well in a nug shell, those tiny comp fans have 2 wires, negative and positive. First you have to make sure that the charger voltage will support the fan in the first place. If it does [look at voltage on the charger and the fan, usually says it on it] then touch the positive to the positive on the battery and the negative to the negative and it should work. I didnt try it like this but ive tested with one of those batteries that go into a hand held camcorder and it worked like a charm [i dunno if that helps you tho].

**EDIT**
Your best bet is to find a battery supply from a computer and look at the links above that show you how to wire it up that way, VERY simple, i use the comp fan in my dryin room to keep currculation..