Welcome, Ed!
mAh is used to let you know how much "power" a battery provides. In our automobiles, it is Amp-hours.
There are a lot of 600 mAh batteries. That means it provides 600/1000 of an amp for 1 hour. If we do the math that is .6 amps for 1hour. 6 amps for 1/10 hour or 6 minutes. 3 amps for 1/5 hour or 12 minutes. Now that is all theory, and batteries do not put out the top voltage for the full 12 minutes, so the amps increase as voltage drops and the battery dies more quickly. The numbers help you to know about how long the battery pack will last in a certain applied situation, and how fast you should re-charge that battery pack. This has been an education to me too. [img]i/expressions/face-icon-small-wink.gif[/img]