[E-Revonut]

AA alkaline batteries are 1.5V/cell versus Nixx at 1.2V/cell. I would guess the radio can prolly handle at least 6.5V. I took mine apart to see how much room is in there, there is actually alot of room! I ran 2500mah Energizer nimh for awhile but after about an hour I can notice a drop in range and the voltage is down to 4.8V. For the fall carpet season at my lhs I ran Duracell ProCell batteries and got a season and a half out of them plus all the bashing I do, I won't bother with rechargeables anymore, $5 worth of Duracells last me about 6 months, have a higher voltage and better range.