Last October my colleagues asked me to bring 4 spare Li Ion (obviously rechargable) battery packs for the drone they have in Kolkata. Each cost about 100€ and with all the drama about Li ion batteries I followed all the rules and carried them in my hand baggage. In BOM I duly put them in a separate bin like my laptop and once in the xray machine all alarm lights went off when they showed up on the screen. Supervising officers were called and registers opened. Li ion battery and drone were clear triggers for the CISF gentlemen which caused extensive debate amongst themselves and with me. Questions were raised where the drone was and that it should not be in my baggage. I don't exactly remember how I managed with my Tom Alter Bombaiya Hindi, but they let me go eventually.