GH2 GH2 Power - specs, tests, DIY

Eugenio: I wouldn't recommend asking someone to make up a special unit for you using the components I mentioned. Building electronic devices is fine if you are a hobbyist, but it is very time consuming and you will rarely up with a device as compact, economical or as neat looking as a manufactured device. For me to design and build a regulated supply for the GH2 would take several hours and cost three times as much as an off-the-shelf device (if available). I'd have to buy the components, breadboard the design to test it first, then solder them on a circuit board which I'd have to make, add leads, mount everything in a case, and provide external connections. I suggest in your case to stick with off-the-shelf components bought locally.

For instance, if weight is not a problem, why not use a sealed lead-acid battery? Robust, reliable, lasts for years, cheap and readily available. As an example, here is a battery that would power a GH2 for a dozen hours or more and costs about $30 here in Australia: http://www.jaycar.com.au/productView.asp?ID=SB2486. Battery shops, motorcycle shops, all sorts of shops sell them. Another benefit, to charge it you could use a cheap 12-volt charger designed to charge car batteries.

You'll need a good regulated DC-DC converter, of course, and that's the tricky part. Automotive shops may sell them. Probably sell the battery too. And a digital multimeter if you haven't got one. Take a 10-ohm, 10 Watt resistor with you and do this:

1. Hook the regulator to the battery, the resistor to the regulator, and the meter to the resistor. Check the voltage across the resistor. If it is greater than 8.6 volts, buy battery, buy regulator.
 
g.l said:
It's a good idea, but do we know that the body would accept an 'official' battery that puts out more than the official voltage? I think it's likely it will detect that as a dangerous situation (assuming a battery malfunction) and shut down.

... or (reading your post again), did you mean with a DC converter built-in?
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Yes, you are probably right. A higher voltage from an official battery might cause the camera to shut down. Or it might wreck the camera electronics. The modified DCC8 that I am suggesting would of necessity (see below) have a regulator built in so that it outputs 7.2 volts.

I've been trying to think of a reason why Panasonic requires external supplies to be greater than 8.4 volts. The only one I have come up with is: for protection purposes. When running of the internal battery, there is virtually no possibility that an error can be made. The polarity is correct, the voltage cannot be too high. So the internal electronics can be powered straight from the battery. However, Pansonic may have decided that for external supplies, they had better build in some protection against wrong polarity and high voltage. They don't want cameras being returned because someone has applied reverse polarity, for example, and destroyed the internals. Such protection circuitry may require an overhead of a few volts. A possibility is that when an applied voltage of > 8.4 volts is detected, protection circuitry inside the GH2 is switched on, and that protection circuitry unavoidably causes a voltage drop of, say, 2 volts. i.e. for an external supply, maybe the GH2 isn't purposely cutting off at 8.4 volts, but it cuts off because the external 8.4 volts - 2 volts (assumed voltage drop in protection circuitry) falls below that required by the GH2.

If that is the case, it may be absolutely necessary to use a 7.2 volt regulator inside a modified DCC8, to prevent voltages higher than 8.4 volts (known to be safe) being sent directly to the camera internals, and to protect against user error (external supply being of wrong polarity, or voltage too high).
 
g.l said:
Similar simpler versions do exist on Ebay (everything included, just adjust a trimmer to set your output voltage). I have no idea how reliable they are, but they may be fine. They're called DC DC 'step-up' / 'boost' converters (smaller V in, higher V out), or 'step-down' / 'buck' (higher V in, smaller out). Make sure they handle your input V range (max & min charged state), and that you will input enough voltage for the desired output voltage (the step-downs typically need a bit more voltage going in than coming out).
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Virtually identical module with free shipping:
http://cgi.ebay.com/LM2596-DC-DC-Step-Down-Adjustable-Power-Supply-Module-/320570868469

UK link:
http://cgi.ebay.co.uk/LM2596-DC-DC-Step-Down-Adjustable-Power-Supply-Module-/320570868469
 
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Eugenio said:
This is the battery:

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=280538988771&ssPageName=STRK:MEWAX:IT # ht_6747wt_698

This is the regulator:

http://br.mouser.com/search/ProductDetail.aspx?qs=sSOk4GDDv7zfoj5u0nVBmg==

This two intens in the hands of a good professional electronics, along with the instructions here (regulator output at 8.6 v 1.5 mah), I am well served?

Thanks, I'm looking forward to starting construction.
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Regarding the battery: I think you will be disappointed. You get what you pay for. I doubt very much that a 12 volt, 6.8Ah Li-ion battery costing $30 (with charger) will retain its capacity after more than a few discharges. But it's only $30 so you haven't lost much.

As for the DC-DC regulator, the Texas Instruments requires extra components and someone to set it up for you: tell them 8.6 volts. No other specification is required. You may be better off with the cheap regulators mentioned by Chon (post above). It appears to have an on-board voltage adjustment that you could do yourself.
 
guyburns said:
Regarding the battery: I think you will be disappointed. You get what you pay for. I doubt very much that a 12 volt, 6.8Ah Li-ion battery costing $30 (with charger) will retain its capacity after more than a few discharges. But it's only $30 so you haven't lost much.

As for the DC-DC regulator, the Texas Instruments requires extra components and someone to set it up for you: tell them 8.6 volts. No other specification is required. You may be better off with the cheap regulators mentioned by Chon (post above). It appears to have an on-board voltage adjustment that you could do yourself.
Click to expand...

Regarding the battery, thanks for the tip, I'll keep searching and buy a good reference.

Regarding the voltage regulator, I have a professional who can configure it for me. I cherish the very security of GH2, and I want a good voltage regulator. In his opinion the voltage regulator PTN78000WAH is safer than the alternatives Chon?
 
Eugenio said:
Regarding the battery, thanks for the tip, I'll keep searching and buy a good reference.

Regarding the voltage regulator, I have a professional who can configure it for me. I cherish the very security of GH2, and I want a good voltage regulator. In his opinion the voltage regulator PTN78000WAH is safer than the alternatives Chon?
Click to expand...
Don't worry, the chip has both overcurrent limitation and overheating cut off. A bit overkill, but you could get a 5A regulator if you feel the need:
http://cgi.ebay.com/LM338K-DC-AC-6V-30V-Out-DC-4-5V-28V-5A-Converter-/290547727625
http://cgi.ebay.com/5-Amps-Voltage-Regulator-Module-Output-1-5-32V-LM338T-/130428364896
 
Eugenio: Your terminology is not correct. The AC adaptor for the GH2 is rated at 8.4 volts and 1.2 Amps (not 1.2 mah, which is milli-amp-hours). That means that if you draw a current of 1.2 Amps the output voltage will be a minimum of 8.4 volts (it could be slightly higher). Panasonic have decided that 1.2 Amps at 8.4 volts will power the GH2 under all conditions -- you do not need a regulator that can give more current as there is already a safety margin built in to the 1.2 Amp figure. Assuming the regulator you choose works to its specified ratings, a regulator rated at 1.2 Amps, or higher, will work correctly with the GH2. So you are correct in thinking that a 1.5 Amp regulator, "at most", will work okay.

If you are happy with the PTN78000WAH from Texas Instruments, go for it. It will work just as specified. Regarding the much cheaper units from Hong Kong, I don't know how they can manufacture them and post them so cheaply and still make a profit, given that the bulk price in the U.S. of the chip alone is more than the cost of the entire circuit board posted from HK (in lots of ten). Incredibly cheap. So cheap that I'm going to buy a couple just to play around with.
 
guyburns said:
The modified DCC8 that I am suggesting would of necessity (see below) have a regulator built in so that it outputs 7.2 volts.
Click to expand...

But if you do that, there's no need to pretend to be an official battery, just allow a wide voltage input range so people can use cheap AC adapters > 11V.

I've been trying to think of a reason why Panasonic requires external supplies to be greater than 8.4 volts. The only one I have come up with is: for protection purposes.
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There is no technical requirement at all, it's primarily so they can detect (and refuse to run) 3rd-party batteries. If the AC adapter (which doesn't have pins to ID itself as official) worked at the battery voltage, then 3rd party batteries would work too. So they have to use separate voltage ranges to allow AC adapters to work without the ID.

The clue is that the body turns on and runs, just to tell you that it refuses to run :). Of course the extra input tolerance is a nice side effect, but it's the first time I've ever seen it done. Most gadgets just die if you feed the wrong voltage in.
 
guyburns said:
Regarding the battery: I think you will be disappointed. You get what you pay for. I doubt very much that a 12 volt, 6.8Ah Li-ion battery costing $30 (with charger) will retain its capacity after more than a few discharges.
Click to expand...

Same batteries I have. Not tested yet, but cheap Chinese stuff isn't necessarily bad. It won't be as good as a quality brand (and often the quality control sucks), but I still expect plenty of use from them. With Chinese stuff I recommend buying at least two, that way you have a spare at critical moments. Better two lower-mah, then one high-mah when it fails :).

As for the 12/9/5V version, don't assume that the outputs will be tightly regulated. I say that as my 12V version (which is also not a multiple of 3.6V) drops from 12.6V->10.8V.
 
So you are correct in thinking that a 1.5 Amp regulator, "at most", will work okay.
Click to expand...

Using a battery of 8.4 V with 4.500mah (4.5 A) without the voltage regulator can cause damage to GH2?

This statement is correct or camera will have any security mechanism that ensures the consumption of only 1.2 A?
 
Eugenio said:
Using a battery of 8.4 V with 4.500mah (4.5 A) without the voltage regulator can cause damage to GH2?

This statement is correct or camera will have any security mechanism that ensures the consumption of only 1.2 A?
Click to expand...
The specifications say that that the camera consumes 3.6 W. For a 7.2V battery it comes down to 0.5A. Therefore 1 A or higher is plenty.
The 8.4 V battery cannot damage the camera no matter what its potential energy in Ah is. That number is just an indicattor how long the battery can last.
A 4500mAh battery will feed a camera consuming 500mA for 9 hours. The current flowing through the camera depends on its resistantance.
In the case of GH2 consuming 3.6 W from a 7.2V battery it is 14.4 Ohm. This is according to Ohm's law. I = V/R.
 
tyampel said:
The specifications say that that the camera consumes 3.6 W. For a 7.2V battery it comes down to 0.5A. Therefore 1 A or higher is plenty.
Click to expand...

Note quite as simple. 3.6W is likely an average, however the camera way well require more ocassionally in small bursts (eg. when booting up). Otherwise the AC adapter would be a lower spec.

The 8.4 V battery cannot damage the camera no matter what its potential energy in Ah is. That number is just an indicattor how long the battery can last.
Click to expand...
Yep, as long as the voltage is correct, any device will only use as much current (amps) as it needs.
 
Thanks tyampel.

A battery with these specifications:

DC input: 12.6V
DC output: 10.8V ~ DC12.5V
Rated current: 1000ma
Capacity: 6800mah

It would work perfectly with the voltage regulator PTN78000WAH?

Description of the voltage regulator PTN78000WAH:

1.5-A Output Current • General-Purpose, Industrial Controls,
• Wide-Input Voltage HVAC Systems, Test and Measurement,
(7 V to 29 V) VMeehdiicclaelsI,nMstarruinmee,natnadtioAnv,ioAnCi/cDsC Adaptors,
• Wide-Output Voltage Adjust
(–15 V to –3 V)
• High Efficiency (Up to 84%)
• Output Current Limit

Which left me in doubt was the "Rated current: 1000ma" of the battery in question.
 
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Which left me in doubt was the "Rated current: 1000ma" of the battery in question.[/QUOTE]

It probably means that the battery can sustain a 1000mA load without negative side-effects (such as overheating) and damage.
 
In my ignorance I thought that the voltage regulator needs an input voltage greater than 1.5 A.

I know one thing, in a week of reading I learned a lot about batteries and voltage regulators.

Yeah!
 
Eugenio said:
Which left me in doubt was the "Rated current: 1000ma" of the battery in question.
Click to expand...

Where did you see this?

As was said, it suggests that you shouldn't draw more than 1A from this battery, at least not continuously (the occasional burst may be OK, I'm not sure). But don't forget that 1A @ 12V is 1.43A @ 8.4V (so even with the 5-10% loss in the converter it should be OK).
 
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