They look like they do, but admittedly the black front doesn't seem to accept the battery part as smoothly as the white one does. (I've only left 2 of the 5 out currently to prevent them from getting all mixed up)
I was thoroughly convinced it was the battery, but the black battery seems to work on either white or black "mod". The black front (with the board) seems to struggle at different times with either white or black battery.
I'm leaning towards it being the dna200 front mod section. And because it seems to work fine "when it works" I can't help but think it's a bad connection somewhere. I'm kind of lost as to what to check?
I think you have a jst connection problem but I want to give you some info on your other concerns also. I've got three of these and three spare battery packs, I have taken each one apart.
How hard the pack goes on or off could vary from mod to mod or pack to pack because of the designs of the two battery posts and the plugs. When I had a couple packs apart with the battery and connector out I could push one connector on at a time, I discovered a few things.
One is the posts on the mods are cut with four sections, if a pack is tilted when push on it can compress the four sections making the post a loose fit. Look at the posts each time you put a pack on and make sure the posts haven't been bent and the gaps to small, if they are use a razor knife of similar tool to gently open them.
The + & - plugs on the pack, I found burrs on the edge of the hole where the mod post enters, I used a larger drill bit, spun it by hand to just remove the burr and give it a tapper opening.
Doing these things, I still have one mod that battery packs just go on harder because the machining of the posts are rougher then the others, makes it feel gritty when pressed together. I'm sure over time it will wear in and become smoother, I'm not going to mess with it and make things looser!
I noticed each mod I've taken apart has had changes, they have obviously made improvements as they go. One of them, when I removed the board I noticed the jst pins were soldered on sticking farther out then the others. Under the plastic jst connector they had put two small plastic shims to push it farther to the back of the mod. I think what you
might have is one with the jst pins solder shorter on the board making the connection iffy and sometimes it works, maybe with certain battery packs? Whether yours has short jst pins or not, the symptoms your having all point to bad connections at the jst.
Unless you have the tools and are comfortable taking it apart to fix it, which will void any warranty, your best bet is to ask for a replacement. Ecig may be holding a few back just for warranty exchanges, I'd jump on it ASAP, worse they can do is say "so sorry". Hope you get it straighten out so you can enjoy it! Let us know how it goes.
