Guys I just got my Cinegear solution and it seems to work GREAT. Build quality isn't too encouraging but if I take care of it it should be fine. They provide multiple mounting solutions and it just works from the start which is nice. I ordered an original Sony battery plus charger from them and a couple of generics from Amazon. The charger is a travel charger and still seems to be charging one after all night plugged in...I may try and find another charger if that's really how long it takes. Also the battery they sent also appears generic.

Will know more after a field test, but in general it looks like if someone wants a safe turn-key way to run the thing for days, this is it.

@sedlak Here is the only one that I could find that matches the ones that I bought. It is black and not silver, but the design and specs are the same.

http://www.ebay.com/itm/P18000-External-Battery-Powerbank-For-Apple-iPad-iPhone-PDA-MP4-Cellphone-/190808571721?pt=Other_Tablet_eReader_Accessories&hash=item2c6d13bf49

Wow, thanks! You really found one! I'd immediately jump on it, but the seller very clearly states he doesn't ship overseas (I'm in the EU), not to mention the shipping+taxes would probably make it over $100 and in that case it'd probably be safer to buy this http://www.energizerpowerpacks.com/us/products/xp18000a/index.html which goes for +/- $150 over here and seems similar, doesn't it? I'm still hoping for the ATC battery to be restocked by some chinese ebay seller :)

@zsero I purchased the Anker battery you have linked in your post and the official Panasonic DCC8 coupler, but I'm having no luck in powering my GH2. The first time I used it, my GH2 turned on for about 5 seconds before turning off, but it hasn't worked since that first time. The Anker battery is able to charge my other devices so I don't think it's the device.

EDIT 1: This is the battery I purchased: http://www.amazon.com/Anker%C2%AE-Astro3-10000mAh-Multi-voltage-output/dp/B005NGKR54/ref=sr_1_1?ie=UTF8&qid=1363211530&sr=8-1&keywords=anker+battery+3

Does anyone have any suggestions? Thanks!

EDIT 2: It turns out the stock Panasonic coupler is a dud (Bought it brand new from Adorama). I bought a third party coupler based on @Peter123456's recommendation and it's been working perfectly with my Anker battery.

Moved to http://www.personal-view.com/faqs/gh2-usage/gh2-power

@alexxela Thanks for such a detailed write up!

this is the step-down converter http://www.ebay.com/itm/LM2596-DC-DC-Converter-4-40V-to-1-5-35V-Step-down-Voltage-Regulator-module-/321029269473?pt=LH_DefaultDomain_0&hash=item4abed5e7e1

however, I noticed that by using a step-up/step-down converter like this one:

http://www.ebay.com/itm/3-5-28V-to-1-25-26V-DC-DC-Boost-Buck-Step-Up-Down-Voltage-Power-supply-Module-/280962204351?pt=LH_DefaultDomain_0&hash=item416aa702bf

you could still get some additional "juice" from the battery when the power starts to go down.

@Mike_C Yes, I can confirm! This is the converter I have used!

@Mike_C Yes, for some batteries you may get more out of it with a combi-converter. But I think in this case the battery is not properly selected. You should have selected a battery with higher voltage to better suit your application. But let me explain:

Moved to http://www.personal-view.com/faqs/gh2-usage/gh2-power

@HowardHC, @kin869, I bought the 10,000 mah Anker, and I tried it on the official Panasonic coupler, but the plug doesn't fit any of Anker's supplied plugs.

So, I ordered this aftermarket coupler (based on @ttruong's advice) and that one has a plug that fits: http://www.bestbatt.com/Panasonic-DMW-DCC8-Plus-DMW-AC8PP-Combo-p/bbdcc8.htm

I haven't tested it extensively, but it works fine so far. I will take it on the next wedding gig I have. I like how the Anker has a battery indicator.

The plug between Anker and Coupler is slightly loose, but I think a rubber band should be sufficient to give me extra security.

@kin869, there was no way to change the polarity, so it was plug and play.

Now I am trying to use the same setup with my GH1, but the GH1 coupler has a male plug rather than female plug. And, it doesn't fit in the Anker input plug. Does anyone know if I can buy a tip that will convert the GH1 coupler tip to the correct size for the Anker input plug?

Found another version of the ATC but with more juice on Amazon. It's a bit more but I think I'm going to grab another one!

http://www.amazon.com/Naztech-PB15000-Universal-Charger-Extended/dp/B007URKIGC/ref=sr_1_1?ie=UTF8&qid=1364235186&sr=8-1&keywords=powerbank+15000

@TGDude I doubt that you can run your Lilliput 5D-II/O/P with a Battery-Pack like the ATC PowerBank with 15000 mAh all day long. This Battery-Pack has got 55.5 Wh (http://www.naztech.com/naztech-cat-power-banks/285-naztech-product-bp15000-universal-power-bank.html I think it is identically constructed then yours http://www.personal-view.com/talks/discussion/comment/79529#Comment_79529). The Sony NP-F970 has got 47.4 Wh (http://www.sony.de/product/cac-batteries---chargers/np-f970). That is only about 18 % more energy the ATC can provide! That means you can run your Lilliput about 5 h instead of 4 h. But if you also want to charge your audio recorder then this ATC will not last much longer than 4 h. Don't forget the Lilliput has a power consumption of almost 10 W in comparison to the GH2's power consumption of only 3.5 W. If you put your expenditure in relation to the energy then the Sony is more worth the money (47.4 Wh / 33 $ = 1.44 Wh/$ vs. 55.5 W / 85 $ = 0.65 Wh/$).

Thanks @vicharris. That's the battery I was about to buy before I came across the ATC.

Thanks @alexxela. I didn't know the GH2 consumed so much less power than the Lilliput. If your numbers are accurate, then yeah I'm better off with the cheapo Maximal Power NP-F970. I feel like you just did my homework for me, lol. Great advice!