Some months ago I bought the above grip on eBay, shortly before it became apparent that there was something wrong with them: excessive battery drain, even in the switched off position. Pixel-Vertax admitted the problem and offered to exchange any malfunctioning grips for free (except the postage to send them back to Hong Kong).
As I don't use the grip that often I never got round to sending it back and the other day - when I needed it - decided to open it up first to see if there was anything obvious that could cause the drain.
It appeared that one corner of the PC-board that controls a number of switches and functions showed excessive solder that had not been cleaned off properly after hot air soldering the (surface mounted) components. The solder - in thin air blown strands - covered tracks and components and might have caused shorts or unwanted connections. I cleaned the board and re-assembled the grip. After 48 hours with fully charged batteries the grips does not show any battery drain and works OK.
Just to let you know....