Question - if your battery starts to go kaput, does the pass thru option still work fine on the X2's?
Plug in the cable and try it out. The blue light will glow on the end like it is charging. Then try to vape. If it won't vape, no harm no fowl.
Then wait about 20 minutes to give the battery time to get a mini charge and try to vape again.
I have been using the passthrough all day. I stopped vaping for awhile and the blue light went out. I just disconnected and vaped for awhile then plugged it in again.