@bangkng: Original batery does have a chip.. that's why 7.2V is enough... for external power you need 8.4 at least... And as Vitaliy said, you can have even 20 of those batteries in parallel and run the GH2 for 20 days in row ;)
I have a bunch of these 14.8v batteries: http://www.all-battery.com/TenergyLi-Ion18650_14.8V13000mAhBatteryPackPCBandConnector-31047-02.aspx
Can I use this step down module to go from 14.8v to 7.2V?
How about to go from 14.8v to 12v for a Black-Magic camera converter? http://www.blackmagicdesign.com/products/atemconverters/
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