GoKawiilWhile eliminating e-waste and extending the life of tech products is great, there comes a time when an Apple Watch isn't worth bringing back to life with a new battery. First, consider software support. The latest watchOS 27 drops support for many older devices; it's only available for the Apple Watch Series 9, SE 3, and Ultra 2 and newer. That means if you own an Apple Watch Series 8 or older model, you won't get the latest software update. Your watch will continue to work just fine, though.
In fact, many people report still using models as old as the Series 4 today. The previous generation watchOS 26 had wider compatibility, working with models dating back to the Apple Watch Series 6 and second-generation SE. This means the Apple Watch Series 5 and first-generation SE (and older) are no longer supported, with their software end of life dating back to September 2024.
Your iPhone model shouldn't be a concern Apple's iPhone and Apple Watch compatibility page shows that older watchOS versions work fine with modern iOS releases, though you can't use the latest Apple Watch with an iPhone running an old iOS release. For example, an Apple Watch Series 11 (our review) will only pair with an iPhone 11 or newer that's running iOS 26 or later.
Apple Watches don't hold their value for as long as many other Apple products, so you may not recoup the battery investment if you resell the watch. Check what comparable models are selling for first so you know how much profit you could make. If you're handing the watch down to a friend or family member, consider giving it a replacement battery so they can enjoy the wearable for years to come.
To help you decide what's best, consider the age of the watch, software support, cost of the battery, and how much longer the watch will likely be supported. I'd suggest replacing the battery for a Series 6 or 7 and above, which are the oldest models compatible with watchOS 26. But for anything older than five or so years, you're better off upgrading instead.