@Psl5065
The battery on the battery camera is not replaceable; in fact, there is no way to service the camera.
Perhaps you should contact Support to see if they'll replace the camera. We've had a battery camera since Sept. 2021, plugged in with the optional power cable, and it's online and "Live" all the time.
To contact Support:
1. Go to https://support.google.com/googlenest/gethelp.
2. Select a category/product family, and type in a brief description of the issue, then click "Next".
3. Click "Other", then click "Next step".
4. Under "Resources", just click "Next step". (Clicking one of the listed links will bring up a Help page page.)
5. Under "Contact options", choose to get a phone call or chat with the team, depending on availability in your country.
