Latest data point: during travel yesterday I used the MB Air away from an electric plug, but with this battery extender, for ten straight hours and was nowhere close to using up the power. Details after the jump, but my experience is: for a price, this is a way to eliminate all questions about whether you can get enough working time out of the MBA.
- When you attach the QuickerTek device to the MBA, it serves as an external power source. Drain from the internal battery appears to stop as long as there's any juice to take from the external source. The internal battery meter on my MBA read 99% when I powered it up at the beginning of this process, and it still read 99% eight and a half hours later, at which point it started to tick down.
- at 10 hours, the internal meter read 58% power left. So the practical limit was me wearing out, not the battery.
- I was applying mild but not draconian power conservation measures through this process. Had "better battery life" selected from the power options (rather than "normal" or "best performance") and had the screen slightly dimmed. Was not on the internet and had the Airport turned off. But I was typing up a storm.
- The external battery is lighter than it looks -- weighs just over one pound. Of course it's messier to have it sitting next to the machine while you work, rather than being internal.
- Spec sheet says it takes 3 hours to recharge the external battery fully. The four or five times I've done so, it's been more like 2 - 2.5 hours. It's working off 240V power here in China, which conceivably could make a difference. A red light turns on while it's charging and switches off when it's full.
- You also have to buy a special cord to connect this to the computer. Details on the site.