Panasonic GH4/GX7/GM5/GM1 with external battery pack - Page 1
Forum section: electronics / projects

author: Didix
author_rank: Regular Contributor
timestamp: January 16, 2015, 01:25:57 pm
content: I have a couple of Panasonic cameras (GH4, GX7, GM5, GM1) and would like to attach an external battery pack.External power can be connected by a DC coupler.However, although the regular battery runs on 7.6V, the voltage on the DC coupler must always stay over 8.4V.If it drops below, the camera resists to work.It seems, that the regular battery's built in circuit tells the camera "hey, I am an Panasonic battery, accept me".There are actually two pins beside Plus and Minus, that could provide such an information: D(ata) and T(emperature).Does anybody already have solved the puzzle how to connect a regular 2s LiIon battery to such Panasonic cameras?(Without boosting the voltage above 8.4V .. )How can I mimicry a regular Panasonic battery?-Didix

author: Didix
author_rank: Regular Contributor
timestamp: January 17, 2015, 09:07:31 pm
content: hmmm ..Is this the wrong section to ask this question?Or even the wrong forum?I would be happy if somebody could give me a hint, where to post this problem!-Didix

author: Didix
author_rank: Regular Contributor
timestamp: January 23, 2015, 05:15:48 pm
content: nobody using such a camera?-Didix

author: Didix
author_rank: Regular Contributor
timestamp: February 05, 2015, 04:30:21 pm
content: another desperate trial ...-Didix

author: mark03
author_rank: Frequent Contributor
timestamp: February 06, 2015, 05:07:18 pm
content: I don't have any of those camera (prefer Olympus for my u4/3rds). But I would start by building up jig of some kind that lets you access the D pin while the battery is in the camera and the power is turned on. Monitor that with a Bus Pirate (it's probably i2c) and judge how hard it would be to reverse-engineer and spoof. But it might be easier to just build your external power pack at whatever voltage you please (perhaps 1S for ease of charging) and use a hi-efficiency boost converter to get the appropriate DC input to the power jack.

author: Didix
author_rank: Regular Contributor
timestamp: February 08, 2015, 07:07:22 am
content: Hi Mark03thanx a lot for bringing some input to this thread. Different thoughts are very important!I was quite frustrated, that nobody was contributing so far ..Quote from: mark03 on February 06, 2015, 05:07:18 pmYes, that is exactly what I am doing so far. The boosters I tested so far are around 85% on a 1s which is not fully charged.If somebody knows about boosters that are much better, I would be happy, if they could contribute ..There is also a ready to go solution, since others have already testet that the Panasonic works up to 9V for sure:http://www.ianker.com/product/79AN7906-BAQuote from: mark03 on February 06, 2015, 05:07:18 pmIt's in my blood: I just do not like not to understand how things are workingI like the idea with Bus Pirate. I did not know that before. Good project!I have also googled a bit and there are sniffers for i2c on the Raspberry Pi too (which sits on my bench).However, this is also quite time consuming, since I had to build a spoofer.Well, and actually we do not know for sure whether it is i2c at all.I just could buy the cheapest 3rd party battery with a chip and use that chip only.But then I do not know how it works.Well, and this is of course one of the reasons why I am here-Didix