HOW TO SAVE BATTERY LIFE OF APPLE WATCH?

Batteries - Apple is a link explaining how Lithium ion batteries work. Follow that link for best practices on keeping the battery on your watch as well as all Apple products up to snuff. Most batteries last 2-5 years as long as they aren't left in the sun, in the heat of sun beating into a car with closed windows, or near heating vents in a house. And you don't want to freeze them either or expose them to water or liquid.