I have triedthree different sub ohm tanks in my new Drag 2 and when I drawfrom it thereis a dio in power every so often. I woukd say it i take five draws there is a dio in one. My batteries are lghb2 18650’s they charge externally and are no more than a few months old. I was wondering if this is the device. It is still under thirty days old. Also if it isthe batteries is this a safety concern. They are in mint conditon, checked bear daily and never drained past fifty %. Thanks