It has often been said that patience is a virtue. Patience can also be profitable. For the last 10 years or so, ZPower–a battery technology company in California–has been been busy toiling away on a silver-zinc rechargeable technology that aims to replace the lithium-ion battery technology that is so ubiquitous of late in portable products:”ZPower’s efforts are based on existing silver zinc technology, offering greater power density (essentially, how much electricity a battery can hold) than lithium ion, thus