timmmay:Fred99: They don't tell you the voltage, but Wikipedia tells me that a single hydrogen fuel cell generates 0.6- 0.7V at rated full load.
2A max, or 8.5Ah could be really useful at 12v, but if it's 0.7v, I think I'll pass. I suspect that if it did produce a useful voltage, then they'd tell us. About the only thing you could use it for is to test a voltmeter. With three of them, you could get a red LED to glow.
It says "standard USB output", and the USB specificiations will definte the required voltage, I think it's 5V. No-one's going to release a product that just doesn't work, it'll get returned and they'll go bankrupt.
Edit - specs here.
OK. 2 core probably with boost converter to step up the voltage to 5v.
People do release products which don't work, and some do very well out of it. The entire global homeopathy industry is one example.