Chemistry determines the cell voltage (1.2V or 1.5V and there are others like Lithium at 3.0V), whether the battery is rechargeable, and how the voltage changes as the battery discharges i.e. at what voltage is the battery considered to be flat or fully charged. Switched mode power supplies. One more point.
The Average Bike Riding Speed. The average road bike speed is between 11 and 12 mph. Bike riding speeds vary widely depending on your riding conditions. When you are zooming down a paved hill, your speed may increase to over 20 mph, while you may slow to only a few miles per hour when you are climbing a steep or rocky grade.
Day 2: Sunday (long ride, 80% of race pace) This was a tempo ride covering 104 miles (167 km) with 5,600 feet of climbing. Average pace was 17 mph (about 28 km/hr) with lots of headwind. My average HR over this 6 hour ride was 141 and average power output was between 190 and 200 watts.