If you have a T-Priv 3 Mod, the cable that came with it is NOT the charger. It is a data transfer cable that you can use to update your T-Priv 3 by connecting it to your computer.
The [3] batteries need to be removed from the T-Priv 3 (by opening the battery compartment on the bottom) and charged using an external battery charger (not included by Smok).
Hope this helps! I just got my T-Priv 3 a few days ago and am currently charging my batteries, so I feel confident that this should solve your problems.