Nest Thermostat Li Ion Battery replacement

[Spoonbill]

I am trying to assist a friend whose Li Ion battery has gone bad.  This is the thin, flat, 3.7 V, 2.1 Wh battery.  I am tryin to determine which way the flat connector attaches to the receptacle. The connector has red, white and black wires attached to it but which way is it connected ( red towards the battery compartment or Black towards the battery compartment? I 9 we don't know the vintage but have the S/N if that would help

Thanks in advance for your help!

[CoolingWizard]

@Spoonbill ,

The Nest Learning Thermostats are not designed for consumer replaceable LiOn batteries. If you have disassembled the unit to replace the battery and failed to note how the battery was wired this is unfortunately a problem you’re going to have to solve on your own. Once again, these system displays were not designed to be disassembled and replacing the battery

The Cooling Wizard

[Spoonbill]

Cooling Wizard, 

Many thanks for the feedback.  The unit is a 3rd Gen. unit.  I’ll just disassemble and try reversing the position of the connector.  As a side note, unrelated to this post, would you be available for a short conversation on an unrelated commercial HVAC  topic?  

[Patrick_Caezza]

@Spoonbill 

None of Nest's thermostats have field-replaceable batteries except for the Google Nest Thermostat (2020), and attempting to replace one will void the warranty.

Also, no battery sold anywhere will work correctly in any of the thermostats. Sellers on Amazon and eBay claim they have one for sale that works in a 3rd Gen Learning thermostat, but it's a false claim, as it is the wrong physical size and voltage.

There is no reason that a 4th Gen Learning Thermostat would need its battery replaced, as all are still under their factory warranty.

[Spoonbill]

Patrick, thank you for the note. This is a 3rd generation model, and the replacement battery id the correct voltage but  slightly  higher Mh which is not a problem.  The physical size is correct and the battery is replaceable, but I’m trying to figure out if I have the connector right side up or down.

[CoolingWizard]

@Spoonbill ,

Sure thing. Just post your question. I will do my best to answer it. 

The Cooling Wizard

[Patrick_Caezza]

@Spoonbill 

You're not understanding the answers.

Yes, you can open up the thermostat

Yes, you can get a "replacement" battery off the internet

But,

The batteries being sold are the wrong voltage and VA rating.

Will it Work? Probably, but you will have issues down the road.