Backpack based system for human electricity generation and use when off the electric grid

An electricity-generating backpack that is substantially lighter in weight, has the multiple springs replaced with one large spring whose spring constant can be adjusted in the field in seconds, and replaces a DC generator with a brushless AC generator that permits approximately 70% generator efficiency and the generation of up to 20 W of electrical power by converting mechanical energy to electrical power. A device is provided that always removes some electricity, but not too much, as necessary to extract large levels of the electricity while controlling damping by providing electrical damping circuits including a DC-DC converter designed to emulate a desired load at its input terminals. Additional electricity generating E-MOD devices may be used for generating additional power by hooking an E-Mod device to a generator and to the backpack belt at the wearer's hip and includes a wand that fits against the wearer's femur so as to move through a range of motion as the patient walks. The system also provides multiple possibilities of electricity generation when not walking including a light-weight bicycle ergometer which can be mounted to the backpack frame and generate very high power levels (100 W). The electricity generated and stored by the backpack may be used to charge batteries and to power a number of devices that may be carried by the backpack, such as a Sterling Cooler System that is powered by the backpack's stored power to provide cooling power for cooling items carried by the backpack.