I had an ECHO battery (automatic vGo threaded 450-650mah battery) overheat and catch fire while charging in my bedroom. It was a small fire, with a bit of drama attached as the insides of the battery tube blew out against my bed frame and landed on the carpet. I never really got the scorch marks out to my wife's satisfaction. She was pregnant with our first child at the time, about 2 years ago, and she was very unhappy about that incident. She has gotten over it long since, but I still use a LiPo charging bag connected to a timer to charge my bigger batteries overnight - including my iStick 30. It just makes sense to do so after that one incident.
My eGo and iTaste V3 batteries don't get charged that way, just because I only have the one bag setup for charging on a timer, but I've never had an incident with them or any other battery, other than that one ECHO. I had several other ECHO batteries at the time, but nothing bad ever happened to them. Despite that incident, I liked the vGo threaded automatic ECHO, but needed to move on to other batteries in order to use better eGo and 510 threaded toppers becoming available at the time. I'm not even sure if the ECHO exists out there anymore. Some batteries, like the Halo Triton ones, still use vGo threading, but are still very limited in the toppers you can use without an adapter. All the adapters I tried back then sucked. I'm pretty happy with the gear I have now, so everything worked out in the end.
That scorch mark is still in my bedroom carpet to this day. It is barely noticeable now. Most days I don't notice it at all. It is there though. A constant little reminder of what can happen with these e-cigarette batteries if the one you're using wasn't put together quite right in the factory. That particular ECHO battery had been charged several times before without issue, so the fact that your battery hasn't caught fire yet is no indication it might not do so in the future. That being said, something like that could happen with nearly any rechargeable battery - like those in our cell phones, laptops and tablets, but it almost never does. Statistically speaking, that kind of battery violent charge failure is very unlikely to happen to you, but who wants to be the victim of a statistically unlikely event - that a few safeguards could have prevented from becoming fatal?
