It also depends a lot on the airport. And the country you are departing. In India they do not allow loose cells (and coconuts, BTW) and will take them away. Many of these rules are not based on real technical issues. So just stay within to avoid trouble. I've been asked many questions for bringing batteries and chargers with me. If you have them in your main luggage, photograph your devices at home and print out any of these information sheets. It usually impresses the guys and gals in many countries.
If you are just concerned about your own safety, just avoid shorting them, as usually. Baggage compartment has the same pressure as the cabin.