I see things like 18650, 16340, 123, 123A, 14500 and 10440, 3.7volt, 2200mAh. What does the 18650 represent? What does 3.7v do vs. 6v? 2300, 2600, 2900mAh affects what? Is there a great post with info on the different tyes, sizes and power of batteries here in the ECF? Or maybe a good...