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If you read through the links on the page linked to by Lotuselite above, you'll see that the more serious concern is non rechargeable lithium batteries. Based on the info provide there, it appears those batteries are very difficult to extinguish if they catch on fire, whereas rechargeable lithium ion are less of a problem. In any case, best to keep your batteries with you as carry-on. It would suck for your checked bag to be lost with all your spare batteries (and possibly also chargers), especially on some once-in-a-lifetime photo adventure.
I have traveled internationally with a Elinchrom Ranger Quadra kit containing four relatively large sealed lead type battery packs. Everything traveled in a Pelican as checked luggage and it was fine, and was inspected both by TSA going out and German authorities on the return leg. Those batteries though have a removable fuse, which I did remove to disconnect the external contacts from the actual cells. My impression is that the battery concern is more over high capacity lithium/lithium ion cells.
This link offers an easy to comprehend chart of what is and isn't allowed for carry-on and checked baggage: http://safetravel.dot.gov/quick_chart.html