The Apple Watch Series 3 has pretty weak battery life if you rely on it for placing phone calls.
That's one of the highlights of Apple's new watch — the ability to place and receive phone calls even if you leave your iPhone at home — but doing so will drain your battery at a rapid pace.
That's not enough for you to actually go about your day without your phone, especially if you're planning to take a few conference calls. Things get a bit better if you have your phone nearby; in that case, you'll get about three hours of phone calls.
Apple says the Apple Watch Series 3 should offer about 18 hours of battery life for mixed usage. Sounds like it'll be a good option for phone calls if you need to run out to the store, but not enough to leave your iPhone at home all day.