Probably good advice just to be on the safe side of not having a “misunderstanding” with TSA.  But just to clarify, the fact is per FAA rules for Domestic travel (linked below) you ARE supposed to be allowed to pack devices with built-in Li Ion batteries in your checked luggage subject to capacity limits and taking precautions to ensure your devices cannot be inadvertently turned on.  However, from a practical sense, that is really not something you can typically ensure with something like a met