Last time I checked, you can check as many lion batteries you want as long as they are under the limit and "attached to a device". In my case that would be a charger. I ship one attached to my 8" monitor, and 6 attached to battery chargers, and I take 2 to 4 in the body case depending on the job. You can't ship batteries by them selves. Which kind of sucks, because in my opinion they are way safer in my battery case which has individual foam lined compartments for the batteries and they are less likely to short when dropped or run over by a fork lift, two of airline baggage handler's favorite past times.