HyperMac is an external battery pack for all Apple laptops. It's available in four capacities, ranging from 60Wh to the most powerful 222Wh, which we tested here.

For comparison, the MacBook Air's battery is 37Wh. The device comes supplied with MagSafe cables for connecting to a MacBook, MacBook Pro or MacBook Air, and offers a USB port so you can also use it to run your iPod, iPhone or other USB powered device.

HyperMac charges your internal battery as well as powering your notebook, and is expected to last around 1,000 charges before wearing out. We tested the 222Wh model with a regular 13-inch MacBook.

According to the Battery Life Chart, it should last four times as long as this MacBook's internal battery, or 25 hours of web-surfing and document-editing with the screen brightness set to 50% and the power setting on Better Battery Life.

In our slightly more demanding tests, with a much brighter screen, the power setting on Normal and performing activities that make the hard drive spin, we got nine hours 50 minutes, which is far from shabby. And, we could have squeezed out a more hours using 'Better Battery Life'.

Our only criticism is the version we tested is the size of a large paperback and almost as heavy as the MacBook we tested it on. Do invest in a HyperMac, but when choosing which model to buy, bear in mind the trade-off between capacity and bulk.

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