I killed an old KR808D-1 manual (the kind with the totally open hole in the threaded end) this weekend during the long hurricane power outage when my only lighting was a pocket LED flashlight held between my teeth. I either overfilled or did not properly clean up a cartomizer in the poor lighting and it seems I got liquid inside the battery which led to it having a closed connection bypassing the pushbutton - same effect as if a button was stuck on but the button was not stuck at all. If I put a carto on it it started sizzling juice constantly. The battery was about 7-8 months old and it was my fault.
With the SmokelessImage Volt style of KR808D-1 manuals, the end is totally sealed. The button is tiny and recessed but the end if totally sealed. The newer style of manufacturer plain KR808D-1 batteries (and new Vapor4Life batteries should be the same) have what appears to be something inside blocking the threaded end hole. I have had no problem with either.
Joye 510 manuals are totally sealed metal on the threaded end and my only problem with them is &%#*&#*!# vendors who sell something as a 510 charger cable but actually send an Ego charger cable with too many mA output for a slim batteries. That will slowly degrade the batteries and ruin their ability to hold charge. I found the culprit cable out of my 4 (and now use it labeled and used as a Riva 510/Ego cable) and I bought a new 510 cable and 2 new batteries to replace the 2 that got hurt. Then I noticed the 2 new ones losing their ability to hold charge and I rechecked my cables and one I did not ever suspect - the reseller branded cable that came WITH my original 510 kit (clone stupid stupid I never bought a clone after that one) - that cable was putting out 420mA instead of something around 200mA GRRRRRRRRR. BUT other than stupid idiot vendors sending inappropriate cables, I never had a problem with them. My 8 month old Joye mega xl manual battery which was always charged in a different room where the cable is correct, is still working like a champ.
My 3.7v mod box works fine.
My Riva 510's work fine (fat battery 510's)