Earlier this week, iFixit completed the disassembly of the Apple Watch Series 4, saying that the 44mm version of the battery capacity increased by about 4%, but that is compared to the 38mm version of the Apple Watch Series 3.
According to Apple's documentation, the battery capacity of the Apple Watch Series 4 is actually smaller than the battery capacity of the Apple Watch Series 4:Apple Watch Series 3 (42 mm): 1.34 watt hoursApple Watch Series 4 (44 mm): 1.12 watt hoursApple Watch Series 3 (38 mm): 1.07 watt-hours
Apple Watch Series 4 (40 mm): 0.86 watt-hours
More specifically, the Apple Watch Series 4's 44mm version has a battery capacity that is approximately 16.5% less than the 42mm version of the Apple Watch Series 3. Similarly, the 40mm version has a battery capacity that is approximately 19.7% less than the 38mm version. Despite the smaller battery size of the Apple Watch Series 4, Apple said at the press conference that, like the Apple Watch Series 3, the new Apple Watch has a battery life of up to 18 hours.
What we know is that the Apple Watch Series 4 uses a new display technology called LTPO to improve power efficiency. The new Apple S4 chips also have more efficient cores, so they may consume less energy and other components may be more efficient.
However, the battery life of a device is often difficult to predict. Different users have different usage habits, such as athletes who regularly use Apple Watch and casual users who occasionally open watches to view notifications. In short, we want to clarify some of the confusion surrounding the Apple Watch Series 4 battery. Although they have less battery capacity, they do not seem to affect the battery life. Currently, Apple has not commented on this matter.