A milliAmp hour, also known as mAh, is a barometer to explain how much current a battery will discharge over a period of one hour. Higher numbers reflect a long battery runtime and, typically, a higher storage capacity. For example, a 2000 mAh pack will sustain a 2000 milliAmp (2 amp) draw for one hour and a 1700 mAh pack will sustain a 1700 mAh (1.7 amp) draw for the same hour, etc.