In the models here, a smart lock takes 4 AA batteries, fitted on the inside of the door. The August Wi-Fi Smart Lock takes 2 CR123A lithium batteries instead, and Level locks a single CR2.
Which lock?
The battery it takes
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Smart lock batteries by model
| Lock | Battery | Battery life, maker’s figure |
|---|---|---|
| Schlage Encode | 4 AA alkaline | Up to six months |
| Schlage Connect | 4 AA alkaline | Not listed |
| Kwikset Halo | 4 AA | Not listed |
| Kwikset SmartCode, Signature Series | 4 AA, in a battery pack | Not listed |
| Yale Assure | 4 AA | Up to one year |
| Google Nest × Yale Lock | 4 AA alkaline | Not listed |
| August Wi-Fi Smart Lock | 2 CR123 or CR123A lithium | Up to 3 months |
| Other August smart locks | 4 AA alkaline | Not listed |
| Level Lock | One CR2 lithium | Up to 1 year |
| Level Bolt | One CR2 lithium | Not listed |
From each maker’s support pages, tip sheets and product pages.
Alkaline or rechargeable?
Kwikset says rechargeable batteries won’t harm its locks but aren’t recommended, because their flatter discharge curve can make the battery percentage inaccurate. August doesn’t recommend rechargeables in the Wi-Fi Smart Lock either, because of their limited capacity.
If the batteries die
Yale says a YRD216 or YRD226 still opens with its mechanical backup key, and on a YRD256 you can touch a 9V battery to the terminals on the front of the lock. Google describes a similar 9V revive for the Nest × Yale Lock.