To be safe:
* Batteries in a case in carry-on
* Mods in checked luggage
* Juice in checked luggage
* Tanks (with liquid) in carry-on liquids baggie
* Tanks (empty) in carry-on or checked luggage
That said, I have taken all of the above in carry-on with no issues... but... my juice was <100ml and my devices were regulated mods. Been to a few different continents with all this - no issues, not even any questions.