Apple Watch battery life lasts

The battery is probably on the way out in such an old watch,visit an apple store to have your battery checked out,if it's battery health figure is 80% or near then it is recommended to replace the battery($79).

Hello!

It will have up to 18 hours of battery life!

"Apple Watch All-Day Battery Life testing was conducted by Apple in August 2021 using preproduction Apple Watch Series 7 (GPS) and Apple Watch Series 7 (GPS + Cellular), each paired with an iPhone; all devices were tested with prerelease software. Battery life varies by use, cellular coverage, configuration, and many other factors; actual results will vary. See apple.com/batteries and apple.com/watch/battery.html for more information."

You can read this support page to learn how to get the most out of your battery on all of your Apple devices (including Apple Watch): Batteries - Maximizing Performance - Apple!

I hope this answers your question!

Please read the support page above on how to maximize and get more out of your battery! It will show you how to increase that battery life more!