The 80% Limit
Lithium-ion batteries degrade faster when they are held at exactly 100% capacity for extended periods. To combat this, Apple includes a feature called “Optimized Battery Charging” on the Apple Watch. By default, if you charge your watch overnight, the software will rapidly charge the battery to 80% and then intentionally freeze the charging process. It uses machine learning to guess when you usually wake up, and attempts to trickle-charge the final 20% right before you take it off the puck. However, if your schedule is unpredictable, you will frequently pull your watch off the charger only to find it is stuck at 80%, leaving you without enough power for the day. You must disable the artificial limit.
How to Turn Off Optimized Battery Charging
You can force the watch to charge to maximum capacity immediately via the Battery settings.
- Open the Settings app directly on your Apple Watch (the grey gear icon).
- Scroll down the main list and tap on Battery.
- Tap on Battery Health.
- Scroll down and locate the toggle switch labeled Optimized Battery Charging.
- Toggle this switch to the Off position.
- A prompt will ask for confirmation. Choose Turn Off (or “Turn Off Until Tomorrow”).
Maximum Power
The change is instantaneous. The Apple Watch will completely bypass the machine learning algorithm. The moment you place the watch on its magnetic charging puck, it will draw maximum current until the battery hits exactly 100%, and it will hold it there. While this may slightly increase battery degradation over several years, it guarantees that you will always wake up to a fully charged watch, regardless of your schedule.