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.
On my reasonably flat commute I average around 16 mph on my road bike, but your average speed is dependent on many different factors. A general rule of thumb is that if you are switching from a mountain bike with knobbies to a road bike you will be between 15-20% faster at the same watts/effort.