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External power supply for DSLR camera

Angus Duncan

Jan 22, 2015
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Jan 22, 2015
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Hello,

I am trying to make an external power supply that can power my DSLR camera for extended periods (up to 12 hours) so that I can shoot long timelapses. Regular camera batteries only give a few hours, especially in the cold.

The camera can accept 7.4 - 9 V 2.5 A. I have a 15000 mAh battery that supplies 9 V 2.0 A (measured voltage 9.1 V). My question is, should I be using a DC voltage regulator to drop the voltage to something within the range that the camera can accept, and is the Amps difference between the battery supply and the camera an issue?

Any advice on this would be appreciated, I have little experience with electronics. Thanks.
 

Gryd3

Jun 25, 2014
4,098
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Jun 25, 2014
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4,098
Hello,

I am trying to make an external power supply that can power my DSLR camera for extended periods (up to 12 hours) so that I can shoot long timelapses. Regular camera batteries only give a few hours, especially in the cold.

The camera can accept 7.4 - 9 V 2.5 A. I have a 15000 mAh battery that supplies 9 V 2.0 A (measured voltage 9.1 V). My question is, should I be using a DC voltage regulator to drop the voltage to something within the range that the camera can accept, and is the Amps difference between the battery supply and the camera an issue?

Any advice on this would be appreciated, I have little experience with electronics. Thanks.
You want voltage to be exact or as close to the requirements for the camera.
If it accepts 7.4 - 9V than 9.1V will very likely be just fine.
As far as the amps are concerned... the rating on the camera is what it will 'pull'. The rating on your battery is how much it can provide. If the camera attempts to pull more than what is available, the voltage may dip. The voltage dip could be high enough to make the camera think the battery is dead, or cause some ... oddities with the camera behaving correctly. So.. to resolve this problem, you can hook up two batteries in parallel.
Just like jumper cables on a car. Positive to positive, and negative to negative.
You end up with a 'new' battery pack rated at the same voltage, but now twice the amps! (This also helps with the mAh rating... as those are additive as well)
So, short answer to your question, if to simply buy a larger battery with the required mAh, or connect more batteries together in parallel to create your own battery with the appropriate mAh.

(Remember. Your battery pack MUST be able to supply at LEAST what the camera is rated for in amps, and MUST be very close to the voltage rating of the camera)

*Special note when adding batteries in parallel!
-Make sure they are both fully charged or both very close to the same voltage. The batteries in a pack will try to balance each other out... so the lower voltage battery will draw from the higher voltage battery. If this difference is too high, the batteries can draw many amps from each other and cause overheating or other damage. (This is why jumper cables on a car can be potentially dangerous)
 

Angus Duncan

Jan 22, 2015
3
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Jan 22, 2015
Messages
3
Thank you for your reply Gryd3.

Is the 2.5 A marked on the camera the maximum current it will pull? For example, the camera can shoot film, which is by far the most power hungry mode when compared to shooting still photos. Can I assume that when in still photo mode that the current draw will be considerably reduced? I suppose I don't want to 'assume' anything when it could result in frying the electrics and be an expensive mistake.

Nikon makes a dummy battery that inserts into the camera and connects to an AC power adapter, which outputs 9 V 4.5 A. The dummy battery and cable is proprietary to Nikon, so I was going to use this and instead of plugging into an AC socket, hook it up to the external battery with a voltage converter between the external and dummy battery. However, as the external battery outputs 2 A, this is what will be supplied to the camera, even if the dummy battery is rated 4.5 A when coming from the AC converter, right?

I could hook up two batteries in parallel like you suggested, but ideally I was wanting an easily portable setup that kept weight to a minimum. Might be the only safe way unless I can find a battery that can output more than 2 A at 9 V.

Thanks again for your help.
 

Bluejets

Oct 5, 2014
6,901
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Oct 5, 2014
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6,901
Sounds like a job for a car battery ...40Ah..and a good regulator or inverter
 

Angus Duncan

Jan 22, 2015
3
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Jan 22, 2015
Messages
3
A 40 Ah battery is not very easy to hike up a mountain in the backcounty! Portability is important
 

Gryd3

Jun 25, 2014
4,098
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Jun 25, 2014
Messages
4,098
Thank you for your reply Gryd3.

Is the 2.5 A marked on the camera the maximum current it will pull? For example, the camera can shoot film, which is by far the most power hungry mode when compared to shooting still photos. Can I assume that when in still photo mode that the current draw will be considerably reduced? I suppose I don't want to 'assume' anything when it could result in frying the electrics and be an expensive mistake.

Nikon makes a dummy battery that inserts into the camera and connects to an AC power adapter, which outputs 9 V 4.5 A. The dummy battery and cable is proprietary to Nikon, so I was going to use this and instead of plugging into an AC socket, hook it up to the external battery with a voltage converter between the external and dummy battery. However, as the external battery outputs 2 A, this is what will be supplied to the camera, even if the dummy battery is rated 4.5 A when coming from the AC converter, right?

I could hook up two batteries in parallel like you suggested, but ideally I was wanting an easily portable setup that kept weight to a minimum. Might be the only safe way unless I can find a battery that can output more than 2 A at 9 V.

Thanks again for your help.
If you use the battery dummy and cable from Nikon, and connect your own real battery to it. The available power will be limited by your batteries.
As far as current draw is concerned. Film is usually a smaller frame-rate and would most likely be the most 'power hungry' when averaged out over time... but if the camera needs to charge the flash, or if the camera needs to instantaneously transfer a large 14+ Mega Pixel image to/from memory into storage this will most likely be a higher instantaneous power draw. (It may be short enough for 2A supply to handle... but it's always better to be safe than sorry.
Oh.. and I should mention.. if you get a 12V battery that can put out 2A, and use a switch mode voltage converter... you could set it to 8V and it can supply 3A. (Actually less... but if you use a switch mode converter, the available amps goes up if you decrease the voltage.)

Now battery wise... a car battery is a heavy choice... but anything you carry will be determined by how much power you need. So I suggest making a mock circuit with a smaller 12V Sealed Lead Acid. (From a small computer backup power supply, home alarm, or motorcycle battery) and seeing how long your time lapse holds out.
You can use this time.. and the mAh value on the battery to determine how big/small you can afford to go.
The lightest option would be Lithium based batteries... like those from RC toys like Traxxis.
 
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