note, do your burn-offs with the cap removed, so if any odor is coming from body it doesn't 'contaminate' the cooling unit.
It may take a few days for some of the silicone parts to lose smell.
Batteries, we select them for safety and reliability (& trustworthy vendors) as much or more than we do for big mAh rating. Many here say avoid Amazon and only shopping by price/size.
Molicel P28A is one big ones here on FC. It is 2800 mAh. It does go a little farther than the battery included with Roffu, at least for me (idk what comes std in Roffu?).
I recently bought some
here.
I'm getting 4 to 6 three min sessions of 3 to 6 hits each. Below that (indicator on Roffu under 50%) I find that it doesn't seem to make as strong a hit, though it will keep going longer. I think that is somewhere around 3.7 volts or so.
My tendency is more to do a couple bowls and plug it in to usb-c, I like to just top it off. Battery life may not be maximized this way, but I generally get a couple of years from one, and they are not expensive.
Hope you enjoy your new device!