IKAN adapter plate 12v battery question

I need to sort out a cheap and lightweight battery solution.
V-mount is not suitable for me (too heavy for handheld work)
I've been looking at the Ikan battery adapters that convert 7.4v to 12v but have heard of people
having problems powering their BMCC's?
http://ikancorp.com/productdetail.php?id=567
However, Ikan also do an adapter version for BPU style batteries.
Am I right in saying that BPU batteries are already
12v so it should work?
Are there any cheaper non-Sony alternatives to the BPU60 that would be compatible with the Ikan adapter?
Thanks for any help!
Jonty
V-mount is not suitable for me (too heavy for handheld work)
I've been looking at the Ikan battery adapters that convert 7.4v to 12v but have heard of people
having problems powering their BMCC's?
http://ikancorp.com/productdetail.php?id=567
However, Ikan also do an adapter version for BPU style batteries.
Am I right in saying that BPU batteries are already
12v so it should work?
Are there any cheaper non-Sony alternatives to the BPU60 that would be compatible with the Ikan adapter?
Thanks for any help!
Jonty