Hi there
No worries about your English. I would have trouble with your language too
The Ijust3 came out a while ago now. It's likely the battery is getting old.
.15 is low resistance needing more power to make vapor. That is probably why you have this problem.
The Drag 2 uses 2 18650 batteries as you now know. If they are good batteries should be no problem for .15 coils.
Happy you got it figured out
I think for some reason people didn't see your first post. I didn't.
Glad to have you here with us.