Yeah - mAh is to do with the total amount of power in the battery. So, for instance, of a 1000mAh, you can draw 100mA for 10 Hours. Although, usually, with Alkalines especially, this is not the case, as the capacity of the battery is highly dependent on the level of current draw. At low currents, they achieve about 2000mAh, but when you crank up the juice, they drop as low as 600 or 700 pretty quickly.
The advantage of NiMh batteries is that they cope with high loads very well. If a battery is rated for 2000mAh, you can pretty much expect this across the board for current draw. In addition to this, as Alkaline batteries run, the voltage slowly declines, this is not the case with NiMh, achieving 1.2V consistently until just before they go completely flat (good servo performance for the whole life), which is why I switched to them.
What I am not so clear on, and seems a little bit odd, is that if I have 5*2500mAh AA's in my pack, does that make a total of 12500mAh?? Because that seems like a HUGE jump from 1000. Mind you, I have been running these babies without charge for about 10 hours or so now, with no degradation in performance, so maybe that is the case.
