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External battery system works only for one picture!
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Author:  jfgout [ Sun Sep 13, 2015 6:59 am ]
Post subject:  External battery system works only for one picture!

Hi everyone, I'm encountering a very strange problem with my external battery system. I'm using a dummy battery (that one: http://www.amazon.com/gp/product/B00C9ZKFGI?psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00) to power my Canon 5dM2.
I use a DC-DC converter (that one: http://www.amazon.com/gp/product/B00Q48BRFO?psc=1&redirect=true&ref_=oh_aui_detailpage_o02_s00) to reduce the voltage from a Li-ion 12v battery (or any battery with at least 7.4v output) to 7.4 volts (which is what the canon original batteries provide).

After checking my voltage/polarity with a multimeter (not easy to do, the connectors on the battery are tiny and kind of buried, needs some very thin stuff to access it...) I insert the dummy battery in the camera and turn it on. Everything works fine at first. But as soon as I take a first picture, the camera turns off and displays an empty battery symbol. After that, I cannot use the camera until I turn it off, remove the dummy battery, re-insert the dummy battery and turn on again.
The one picture was taken correctly (I can see it in the review after rebooting the camera).

So, it looks like the camera performs some sort of battery check when it takes a picture and somehow my setup does not pass this test. Anyone has ideas about what the problem is?

I tried with several 12v sources, fully charged, and all show the same problem.

Thank you for your help!

jeff

----

http://www.jfgout.com

Author:  negativ3 [ Sun Sep 13, 2015 9:03 am ]
Post subject:  Re: External battery system works only for one picture!

It seems the Canon adapter pack puts out 7.6V.

Follow the link and check out the specs for the DC coupler.

http://www.bhphotovideo.com/c/product/590445-REG/Canon_3351B002_ACK_E6_AC_Adapter_Kit.html

Author:  jfgout [ Sun Sep 13, 2015 3:22 pm ]
Post subject:  Re: External battery system works only for one picture!

Thanks negativ3. I tried to increase the voltage to 7.6V but still the same problem. The camera works fine at first. I can review pictures, go through the menus, etc. But as soon as I take the first picture, it shuts down and simply displays an empty battery symbol.

jf

Author:  amongstmyselves [ Mon Sep 14, 2015 1:56 pm ]
Post subject:  Re: External battery system works only for one picture!

Does the dc-dc converter also turn off when the camera does ? Sounds like it is a faulty converter. I have a simpler DC-DC converter where you set the voltage with a 10 turn pot and there is no display but it works just fine with my camera. I use a multimeter to set the voltage. I think I may have the voltage a little higher as well. One thing you should do is set the voltage on the DC-DC converter while the camera is on as the camera will load down the converter hence reducing the voltage. Of course being very careful not to go to high with the voltage. It does sound like it is faulty though.

Author:  ansius [ Tue Oct 13, 2015 12:09 am ]
Post subject:  Re: External battery system works only for one picture!

when camera takes a picture there is a rather large power surge and the battery is capable of supplying it but you DC-DC converter is not. looking at the picture I see 330uF 50V cap on output, that is to small for sure. just add a 4700uF in parallel (you do not need more than 16V one) and it should do the trick. Or you can solder a larger one on board in place of the 330uF one. Also cable should nt be to long because when the current ramps up, you can start to lose voltage in cable, and it might drop below threshold.

when the shutter releases, converter is not capable to react to such fast discharge and voltage drops, and when it drops below certain voltage camera goes in safety mode, freezing all mechanical actions to not damage shutter and mirror assemblies.

Author:  amongstmyselves [ Tue Oct 13, 2015 1:21 pm ]
Post subject:  Re: External battery system works only for one picture!

Back you up on that suggestion ansius.

Author:  scotchtape [ Tue Oct 13, 2015 1:54 pm ]
Post subject:  Re: External battery system works only for one picture!

I also think you might be powering your camera with too low of a voltage.
Even though the battery says 7.2V a charged LP-E6 should be higher than that.

Most of the AC adapters provide at least 8V.

I think the charged voltage is like 8.4V but I am not sure.
You can measure a battery and check for yourself.

How big is your external battery? I built a dummy pack to use the Sony NP-F970 batts.
Each one is like 2x LP-E6s, and I run two in parallel so they are about 4x LP-E6s.
Actually I'm using Nikon right now but same thing for Canon.

I also tried using a converter and ran into similar problems but I forgot why or what I did.

The other thing is the battery meter - does yours work with the dummy pack?
If it doesn't, you can build your own dummy pack that will show the battery level.
Basically just sacrifice an existing battery and wire it properly. There's a few tutorials online.

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