The Apple Watch is a powerful health and fitness tracking device but Apple's advanced features have no value if the battery dies. That's why Apple Watch charging issues need to be taken care of immediately. On a full charge, an Apple Watch should last throughout the day in normal use and with the latest Apple Watch Series 7 a quick top-up can add enough to go all night as well.
The Apple Watch has always been described as lasting all day. In recent years, Apple has elaborated on that general statement with an exact number, specifying up to 18 hours of use. Naturally, each person will get different results since it depends upon which features are used, screen brightness, and whether the Apple Watch has and uses cellular capability. There are ways to extend battery life but ultimately charging is a necessity.
There might be times when an Apple Watch is placed on the charger and it simply doesn't charge, which can be very frustrating if this detail is missed. When the magnetic click to the Apple's charging puck happens, the Apple Watch's screen should change to briefly show a green lightning bolt icon, then, if Nightstand mode is enabled, the display changes to a helpful clock view. If the charging icon is not seen, something is wrong and the first thing to check is that the Apple Watch is attached correctly. The magnet should provide perfect alignment but if something is caught between, it could be angled or blocked from working. The next step is to make sure the other end of the cable is plugged into a charger. Since wall adapters are now meant to be shared between devices, charging an iPhone might mean unplugging the Apple Watch.
Apple Watch Charging Solutions
Being plugged into power seems like an obvious thing to miss but it happens to everyone. If the Apple Watch charging cable is plugged in and attached securely to the device but still doesn't charge, it could be an issue with the cord itself and an examination might reveal damage that would require a replacement. Another possibility is that a power strip or surge suppressor is switched off or needs to be reset after a spike in power. Switches on the power supply might help activate the plug and restore power to the charger and the Apple Watch.
There is a software reason for an Apple Watch not charging completely and the pause in charging when almost full is on purpose. Optimized charging means the Apple Watch learns the user's routine and charges until it reaches 80-percent, then waits to make the final push to reach its full capacity exactly when the user is anticipated to start using it again. If none of the solutions above worked, a reset of the Apple Watch could help. Pressing and holding the side button and Digital Crown until the Apple logo is seen will reset the Apple Watch and could clear up any software problem that prevented charging.
Source: Apple