“Over the years, users of portable consumer electronics have just come to accept that battery life gets worse over time. But it doesn’t have to: Gbatteries, which is in the current batch of Y Combinator companies, has come up with a new technology called BatteryOS that provides better performance without battery-life degradation.
The first example of this technology is BatteryBox, a rechargeable Lithium-ion battery pack that carries enough power — 50 Whr — to run a MacBook Air for 12 hours, a MacBook Pro for six hours, or to charge eight iPhones.”