If its not an AW 18350 it will most likely not fit. I tried to put a trustfire 18350 in my mini and had the same problem. The only reason I tried the trustfire was because provape forgot to ship the
batteries I ordered with the unit. Mine worked with the battery cap not screwed in all the way but it would stop working intermittently. So I stoped trying to use the trustfire 18350. I've noticed with many diffrent brands and even with the same brands that the sizes are very inconsistent. AW seems to be the most consistent!