Chances are you are using the wrong cable to charge your devices, and maybe even the wrong cable to transfer data to your computer from an external drive. This video explains in laborious detail all about USB cables and why some transfer data slowly and some charge slowly. If you want the best of both worlds, skip to time 14:20 where the CableMatters 80GB/240W cable offers a clear solution to both speed and power. But, please, watch the entire video to fully understand the complex world of USB specs - if you can.