Czech hacker Josef Pr??a took a look at his useless three-cell MSI Wind battery and wondered why it didn’t have a USB socket in the side. Surely it could power smaller, less thirsty devices than a netbook ? After popping the case with a knife, he discovered that there was actually plenty of room left inside. Enough room, in fact, for a USB port and a voltage regulator.

It turns out that there is enough power in the 12 volt battery charge an iPhone twice, although of course you can use it with any USB-powered device. It also turns out that the power conversion, stepping down from 12 volts to 5 volts, generates a lot of heat, so Josef upgraded his passive-cooling device (a heatsink) to a bigger one, bringing the temperature down from a toasty 120?C to a more manageable 70?C, and punched through the stickers covering some existing holes in battery case for better air flow.

It looks like a simple hack, and damn useful too. As my wonderful and generous editor Dylan Tweney mentioned, it would be better if it worked with the battery still in the laptop, but still, I’m going to give it a try with my own spare Wind battery.

USB iPhone battery pack from MSI Wind battery [Prusadjs. Thanks, Josef!]