Subject: AA alkaline battery discharge curve

Hello!  I am an electrical engineering student and am currently 
co-oping.  At work, I have been given the arduous task of 
approximating the runtime of a certain digital device that runs on 4 
AA alkaline batteries (in series).  Since the *expected* runtime is 
close to 2000 hours (and the device turns off after 45 minutes if no 
buttons are pressed), this is obviously going to take a LONG time to 
test.  I have been looking for information, specifically a "magic 
equation", that will be able to tell me about how long this thing will 
last (note that the device will not function if the voltage drops 
below 4.24V).  Here is all the pertinent information that I have:

Cutoff voltage: 4.23V (or 1.0575V/battery)
Average current draw: .71mA
Alkaline Batt. capacity: 2450mA-h
Avg. power drain (V*I): 3mW

If you can tell me how I can go about solving this or even lead me in 
the right direction, I would be greatly appreciative.  Thanks a lot!

mike cloppert

Re: AA alkaline battery discharge curve