I recently took my Terkel light to Bonaire ... through security at Seattle, DFW, Miami, Curacao, Bonaire, Port-Au-Prince, and LAX (all the airports we visited round-trip).
I carried both it and my SEU's NiteRider in my backpack. The battery for the NiteRider is integrated into the canister ... you can't take it out. The battery for the Terkel light looks like three sticks of dynamite taped together with a couple of wires sticking out.
At every stop I had to watch while my backpack was searched. They run a little wiper pad over everything and check it for explosives, then they let you repack it and go on your way.
A minor inconvenience ... at worst.
FWIW - our checked bag containing our dive gear was searched by TSA in both directions.
So my recommendation is hand-carry the light. Make it easy to get to, and easy to repack. Keep a friendly demeanor. It'll work out just fine ...
... Bob (Grateful Diver)