Picture of cheap and easy PSU for Canon EOS
I think lot of guys here on Instructables know how much satisfaction is obtained building a gadget entirely by ourselves, but... sometimes it could be a clever solution opting for some nice and ready accessory. I think this is one of these cases.
I recently had the need to have a power supply for my Canon DSLR, an EOS 40D, to make some timelapse. For this pourpose I've bought an LM2596S step-down adjustable power supply module from eBay, it's very cheap, efficient, compact, and (I hope) safe... and it fits exactly inside my exhausted lithium battery case. And this instructable could be handy adapted for almost any digital camera battery, the only requirement is that the case contains the power supply module.
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Step 1: Intro

Picture of intro
The new psu is intended to work with a wall-plug transformer the same as with any DC power source between 9 and 35V, as a car battery or almost any wall-plug psu. This could be very handy in case of timelapses, gigapan shots, or long movies.

Step 2: What's inside?

Picture of what's inside?
I've made the same modifications on two batteries, because both of them were exhausted. They weren't Canon batteries, indeed the original ones are almost ethernal.
You have to cut/crack the plastic casing all around the perimeter, because it's glued verty sturdy. Inside you'll find two 18490 Li-ion batteries, which are very rare to find to replace.

Step 3: Keep the shells

Picture of keep the shells
Separate the battery parts unsoldering the battery contacts, and clead the case edges with a cutter, they should fit each other so we'll glue them at the end.
Maybe you wish to keep the protection circuit as replacement...
mcvapes4 months ago

Thank you so much for the guide. I was just looking into using this exact converter. However, I am concerned about the heat. According to the spec sheet for the LM2596S, a heatsink should be used when over 10W. The stock batteries are rated for 7.4V at 2A. Unfortunately, I don't have the tools to measure how much power the camera uses. Have you ever checked for heat build-up in the battery enclosure after prolonged use? I

andrea biffi (author)  mcvapes4 months ago

I doubt the camera has a peak of more than 10w. Batteries are so powerful to last many hours. I never checked the heat, but I used for time lapses so there is a certain interval between pictures and certainly enough time to heat down.

Video mode on new cameras could be different, but you can always check if the psu is hot after some minutes of video.

meanpc2 years ago
Nice job! Would be nice if Canon included a DC input from the factory, wouldn't it? Especially since we are using them for video a lot now, which burns a ton of battery.
Can you show the camera with your battery installed? I would like to see how you have the wire routed.
andrea biffi (author)  meanpc2 years ago
Yes I'll take the picture soon. Canon always wants to sell more accessories, see also timelapse features or flash transmitter... :-(
If you don't want to risk burned fingers you can order something that works like this for the Canon T2i on Ebay for around 10 bucks. If you have a larger capacity 7.4 volt power source (e.g. old canon camcorder battery) the dummy battery part of the above adapter can always be cut off and used instead of the AC adapter.
andrea biffi (author)  archp20081 year ago
Thanks for your advice, I've been using my DIY PSU with success for last seven months with not a pinkie burned ;-)
My power source is 220VAC or 12VDC, this last connected directly to my dummy battery.
tvm7772 years ago
Its a good solution, i have a 550D, same solution for it??
wich module did you use? i find this one cheap:
andrea biffi (author)  tvm7772 years ago
that seems right, you can found other ones clicking on the link in the first step
8steve882 years ago
Hi there.
Great Instructable. I have an EOS40D and reckon your solution it would solve another problem as well. - Do you know if your battery has enough charge left to power a sensor cleaning session? With this solution it doesn't matter - just plug in and go.
Even with my battery grip -two batteries- I have to recharge just to be sure that the large drain of holding the shutter open won't flatten the batteries. Problem solved. Thank you.
andrea biffi (author)  8steve882 years ago
that seems right, you can found other ones clicking on the link in the first step
andrea biffi (author)  8steve882 years ago
yes, also Canon recommends using the PSU to clean sensor.
jamesobrady2 years ago
Great instructable !!
On the protection diode, have you wired it in parallel with the supply?
andrea biffi (author)  jamesobrady2 years ago
Yes, with reversed polarity.
andrea biffi (author)  andrea biffi2 years ago
then I decided to not add any protection diode, in parallel is too dangerous due to diode blowing, and in series it takes 0.7V (or 0.35V for a Schottky diode), so I decided to trust in circuit own protection.
lionel10242 years ago
andrea biffi (author) 2 years ago
Thanks! Your comment really helps me. I actually had some doubt about the way to add the diode. I didn't want to lose power (especially with an external battery supply), but you're right about diode blowing... I'd have to think about that.
Yes, maybe 0.7V are not too much, and a better protection should be good, I don't know what could happen to the circuit with a reversed voltage from a car battery with 50A... I'll update the circuit and the Instructable...
I'd like to see how this fits into the camera.
That's what I came to say. I like the idea, but no way would the batter fit back into the camera.

Andrea, can you show us how that works?
andrea biffi (author)  sdtacoma2 years ago
Of course!
Very cool. I don't think my camera has that little "door" so I wasn't sure how that was going to work. Thanks for the update. Great photos BTW.
Yes, I have the Canon XTI and the battery tether port is different. May still be doable though. photo from:
g elliot s2 years ago
why not just buy one that's made for the camera?
Treknology2 years ago
Even when new, I've yet to see a video camera with a battery that can outlast a single cassette. My solution has been to build a bracket that holds that camera and supports an SLA battery on the shoulder (also a major improvement in stability). I never thought of publishing it because most people complain about the weight of the battery!
Helperlein2 years ago
The batteries give a voltage range between 8,4V and 6V.
Why didn't you just take a 7,5V external PSU instead of a PSU plus a Step-Down to 7,4V? At least if somebody does not have PSU yet, I would recommend just to buy a PSU with the right voltage and they are almost done. No voltage error, plus wiring is one step easier
andrea biffi (author)  Helperlein2 years ago
And with Canon unfortunately an external PSU isn't enough because Canon EOS have no DC-IN female plug.
andrea biffi (author)  Helperlein2 years ago
Hi, one reason is that I've tons of 12V DC and 9V DC PSU, because almost all devices uses that voltage (some uses 5V too) and when device breaks it left the PSU well functioning. As I've lot of them I assume many people have at least one of them. Then there is the main reason: with that you can use any battery from 9 to 35V, included a car-battery of 12V. There is more: if any device in your equipment is powered with a similar PSU you can use the SAME battery to power them all.
andrea biffi (author) 2 years ago
Here is the image of the battery in position, note the rubber door, I think every Canon EOS has it..
KT Gadget2 years ago
What you could do for the LED indicator is remove the SMD LED and replace it with a extended wired LED to point out of the pack, or get one of those bent acrylic pieces that are used to show the indication bars when the lights can't be flush with the case (not sure what they are exactly called).

Nice ible though, this might be one I will use in my Olympus when I get to more extended pic/video projects. Have you tried it through a 12V car plug to see how it performs?
andrea biffi (author)  KT Gadget2 years ago
the battery should fit inside the camera, anyway it could be useful to see if power reach the battery.
I think Olympus has a DC-IN power plug, you don't need this (if you have the right voltage power supply).
I didn't try 12V car plug, but I've tried 35V and it works good.
Helperlein2 years ago
Adding to the comment below, I think it is more important that the power supply, internal or external, can give enough amperage. It would be useful to know this for anyone who would like to use this (100mA, 500mA, 1A, 2A,..?)
andrea biffi (author)  Helperlein2 years ago
Almost all wall-plug 12V transformers have 1A amperage. These work good, maybe you could try 0.5A too, but I doubt it's enough. Any battery more than 1A is good. I think 9V 200mA are too weak.