Let's see, my case has six 78mm autos, 10 CE3s for those, an X2/650 with a T3, a spare T3 for the X2, a spare 18650 for my Vamo and, typically, a spare Protank and a couple of T3s for the Vamo. There's also thread adpaters, just in case, and a charger with adapters for the 78mm and X2, just in case. If I want to "show off" with something more "elegant" I'll take along an iTaste VV and a few 510 CE3s as well, but that makes it really tight in that case. In the car is a 12volt to USB converter, 2amp model...don't want to get caught unprepared.
I get a lot of "grief" about all the stuff I carry, but when I smoked tobacco, it was normal to carry at least a spare pack of cigarettes, or even more, when going out for the day. That meant forty or more "spares", and more cigarettes were always available just about anywhere. So what's the big deal making sure I can't run out of battery or liquids?