IKAN battery

has anyone used these yet? seems like the perfect solution for me.
i wonder how long a canon battery would power the camera?

http://www.bhphotovideo.com/c/product/9 ... Mount.html

ikan IBS-U65 BP-U Ultra-High Capacity Battery
http://www.bhphotovideo.com/c/product/8 ... acity.html

There was one of the reviewers testing them.. he said he had problems with the batterys that didn't have 12v.. instead of recharging the internal battery the "internal" battery just lasted an hour longer or so.. but then the camera came to a complete shutdown.. anybody experience with the ikans? They have 9V or 7,4V right?