so this just happened to me flying out of heathrow yesterday and im still a bit annoyed about it. had my 3 intelligent flight batteries for the mavic 3 in my carry on, all under 100wh each which i thought was totally fine for carry on. security pulled me aside and said i needed some kind of documentation or something? they were kind of vague about it and eventually let two through but made me check the third one which i know you arent supposed to do with lipos.

the battery made it fine obviously but now im paranoid. did i do something wrong or was that just an overzealous security person. cause ive flown with those same batteries like 6 times before with zero issues

heathrow security is notoriously inconsistent, ive had the exact same experience. technically lipos in checked luggage is a big no and most airlines prohibit it outright in their terms. the 100wh rule is correct for carry on but individual agents sometimes dont know the difference between watt hours and milliamp hours and get confused when they see the mAh rating on the battery. next time i just print out the iata dangerous goods exemption page and hand it over, usually shuts it down fast.

ugh that sounds so stressful. i always tape a little label on each battery showing the wh calculation worked out so its just obvious. like 4000mAh x 15.4v / 1000 = 61.6Wh written right on there. probably overkill but havent had a problem since i started doing it