> And you'll notice that AA batteries are almost universally ... gone; replaced with built-in batteries or custom-wrapped lithium batteries. Ever open up a Dew

> And you'll notice that AA batteries are almost universally ... gone; replaced with built-in batteries or custom-wrapped lithium batteries. Ever open up a Dewalt battery pack? It's a circuit board and a whole bunch of 18650's. All of them are 3.7 V. What's different is the amount of power they supply and the energy they hold, how fast they can recharged, etc. But we have that with the AA/A/C/D standard as well. Some batteries can hold more energy, some can deliver more current for a longer time, etc. NiCad, Alkaline, NiMh... etc.