Anyone shooting HD video on a DSLR knows how quickly the battery can drain. You can get AC power adapters for some cameras, but where there’s video, there’s not always an outlet. 

In this tutorial (see above video), camera hacker Chris Winter shows you how to make an external battery pack system with about nine times the runtime using a $40 battery pack, DC coupler, hot-shoe plate and some Velcro.

If you don’t want to watch the whole video you can figure out the setup by visiting Winter’s blog where he lists all the necessary parts (with links to purchase) for the Canon EOS 5D, 7D, 70D or the T4i, T3i and T2i.