I went mechanical because I got tired of 100 dollar VV mods only lasting 3 months because of a .22 penny unrepairable micro switch.
Clean and check your batteries every time you swap it. Torn wrapper will turn it into a pipe bomb.
Clean the threads every time you change the battery.
Lock it every time you put it in your shirt pocket and NEVER put it in your pants pocket.(multiple firey failures have occurred recently with unlocked and locked mods in the jeans.)
I change the battery at about 3.6 vdc cause thats when the vape starts to fade.
Try a rebuildable!