I saw this thread a few days ago. The next day I accidentally sat on my mod and it was very hot when I found it.. Battery wasnt fully drained, coil was black, wicks were dark brown, switch insulator wasn't melted, but my mod was very hot top to bottom. I took out the battery and it looked normal, no dark spots....threw it on the charger...the next day I used it with no problems but when I went to switch it out, I found these spots... Notice the 'spikes' and weird pattern it made. Battery is a VTC4 that ive had for about a month.