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Old 01-04-2012, 07:19 PM
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Question Maximum safe voltage to run a Canon EOS 400D?

Hi folks,

I've hooked up the 'fake' battery from a (non-functioning) AC-DC adapter to a 12V - 12V DC adapter (cigarette lighter plug into jump-starter battery pack on one end to standard DC plug/socket on the other). The DC-DC adapter I have supports (among others) 7.5V and 9V. If I run the 400D on 7.5V I get a low-battery warning and no function. If I run it briefly to test on 9V everything works perfectly - but I'm concerned about damaging the camera if I use it for prolonged exposures/cycles (e.g. 4 - 6hrs of 25s exposures with 2s between each exposure for startrails, etc.).

Does anyone have any solid data on what the maximum safe voltage is?


Many thanks,

Jessica
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Old 01-04-2012, 07:38 PM
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2stroke (Jay)
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Have you checked with a multimeter? 7.4volts is what the battery puts outs. Why not just use a 240volt invertor? What i think is happing is there isn't enough amps to power it or your dc step down tranformer is putting out 7.1 volts or something. Don't use it at 9volts, you will kill it by frying out the gates in the ic's or buring out power mostfos resistors ect. I wouldn't be using anything thats out more or less then 5% of 7.4 volts to be safe
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Old 01-04-2012, 07:54 PM
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Hi 2stroke:

The AC - DC adaptor that is OEM equipment for the camera runs at 8.1V, not the 7.4V of the battery. I'm not convinced that 9V is too far above that to cause damage, but I'm erring on the side of caution and seeking additional info from those who have already been down this road.

Running a power inverter is 1) inefficient, and 2) not currently possible because I don't have a working AC-DC adapter for the camera anyway.
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Old 01-04-2012, 07:56 PM
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Astroman (Andrew Wall)
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There are people who have run the camera on Model Aircraft Lipo batteries, these are 7.4v also (2S) As Jay said it may not have enough power or Amps for the Camera to function, or could be that the indicated voltage is not what is actually coming out. Look forward to your results.
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Old 02-04-2012, 06:54 AM
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acropolite (Phil)
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Quote:
If I run the 400D on 7.5V I get a low-battery warning and no function. If I run it briefly to test on 9V everything works perfectly
I wouldn't be running it at anything other than the voltage it is supposed to run on. Sustained low voltage can cause as much damage as excess voltage, Canon make 12 Volt adapters for SLR's the most flexible option would be to buy one.
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Old 02-04-2012, 07:52 AM
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Old NEC 2G mobiles (model "Mercury" and some others from that era) used battery adapter with 8.1V output. I have one, and I am waiting for the original Canon battery to die - and to use the battery enclosure as connector with this PS.

Sometimes it is not a very good idea to just flick old stuff in a trash bin
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Old 02-04-2012, 05:21 PM
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@acropolite: Unfortunately the adapters aren't available any more. Hence the custom job. :-/
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Old 02-04-2012, 06:09 PM
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Hi Jessica,
It is easy - just place a diode (for example, 1N4001) in series with your power supply - this will reduce the voltage by 0.7V, so you will have 8.3V, which is safe.
It would be good if you could confirm this with voltmeter, though.
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Old 02-04-2012, 06:47 PM
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mill (Martin)
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Most Canon camera's won't work on a low voltage or a high voltage.
I tested this with a variable voltage supply once.
The camera has some kind of voltage sensing internally and just shuts off when the voltage is too high or too low.
8.3 Volt is very safe in this case.
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