I use 900mAh batteries in my protege, and if I am just sitting constantly vaping I'll have to swap them out every 2-3 hours. If I'm at work though normally one battery will last me the entire shift, unless of course I end up getting stuck in the restaurant doing paperwork then I'll run through 2-3 batteries.
I have four with me at all times (because you never know) in a hard cigarette case along with four extra Kr808d-1 cartromizers. It's not an issue as the case is not different than when I carried my pack of marlboro smooth 100's, actually maybe smaller