DT. No. 1 F3 Smartwatch review – powered by Button Cell Battery By Gogi Rana on September 18, 2017 12 Comments The DT. No. 1 F3 Smartwatch is one such smartwatch that gets power from a button cell battery. This a simple digital watch, with same features as seen on a digital watch but it comes with built in Bluetooth and fitness tracking and alert features.