Apple Watch Series 5 40mm: new battery design, 10% additional capacity

A dismantling of the 44mm Apple Watch Series 5 made by the iFixit repair site revealed few design changes compared to the 44mm Apple Watch Series 4, but subsequent disassembly of the model 40 mm revealed larger design gaps.

The battery inside the Apple Watch The 5 Series has a new metal case, probably made of aluminum, rather than the aluminum bag that surrounds most lithium-ion batteries.

Based on an Apple patent, iFixit suggests that the new metal case is designed to be a more effective method for sealing batteries. The size of the Series 5 battery compartment does not seem to have changed much compared to the Series 4 model, but the Series 5 battery offers 10% more capacity than Series 4 (0.944 Wh vs. 0.858 Wh).

Aluminum pouches have a wider seal than the metal case. So, with the design change, Apple was able to use the space saved for a slightly larger battery.

New battery design on the left, old design on the right

iFixit indicates that the metal case also makes the battery physically stronger, which is ideal for repair. An aluminum housing makes punching more difficult during repairs.

The new design is limited to 40mm Apple Watch Series 5 and has not been seen in the 44mm Series 5 model. IFixit explains that it's not clear why the updated design was used in a watch and not in it. another, but it might be that the smaller watch needs an extra battery or that Apple wants a "discrete" method to test the design.