Pretty much the only new feature in the Series 5 Apple Watch is the “always on” feature, where the watch’s display is always on in a dimmed, slow-refresh state. Apple says that this doesn’t affect battery life very much, but anecdotal evidence has suggested that this is not the case.
I did my own testing a couple of days ago, and found that the battery life was well below what the Series 4 offered, but still, in my limited usage, within the 18-hour range that Apple claims.
However, my usage was limited. Here’s what Apple says about how they measure battery life on the Apple Watch:
All-day battery life is based on 18 hours with the following use: 90 time checks, 90 notifications, 45 minutes of app use, and a 60-minute workout with music playback from Apple Watch via Bluetooth, over the course of 18 hours. Apple Watch Series 5 (GPS) usage includes connection to iPhone via Bluetooth during the entire 18-hour test. Apple Watch Series 5 (GPS + Cellular) usage includes a total of 4 hours of 4G LTE connection and 14 hours of connection to iPhone via Bluetooth over the course of 18 hours. Testing conducted by Apple in August 2019 using pre-production Apple Watch Series 5 (GPS) and Apple Watch Series 5 (GPS + Cellular), each paired with an iPhone; all devices tested with pre-release software. Battery life varies by use, configuration, mobile network, signal strength and many other factors; actual results will vary.
I did not do any workout or listen to music, nor did I have any 4G connectivity; I was home all day. With 43% left on my battery after about 13 hours, I find it hard to see how, in the above conditions, the watch would make it to 18 hours.
Yesterday, I did another test, this time with the always on feature disabled. While in my first test I took readings at more or less random times, I tried to be more regular in the second test. Here are the results in chart form:
With always on enabled, my watch was at 26% after about 24 hours. With it disabled, it was at 46% after the same amount of time. (Note that I slept with the watch on for both test, with the watch in theater mode, and with do not disturb enabled.) But, again, there was no workout, no music playback, no 4G connectivity. This strongly suggests that Apple is over-estimating battery life on the Series 5 Apple Watch, but also that the always on feature does hit the battery considerably. In fact, after about six hours, there’s a 20% difference in total battery power, which, interestingly, remains pretty much stable for the rest of the test.
Now I work at home, so there’s no way that I would deplete my battery given the way I use the watch, but if you are out and about, doing workouts, playing music, and connected to 4G, you really need to be careful. I think the always on feature is very good, and if you’re aware of how much it hits the battery, then you may want to use it. But if you plan to not be near a charger until the end of the, and you’re using other battery intensive features, you might want to turn it off.
If I have time next week, I’ll try some more testing: with a workout, music playback, and 4G connection, starting when I get up in the morning, and see how quickly the battery depletes.