Apple Watch SE (2nd generation) battery drains too quickly

The Apple Watch SE (2nd generation) is rated for about 18 hours, which means it is designed to be charged every day, so a watch that needs charging each evening is behaving normally. Apple's page on a battery that drains too quickly points to settings and to the battery's condition. The settings with the biggest effect are Always On, a bright display, Background App Refresh, and cellular use on the cellular model, which drains more than Bluetooth to the iPhone. Workouts with GPS draw heavily, and Low Power Mode, which turns off some features and reduces others, extends the day and switches off itself when you charge above 80 percent.

If a watch that used to last the day now dies by afternoon, check Settings, Battery, Battery Health, where the watch shows maximum capacity; a figure well below 80 percent means a battery service is due. After updating watchOS or restoring the watch, battery life can fall for a few days while the watch re-indexes, so judge the battery after about a week. Raise-to-wake and the screen's brightness also add drain, and the SE 2 can use Always On Display less than Series models because it does not have it.