How long can I wear the watch on a fully charged battery?

The Philips health watch has a built-in rechargeable battery. When the battery is empty, it can be fully charged in approximately 90 minutes. With a fully charged battery, the device can be used for approximately 4 days until a recharge is needed. When the battery is almost empty and requires charging, the low battery icon will appear on the home screen. When the battery is empty, the display turns off and no further data will be stored.