Apple Watch Ultra – the truth behind the battery claims

For endurance athletes, the real claimed battery life of the Apple Watch Ultra is a mere 12 hours. So its star athlete from the announcement video, the ultra runner Ray Zahab, simply couldn’t use a Watch Ultra for his events like the 6-day Marathon des Sables over 156 miles without a nightly recharge.

Q: What? I thought Apple said it was 36 or 60 or whatever. But not 12.

A: Nope. Apple definitely says in the specs that Apple Watch Ultra gives “Up to 12 hours outdoor workout with GPS”. And it gets worse as that figure is reduced to 10 hours with LTE.

It gets worse still.

Apple’s tests used a separate Bluetooth heart rate monitor, which is interesting as it finally lays to bed the conundrum of whether maintaining a BLE 5.3 connection was more efficient than using the internal oHRM. Now we know. That’s by the bye, the point is that if you don’t use a chest strap, the GPS battery life will definitely be less than 12 hours.

Then it gets even worse. Or maybe better. I’m not sure which. Here’s why.

Apple increases GPS accuracy with dual-frequency reception. That definitely uses more battery juice, conservatively at least 10%. Yet when Watch Ultra was launched in the keynote presentation, it was specifically stated that most people could complete an Ironman with full precision GPS. Here’s an extract from the transcript:

For endurance athletes, the bigger battery makes a big difference. Of course, you can easily complete a marathon with battery life to spare. Using the new low-power workout setting, most athletes can do a 2.4-mile swim, plus a 112-mile bike ride, and then run a marathon to complete a long-distance triathlon with *full precision GPS* and heart rate.

First up the average Ironman completion time is  12:35:00. So for Apple’s claim to be accurate, it needs to be based on a battery life of at least 12:35:00.

So let’s say that Apple has equated that time to its low-power, high-precision mode. ie by turning off the screen and using a chest strap. If instead, the Apple Ultra owner used the lower quality reception, battery life would increase to, say, 14 hours but that’s still in low power mode without an always-on screen.

Against all of that, I’d point out that earlier Apple Watch models could get similar GPS battery lives provided that the display was mostly inactive, so there is some hope of better performances in some circumstances with a new battery or by fiddling around with various power-saving settings.

So, I’m a little bit unclear as to what the battery life is with and without dual frequency or if the low-power mode needs to be used to get 12 hours of GPS time.. Further, Apple seems to be slightly ‘toying’ with its various claims for example whether or not a Bluetooth chest strap is used.

Thoughts?

I’ll finish with Apple’s precise battery claims based on specific use cases. This is a good way to justify their claims and Garmin does a similar thing albeit more focused on sports usage. The real truth will come in two weeks’ time when we have the watches to test.