Suggestion: Mobile charger accepts redstone [Not Approved]

Bat pack works well for that, it's 6 batteries in one, and with two of those, you can pretty much fill inventory with full ores and any other goodies, but good idea

I remember reading in one of the IC tutorials that you could use redstone to power a machne or device, but it didn't provide much power.

TreeFarmer is right though, I crafted two Bat-Packs that I take with me and I always run out of inventory space before I run out of power. Having a solar panel setup with a couple of MFE's will give you a renewable resource for charging packs instead of using your redstone. Just remember if you're in a snow biome to clear the snow off the solar panels or they'll stop working!