It's unclear to me what the official requirements are. For example this is from the TSA's site: "Devices containing lithium metal or lithium ion batteries shou

It's unclear to me what the official requirements are. For example this is from the TSA's site: "Devices containing lithium metal or lithium ion batteries should be carried in carry-on baggage. Most other consumer electronic devices containing batteries are allowed in carry-on and checked baggage." Taken literally, this is of course widely ignored. There are also various requirements around spare batteries that do include capacity limits.