Protonex, based in Massachusetts, USA designed and built portable power solutions for remote and mobile applications in the 100 to 1,000-watt power range for the commercial and defence markets addressing the power needs for a broad spectrum of applications such as field battery chargers, auxiliary power units (APUs) for silent watch, unmanned aerial vehicles, digital communication systems and intelligence gathering sensors. Protonex was sold to Ballard Power Systems in an acquisition by share swap in 2015.