You can find mAH ratings for AA batteries online. Last I looked they were like 1200 or 1500mAH for Alakaline batteries. 2 in series woulfd be 3V @ 1200-1500mAH.I have a 1000mAH LiPO built into an RF remote. It has measured 4.1V when fully charged. It is pretty darn light.I use a MAX1811 chip to control charging it from a 5V source.I don't know what the wiimote have for voltage control. We use 2 AAs in ours, or 2 NiMH batteries - I think the base they plug into takes care of charging them.Haven't tried opening one to see what's in it.
Yeah I'm the same way, never got into the 'wii' idea of gaming. I feel better about touch based interfaces (iOS) as it's somewhat tactile, but a nice joystick is hard to beat.
And take a look here!http://batteries.batterymart.com/search/indexmore battery types than I even knew existed!Saw some that are listed as 45V even - that'll get that wiimote rumbling in your hands!