I am currently using a 3.7V 100mAh lithium ion battery. So far I have run two tests: 100% brightness (too bright to view) and 5% brightness (my optimal viewing preference).

100% brightness - 2hr 22mins
5% brightness - 5hr 45mins

This is without any bluetooth or further battery optimizations. I am also looking into upgrading to a 500mAh battery as there is still plenty of room left to add a bigger battery.

You do have to disconnect to recharge, however the batteries are very cheap ($2-7) and can be swapped while the other is charging.

• I have taken apart an RFID chip and found it would fit perfectly in the center of the watch or even on the watch band. However I damaged the outer induction coil so was not able to further test.
• I am switching the companion app to use rxJava for BLE which will make implementing future features faster and easier.
• I am working on a custom 'virtual' watch in the app so you can preview features before you apply them to the watch