You know the situation. You are stuck somewhere in the boondocks with no power and no way to recharge your gizmos. What can you do? If you have an extra battery for your netbook lying around, then you can mod it to create your own USB power pack to power up all those thirsty USB gadgets.
Some of us have some spare netbook batteries lying around. For example, if you upgrade to a larger capacity battery, it's possible that you won't use your older one anymore. Or if you change netbooks. Anyway, there are probably a bunch of netbook batteries around that no one uses. This DIY will get some use out of it. This build requires you to work with the battery itself and do some soldering, so if this isn't your cup of tea, then you should not do it. And before you think that you are ruining the battery of your netbook, think again! The battery can still be used in the netbook, so this is a sweet little mod. Another good reason to try this is that the power packs that are available are quite expensive. Sure they look good and are handy, but what if you could create your own with some stuff that you already have?
Josef Prusa managed to use an old MSI Wind battery to make it into a power pack for USB devices, like his iPhone. The first thing he did was to open it up. It's harder than it looks and he had to use a knife. He first had to find the right space to cut the holes for the connectors. A three-pin connector is the 12V supply, so there is no way to plug it wrong. Once he found the source, he soldered cables onto it. A USB needs 5V and this is regulated by a 7805 from the 12V, which can get pretty hot so it needs some cooling. The comments on his post suggest using a switch mode 7805 drop in replacement instead. It will give you 85% power utilization instead of the 40% that this build gets. You can get one here.
He cut a few holes in the case for cooling and closed the case. The job was done. It's a cool hack and it's pretty effective. He tested it on his iPhone, which was charged in 2 hours and 22 minutes. You can charge your iPhone two times with the battery, then it needs to be recharged. If you've used the switch, then you can probably get even better recharge time. By our account, it means that one netbook battery should charge an iPhone 3 or 4 times before it needs to be recharged itself. That's pretty handy!
MORE POWER PACKS
Mophie Juice Pack