Abstract: An on demand power device which allows users to selectively choose the desired voltage/current/power and/or amp-hour (A/H) capacity output from among a range of output available within the power device. This device relates to batteries used as long-term stand-by or back-up power sources such as for emergency use with a motor vehicle, during camping, vehicle starting/towing, and for power consumer electronics such as mobile phones or a global positioning systems. This device also relates to batteries for usages on water, underwater, on land, under land, in the air or in space which require power at discrete intervals.