Thought I'd throw this out there that at a show a couple of weeks ago my AD2K+ was losing power from the Naztech battery, making and losing continuity at the slightest bumping of my bag. Turns out that the connector on the custom cable that I was using has a short barrel, so it didn't slide down as far onto the battery connector as the stock cable connector. Apparently the connectors aren't all equal...some have longer barrels than others.
However, it was a simple fix in that the battery cover is plastic and that kept the shorter barrel from recessing down as far onto the battery connector as it could have. All I did was took an exacto knife and cut the plastic hole in the cover so that the hole was larger in diameter. This allows the shorter barrel connector to slide down alot farther onto the battery connector. Problem solved!
FWIW, I have both the Black Naztech and the generic silver model battery and they're the same design except for the color, so I did this to both batteries.