@Ptchaw Sorry I wasnt trying to be a dick, I just heard allot of stories about people ruining their cameras with this stuff. Did you look at the Dolgin thing? Same issue about the indicator with that solution? I think its pretty cheap if you already have some HVX Batteries laying around.

http://dolgin.net/zen_dolgin/index.php?main_page=index&cPath=18&zenid=02ecc45460160bdfeaece68a21fe8929

@Ptchaw

To clarify: if you have the right connector/adapter, then you don't have to worry about the polarity? Or is there some further adjustment you have to make, even if no soldering is involved?

Secondly, what connector adapter does one get? Is it available on ebay?

@sam_stickland The cut off the GH2 uses to work out if it is on battery power is 7.4V, if I remember correctly. Lots of the early 3rd party batteries worked by using 7.4V as a way to work round the battery detection in the GH2, but of course you loose the battery indicator. I've yet to discharge my 12/9/5V battery, but I'll voltage check it when its nearly empty and see how it varies.

Why do all this risky bs>? Just wait for proper battery solutions...the switronix cable and battery is a much better idea if you ask me.I for one am not gonna "brick" my camera on some hacked battery -

@Retina That is correct. You should easily be able to find a transformer adapter for No. 3, but I am not sure of the type.

The GH2 coupler has the polarity marked on it; the outer ring is negative, with positive on the inside pin. So long as you stick to that, and 9V you're fine. I'd recommend checking it with a circuit tester just to be sure.

The kit battery is 1200mAh, the eBay battery is 8500mAh, so assuming the specs are accurate it should last over 7x as long. Have yet to check this though. At some point I'll see how long I can record for with it. I'm not sure what will happen when the battery runs out though (haven't had it happen yet). Depending on the voltage, the camera may switch off, or report that the battery is incompatible and (hopefully) gracefully stop recording.

I came across this and I wasn't sure if anyone has seen it. This system lets you use standard prosumer camcorder batteries with your GH2. If you have a rig and mount place this is an ideal set up. And its reasonably priced.

http://dolgin.net/Power-Lumix.htm

@ptchaw,

Is there a polarity switch on the connector/adapter tip -- the end you plug into the DC coupler?

Edit: Ptchaw, I just re-read your post where you discuss having to modify the tip. Never-mind.

@lolo Wasn't my idea, but thanks :) The indicator is just an led which lights up when its on/charging. I was hoping for some sort of charge meter that shows you how much capacity is left; you loose the power meter on the GH2 when using the coupler.

You can buy a DC coupler for about $40 - search DMW-DCC8 on Amazon/eBay. People made their own out of wood/mouldable plastic when they were out of stock - it's just a battery sized block with contacts on and a lead. Unless you are very hard up/cannot get one shipped I would just buy one.

The 9V lead with the battery won't quite fit into the coupler, I found an spare male plug from a transformer and soldered that on to the lead. If you do any DIY soldering make sure the polarity is right; you can kill your GH2 if it is the wrong way round. You should just be able to get an adapter that converts the connecters for transformers, though I'm not sure what size the coupler takes.

@Roy_Batty Dimentions are 126mm x 73mm x 25mm Initially cut a mounting plate out of wood, but I'm going to redo it with perspex. For now its cable tied to a rails block. The rails block is just a spacer for 2 x 15mm rails, with M4 threads on the bottom. My plate just has recessed holes for screws to screw into the rail block, to give a large surface area to glue the battery onto. Will post pics when done :)

@Ptchaw

What are the dimensions of the battery? What did you use to make the mounting plate?

@Ptchaw
Can you post a few pics? This looks really cool.

Can seriously recommend one of these for powering the GH2. http://www.ebay.co.uk/itm/5V-9V-12V-DC-Rechargeable-Li-ion-battery-CCTV-ep-/260844053351

Have tested and it does output a pretty stable 9V - works very well connected up to the DC coupler (or you can make your own). At 8500mAh it lasts over 7x as long as the official battery for 1/3 the price. Plus you can power USB devices and have a 12V for a monitor/light - all the outputs can be used at the same time. You could use a splitter if you want more devices. Mounting is a bit difficult, though easier than an RC car battery. I made a mounting plate for mine, glued on, which can then be screwed onto a rails block/flash hotshoe. Only thing missing from it is a charge meter.

Other than that, its really hard to find anything better that comes close to the price.

If the load is not more than 3A, this circuit (25$): http://www.dimensionengineering.com/DE-SWADJ3.htm is good for this use (downconvert 12V to 8.4). If you want a switching conversion (=optimum efficiency) a circuit based on National Semiconductor LMZ14203H - http://www.national.com/pf/LM/LMZ14203H.html#Overview can be used for maximum 3A.
The last switching circuit can also upconvert from 7.2 to 8.4.