I own 4 nautilus tanks 1 full size and 3 mini. I noticed the bdc would only last up to a day. Once I tried the bvc they were much better. All the local stores were sold out of the bvc so I went back to the bdc. They are terrible . I've gone through 10 in just a few days. (Between me and my wife) . They usually work fine with the first tank but on the second tank they burn out and taste bad. The last one was the worst. It seems like they don't wick fast enough. I don't run the voltage very high and the juice is a 50/50 mix. I've gotten a week + out of a bvc so it's not the way I use them. I've been vaping for 7 months and no how to use my gear. I usually don't complain about things but the last coil was so bad it made me sick to my stomach. I don't know if you might have had a bad batch. And I did check code on the box for authenticity.