Battery life is totally frequency of use dependent. Where you get up to 1.5 days from an 18350 at 10 or so watts I get maybe 6 hours on a 2.5 at 7.5 or so watts on a ~2.5Ω coil using a Provari mini 2.5. Battery life is dependent on vaping style and varies widely.
Well yeah...I know that.
But the OP was asking for a ballpark, which I'm assuming he/she would gather from multiple answers to the question.
I was just contributing.
Personally, I really feel like I'm getting more life out of the P3...
With my v2.5's, I would get less than a day on an 18350...same Kayfun build (1.8 ohms), equivalent voltage (4.2 - 4.4)...
Like I said, this same set up gets me 1-1.5 days on my P3...so I'm finally able to use 18350 mode...and it's been nice! Using a v2.5 in 18490 mode just feels so big now.
All in all, I seem to be on the "longer battery life" side of things...I mentioned earlier, that some people have reported notably shorter battery life...but we all vape differently!
And to be quite honest, I'm sure PART of the shorter battery life they're experiencing, is just the fact that they can't put the P3 down!!! It's too fun to vape the NEW PROVARI!!! With every puff, my brain says "You're using the new Provari..." and it always feels exciting. Of course, even with my v2.5's, I still felt a surge of "Yeah I'm using a Provari." every time I'd take a hit.
"Off the top of my head, I'd say you're looking at a Boesky, a Jim Brown, a Miss Daisy, two Jethro's and a Leon Spinx, not to mention the biggest Ella Fitzgerald....ever."