Question about batteries: I've heard multiple times that one needs to dedicate sets of batteries for a given mod. Various people have said to label (with felt tip pen or whatever) your batteries for a designated mod, and never ever use them between mods.
So my question is - why? Right now for example I have 2 x Samsung 25R sitting in my charger, fully charged. They've been used for a couple of weeks in my Waidea VaporFlask clone. What would be the problem with me now using that pair in the IPV4?
I can understand that individual batteries shouldn't be moved about, because you don't want to have a situation where you have one battery with a different charge level to the other. But if I marry them in sets of two, and always use a given set as a pair, does it matter if that pair is sometimes in my parallel-battery Waidea VF and sometimes in my series-battery IPV4?
In either case I'm always going to use them from fully charged to completely empty, then put them, as a pair, on my charger until they're fully charged.
TLDR: Can I label my batteries "Pair 1", "Pair 2", "Pair 3" and use any given pair in any dual-battery mod, or must I label them "VF Pair 1", "VF Pair 2", "IPV4 Pair 1", etc? And if so, why?