The board on this unit though has a solid contact. I believe its the plastic one that came with the original flashlight. I don't see any distortion or melting on it. The solid contact is on the wider side so my original thinking that the battery's button top positive shifted a bit off the contact because of the wider ID at 19.4mm of the battery tube and long back spring on the end cap putting pressure might not be a issue..
I have some time today to do some testing as far as what I feel as battery warmth.
I'll also try some flat tops which have the wider positive to help with fuller contact?
I'm thinking I just ran longer at one point. The battery's were new, not to many cycle's of charging and showing equal discharge and re charging rates.
@Benn it's a side clicky with the original switch also if your curious..
@Paul, electronic's isn't one of my studies but is there any house hold products like a old DVD player, VCR, etc that I might fined a resister that will work?