One of my friends gave me a Coolfire IV TC100 battery as a present and he said that is has been working properly since he got it. I went out and bought a new SMOK micro TFV4 tank for it because i had my last setup stolen, So I didnt have a tank. Whenever I put the tank with my Dad's battery, it works properly, and the same with my battery, but when I put them together, I have to hold the button and wait approximately 3 seconds before it starts producing smoke.