Teardown of the Apple Watch Series 6 shows the 40mm model has an 8.5% bigger battery than the Series 5 and the 44mm model has a 3.5% larger battery
Context & Ripple Effects
iFixit has opened every Apple Watch generation since the 205mAh original in 2015, making its teardowns the standard record of how Apple spends internal space between watches. Last year it flagged that the Series 5's 40mm battery used a metal casing rather than a foil pouch, trading some capacity for physical strength and a more compact shape.
First-order effects
- The Series 6 ships with more capacity in both sizes — 8.5% on the 40mm and 3.5% on the 44mm — implying longer runtime at identical case sizes for day-one buyers.
- Repair shops get fresh parts data from iFixit's teardown, updating the battery reference they rely on for out-of-warranty Watch service.
Second-order effects
- The modest deltas suggest Apple is reclaiming space freed by the Series 5's compact metal-cased cell design rather than resizing hardware, keeping the form factor fixed while capacity creeps up.
- Rival smartwatch makers now benchmark against a Watch whose battery grows every year inside the same footprint, raising the bar for their own capacity-per-volume claims.
Third-order effects
- Across the teardown record — from the original Watch through the Series 3's 1.03-to-1.07 watt-hour bump to today — the pattern holds: wearable batteries gain single-digit percentages per generation because wrist volume caps cell size, pushing progress toward chemistry, packing density, and silicon efficiency instead.
- If that ceiling persists, battery life differentiation between smartwatch tiers will increasingly be won in power management rather than bigger cells.
The trend: Smartwatch battery capacity is inching upward within locked form factors, with each generation's teardown showing single-digit gains squeezed from cell design rather than size.