An improved prosthetic device with a vacuum system for maintaining a negative pressure seal between the socket and the residual limb. The vacuum system includes a vacuum surge chamber which maintains seal vacuum and increases the time between recharging a Li ion battery, allowing the battery to be recharged-up to 500 times. The system is small, lightweight, and concealable within the prosthetic device so that it neither impedes use of the device nor detracts from a cosmetically accurate limb.
