed, Do you have two nest thermostats to run one HVAC system?  Or two HVAC systems, each with its own device?  

IF you are running two thermostats on one system, then one may not be getting enough power to stay charged, which is causing the issue. Another thing I noticed is that you did not mention if you have a C wire, which is what the thermostat uses to draw power.  If you do not have a C wire, then the thermostat would only charge when the system is on, and again depending on your setup may not be able to draw enough to charge fully.  

[WorstBirder]

They are running on the same heating system but two different AC systems.

The upstairs location has a C wire, and both devices work properly there.  (When either Nest device is docked to the downstairs it eventually dies, they both maintain a charge in the upstairs location)

I recently swapped the screwed to the wall base to see if maybe the pin connector is the issue.

My main point of confusion is that these Nests have been working flawlessly for 3+ years.

There was a powerful electrical storm where power was lost and came back within 2 hours about 2 weeks back... this kind of corresponds to the beginning of the problem but also seems like coincidence. 

[Ashepherdson]

Can you fully charge both units and put them back in place once charges, then monitor the voltage in the nest app under technical information .  See if the downstairs one starts dropping below 3.89 v (standard voltage).  If it does, then you may need to install a C wire adaptor, of which there are many options for online.  

The reality is without a C wire the thermostat would only get power when the heat or cooling is running, and it could be that they have not run as much as previous years and are thus draining .  

[WorstBirder]

I tried fully charging them.  They air conditioning has been on a lot this summer.

The voltage is usually in the 3.6-3.8 range... Nest support said this is fine but yes it does seems low.  C wire adaptor is my next step I guess.  I was also considering cleaning up the wiring a little to remove any corrosion that there might be.

[Ashepherdson]

If you are comfortable cleaning the wires safely (on both ends of the connections of course) , then that would be an ideal next step!  Sorry couldn't be of more help, it does seem like an odd situation .  It's possible the power outage had something to do with it , but I believe that might be more of a coincidence

[Ashepherdson]

completely forgot google has this:

https://store.google.com/product/nest_power_connector?hl=en-GB

[Jake]

Hey all,

I wanted to reach out and see if you are still in need of any help? Please let me know, as I would be more than happy to look into the issue further for you.

Best regards,

Jake

[Jake]

Hey all,

It's been a few days since the last reply. I am going to lock the thread at this time and if you have any questions, please feel free to create a new post. 

Best regards,

Jake