Apple Watch is best to use the original charger to charge and avoid overcharging.
The original charger can ensure the stability of voltage and current, avoid abnormal situations such as overcurrent or insufficient voltage, and protect the health of the battery.
Overcharging will affect the battery life, resulting in battery heating, polarization, etc., so the charger should be unplugged in time to avoid overcharging.
iwatch How to charge good battery?