yesterday I began using the ShenZhen Kanger Technology Co. Ltd 808d1 cartomizers I ordered with the USB passthrough I received in the same shipment. So far I have had a 100% failure rate (five cartos expired within a matter of hours). I suspect the problem is that they cannot handle 5v usage as I have experienced no failure at 3.7 volts. These would have come out of the factory in late April, early May. If any of you have had similar problems I would appreciate hearing about it.