The Apple Watch Ultra has a 76 percent larger battery capacity than the 45mm Series 8, according to newly discovered specifications in China’s certification database. The certification, found by MySmartPrice, shows that the Apple Watch Ultra has a battery capacity of 542 mAh. The 45mm Apple Watch Series 8 has a battery capacity of 308 mAh, which is a 76 percent increase in battery capacity compared to the previous largest Apple Watch .
The documents also confirm that in addition to the Apple Watch Series 8 having the same CPU as the Series 6 and Series 7, the new Apple Watch also has the same battery capacity. 41mm Series 8 has a 282mAh battery, while the Series 7 has the same 284mAh battery. The minimal difference in battery size is unlikely to be noticed. The 45mm Series 8 also shares the same battery size as the 45mm Series 7.
For the Apple Watch Series 8, Apple promises the same all-day battery life as previous generations of the model. For the Apple Watch Ultra, Apple says users can expect up to 36 hours of normal use and up to 60 hours with low-power mode enabled, meaning it alone can provide the longest battery life since the Apple Watch line was released.
Low Power Mode is available for all Apple Watch models supported by watchOS 9 and extends battery life by disabling background app refresh, always-on display, background blood oxygen measurement and more.