[arethuza]

According to their FAQ:

Can I bring a Reactor on a plane?

Yes. Per FAA rules every traveler can carry-on up to two Reactor sized batteries.

[NB I'm not saying I believe them - I wouldn't go anywhere near an airport with one of these things.]

[yread]

It seems you're right. It is allowed by FAA but disallowed by ICAO. I'm not sure I would take any chances with a 300$ device though

Passengers can also bring two (2) larger lithium-ion batteries (more than 8 less than 25 grams of equivalent lithium content per battery or about 100-300 watt hours per battery) in their carry-on.

http://www.faa.gov/about/office_org/headquarters_offices/ash...