[iamevn]

Pebble smart watches are tethered (to an android/ios device via bluetooth), do not talk to a cellular network, and have had an especially good battery life because of that and their low-power displays which are always on and visible with external light, only turning on the backlight when you are using it (e.g. hitting buttons or after giving the watch a little shake). afaik, every Pebble watch has had a significantly longer battery life than all of Apple's watches even though they're always displaying.

The newer Pebbles do have a better battery life, lasting multiple weeks maybe thanks of better battery tech.

[comfydragon]

I think most of the battery life improvement is the much more power-efficient SOCs available. The original Pebble used an STM32 processor and a TI Bluetooth chip, where nowadays having BLE integrated into the SOC is table stakes.