where can I find current-draw info? - Hotwire! Hardware Mods, Accessories and Insights - CHDK Forum
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where can I find current-draw info?

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Offline jimandy

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where can I find current-draw info?
« on: 29 / August / 2011, 10:39:12 »
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Just joined this forum having succesfully gotten my SD600 working with CHDK.  Several posts about external power for a Powerhot have been useful but I can't find the answer RE: learning the current-draw of the camera itself. I have just received an external AC kit which I bought mainly to get the DR60 DC Coupler (dummy battery) and I plan to connect an in-line current meter to get some idea of what the camera actually draws under different conditions i.e. sleep, shooting, LCD on/off etc. With a better understanding of current draw it seems like it would be helpful in estimating running time on various external sources where the AmpHour rating is known. If there exists somewhere this kind of current-draw info I would appreciate a link or post to refer to.
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Offline funnel

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Re: where can I find current-draw info?
« Reply #1 on: 29 / August / 2011, 16:40:06 »
To measure the power consumption you would need to measure both current and voltage at the same time to get some useful data. Shouldn't be a problem with the external adapter and a multimeter.
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Offline jimandy

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Re: where can I find current-draw info?
« Reply #2 on: 29 / August / 2011, 19:57:07 »
Yep, I am familiar with measuring current with a multimeter and have several in my shop.  In considering battery draw down, the tricky thing is that the current won't be consistent.  I assume there will be a peak flow when the shutter releases and an image is written to the card.  This will make estimating the current draw over time a bit iffy depending on the shooting mode and settings, i.e. interval. motion detect, etc.  My idea though is to get a rough estimate so that I can pick and choose from a selection of batteries with enough capacity to comfortably cover an anticipated time based on the nature of the surveillance project.
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Offline reyalp

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Re: where can I find current-draw info?
« Reply #3 on: 30 / August / 2011, 21:48:46 »
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Offline jimandy

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Re: where can I find current-draw info?
« Reply #4 on: 31 / August / 2011, 10:34:05 »
Yes, reylap, there's a lot of good info there, so much that my brain started hurting trying to read it all. A lot of his study seems to center on how low a voltage could be used with his camera and the methods of reducing powerdraw. Also there seems to be a lot about how much more power is drawn with CHDK running.  Too bad the link to the waveforms and measurements at http://bugsplatter.id.au/chdk/a590-power-2.html does not respond (times out without loading).

But there is a table in reply #11 comparing current (and power) at different voltages.   The current draw per the 3.2V entry is 374mA in Record Active mode and 109 mA in idle giving power draws at 1234 and 359 mW respectively. This is useful for my interest in the SD600 which uses the 3.7V battery. Being new to all this and not familiar with all the terms I am just guessing that "Record Active" is the period of time for shutter release and the storage of the image.
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