I spent the whole night taking pictures....a lot using alkaline batteries to see the when the camera will shut down, so I got some numbers that might help users with the A720IS (don't know if this is also valid for other cameras...)
Max:New Alkaline Duracell Plus: 2928v
Fully recharged 2500mAH batteries: between 2700v and 2663v
Min:Alkaline batteries that came with the camera the minimum voltage is 2150v until shutting down.
I haven't tried with the rechargeable batteries yet, but as soon as I can, I will let you know
