Player powered by an easily swappable 18650 battery?

The 18650 Lion battery has become a standard for LED flashlights. Why did this happen? The battery is very inexpensive, and holds plenty of power(up to 3,000 mah at 3.7 volts). 18650 batteries are bundled together to make batteries for notebook computers, and even to power cars. Since they are made in such huge numbers, the price is very low.

The 2,500 mah versions of the battery retail for under $5 each. A charger that charges one or two of these at a time outside the device in 3 hours is only around $10. While this battery isn’t tiny, it isn’t so large either. It holds the power of 3 AA rechargeables yet is less than double the volume of a AA battery. A shirt pocket sized mp3 player could probably be designed to be powered from an easily swappable 18650 battery.

The 3,000 18650 battery has 10x the power of the Clip+ battery. Imagine a player that runs for 120 hours on each of these, and lets you easily swap the battery for a charged one!