My set up doesn't use batteries like that yet, but I'm thinking of getting a mechanical mod in the future. If I do end up getting one, should I always take the batteries out and store them in a case?
If your looking into a mechanical mod for the future, you have the whole world ahead of you. That said, for the love of all things sacred with our vaping community, do your research, and do it thoroughly. Once you do that, definitely give some thought to a Reo if you can handle the box format. I run mine with a modified Trident V2, and its like dripping without dripping.
That said, I very much enjoy the new Kanger Aerotank mini, and Aerotank Mega. I have both, and they're a super good vape. The Aerotank Mini would be a fantastic upgrade for your VV3. My wife uses one occasionally on her Vision Spinner. The new dual coils really let the juice flow and they do fantastic with 100% VG mount baker juices. Superb flavor and the airflow control is really cool too, even though I leave it wide open. With a 2.0 ohm coil, I run it between 4.8-5.5 volts on my E-LVT, and with the 1.5 ohm coil, 4.2 volts does nicely. Somewhere in the range of 10-14 watts or so, I don't bother with the math.