The 40mm Apple Watch Series 5 comes with a new battery design – Engadget

Apple’s latest smartwatch model isn’t that different from Series 4, but its 40mm version is apparently hiding a component that’s dramatically different from its peers. iFixit has discovered that the smaller Series 5 watch uses a battery encased in metal instead of in black foil pouch like typical lithium-ion batteries. Its larger 44mm sibling is powered by one of those standard batteries. The teardown website found a patent that could explain the change: the new metal casing is apparently more space efficient and can free up valuable real estate for a small device.