I don't have personal experience but I have read multiple times is that you should keep pairs of batteries together, always using the same pair together in other words. Pretty sure the experts say to alternate top and bottom positions as well. Good info on this stuff over at the Vmax owners thread.
My post assumed (and stated) "matched pairs." Everyone is in agreement about the importance of that. Always use the same two batteries together when stacking. If one goes bad eventually, throw away the other one too.
My point was simply to assert that---since the top and bottom batteries may not discharge evenly---alternating the top/bottom positions upon re-insertion after charging could be done
consciously (by paying attention every single time) or
unconsciously (by ignoring their previous positions and not even thinking about which is re-inserted on top). Over many recharge cycles, random insertion will
tend to average out and be about as effective as conscious alternation.
Top and bottom position would not normally be important to protect the Vmax, since it will simply shut down if a problem arises with the batteries. Alternating top and bottom positions
might help to increase the number of recharges one can get from a given battery pair. Out of more than 100 Li-Ion/IMR/NIMH batteries I've bought to power mods over the past two years---especially dual-battery VV boxes and tubes---only about three batts have failed or reached the end of their recharge life. My oldest batteries may no longer provide as much vaping time after charging compared to my newer ones, but they all still recharge to 4.18-4.22 volts.
