T0NY58

I don't know why the problem is happening. But I know the SOLUTION!!! I had this issue with my DNA Z100C and it's definitely an over heating issue. But I switch to the higher resistance (ohms) coils. I have been using the P0.4/50-60watt/0.4 ohm coils instead of the 0.15 ohm coils and the problem completely goes away. If I had to guess, I think the added resistance in the coils wire absorbs the heat better and keeps the heat inside the coil, instead of the battery/board. Hope this works for you guys like it did for me.