How old is your One? I'm wondering if it's just starting to reach its end of life.
Fitbit offer these tips to maximise the battery life of the One:
- If you use the Fitbit app, make sure All-Day Sync is turned off. All-Day Sync increases battery drain on both your tracker and mobile device. To find the setting, open the app and tap or click the Account icon (
). At the top of the screen tap or click One to see your settings, then scroll down. - (Android only) Turn off the Always Connected setting. Similar to All-Day Sync, it can reduce battery life.
- If you have many silent alarms set, consider deleting some. Each alarm you add up to the maximum of 8 reduces battery life by a small percentage.
- Don't charge your tracker in extreme heat or cold. For best practices, see How do I charge my tracker?
taken from: https://help.fitbit.com/articles/en_US/Help_article/2004/