Nest Thermostat Battery

Outline	Model	Type	Capacity	Price	Order
	CS-NLT100SL Generic T100577 TL363844 1st Generation	Li-Poly	3.7v 200mAh 0.74Wh	$32.00Cdn ($25.60US)	Quantity:
	CS-NLT200SL Generic A0013, GB-S10-284449-0100, T3007ES, T3008US, T4000ES, 284449, F04247, F04644, 3T254C, TL284443 2nd & 3rd Generation	Li-Poly	3.7v 380mAh 1.41Wh	$32.00Cdn ($25.60US)	Quantity:
	CS-NLH700SL Generic Connect, A0078, H17, A3GT2001H, 082-00029-00 Range Extender	Li-ion	3.7v 700mAh 2.59Wh	$35.00Cdn ($28.00US)	Quantity:

Installation instructions can be viewed here.

The above batteries will have different model numbers on the product pages since they are after market replacement batteries which are often as good or better than the originals.  The current or mAh (milliamp hour) rating of a battery is an indication of the battery capacity or how long it will last on a charge, the higher the better.