No adhesive for its protective sleeve, but this battery is certainly securely soldered.

It provides 1.85 Wh (500 mAh @ 3.7 V) which ought to re-juice those twin 0.1 Wh earbud batteries a handful of times.

The rest of the cables are similarly soldered, we also spot a simple hall effect sensor up top to track the lid state (open/closed).

This charging case seems to have enough room for no-fuss ribbon cables and power connectors, without much risk of disconnection. Fairphone may have fair reasons, but repairs—and device life—will certainly suffer without these aids.