I don't necessarily think it's user error, it could well be the charger. You've gotten the same result with two of them, which is why I think you should get something else.
I suppose you've got a case for a return, if the output specs don't seem to match what is happening with your batteries (i.e. if it says "I will charge whatever batteries via whatever amount of current) and it's not doing so... Well, I guess at that point you could return it (maybe have the vape store owner "watch" the charger for 36 hours, or whatever). If that doesn't match the specs of the charger (which I do not know enough about to say) well, I'd imagine you could obtain a return.
Might be why this particular charger isn't talked about much on ECF, that no one is using it because it's unreliable, or because it has poor "specs" in terms of charging a battery. Some people don't want to charge fast, and actually consider fast charging to be harder on the battery.
So if the specs "match" up so to speak, do some research and order another charger. If you want something fast, I use a nitecore intellecharger. Not the priciest or maybe even "best" out of your options, but is surely is fast. Xtar is another maker I'd recommend.
As far as "user error" I have no idea, I was just stating that since you've replaced both the batteries and the charger once, and you can charge your batteries via USB, that is what is left, either user error (I know I can be fairly creative in "user error" mode so I'm afraid you'd have to do any detecting there, as nothing has been missed) OR the charger. I'm thinking it's the charger personally, and I'd recommend replacing it however you accomplish that. Etc.
Anna
