HydraLight - No batteries. No charging. It simply runs on water!

Honestly, I'd kinda wondered that...that aspect is probably patented, I'd expect, it's clearly chemical in some fashion, though I actually don't have a clue...I suppose one could do a patent search for it to check, I just didn't have time, I'd seen it on cable TV by us, and figured it was too good to not just send in right then and there, you know?

It looks like it uses electrolysis. Not sure what the two metals are yet, but it doesn't actually run off water. It is the conductor. Apparently, salt water is more efficient. The ion transfer (somehow involving oxygen) is activated with the introduction of water.

From product reviews it sounds like the light vibrates after the wet fuel cell is put back in the light.