I have been vaping for about 2 months now and have 2 510 auto kits and an ego kit. All has been great for the most part but the other day one of my cartomizers quite literally smoked 2 batteries. I had only been using the cart since the day before. Either way I certainly know now that if you go puff puff and smell burnt plastic dont put that cart on another battery. What I really am looking for is how common is this. The supplier I bought the ego from doesnt even sell batteries for the unit and given 2 prior battery failures from the ego kit I certainly will not be buying another full kit.