Last year I bought a Canon PowerShot SX200 on ebay. I wanted to play a bit with CHDK, the Canon Hack Development Kit to make some timelapse things. Problem was, the battery would hold only up for 2 hours or so. Even worse, the camera has no power jack to attach a power supply. The solution is to buy a battery dummy that has a jack on its back. That costs like 30 euros!
3D printing to the rescue!
Last christmas I bought myself a RepRapPro Huxley Kit. It took quite a while until I got to the printing. Changed from the melzi board to a Sanguinololu board, because I smoked one of the stepper drivers and failed replacing it. Also I had a lot of problems with the bowden tube popping out of the extruder all the time. I think it was because my temperature was too low. Anyway, now it seems to work. Still I have to do some tweaking on the parameters.
The model
I measured the original battery and used OpenSCAD to design the model. It takes a while to get used to it but I think I like to write some kind of source code to construct a 3d model.
This is how it came out of the printer, next to the original battery. Actually this is the second one. The first was a bit too thick to fit into the battery compartment. The weird looking plastic stripes at the slot at the front result from a messed up support structure. A bit of cleaning had to be applied.
Wiring and Assembling
I used this tiny 4mm jack and glued it into place. For the other connection I used a tiny one sided copper board. I had to file it a bit down, it wont fit otherwise. Then simply made three tiny pads by scraping off some of the copper. Next soldered two wires to the left and the right pad, the middle one is not connected. The solder joints are quite big blobs. That’s because the tiny PCB didn’t want to connect to the camera at first.
Testing
Guess what, it fits and it even works. I set the power adapter to 4.5V, which is a bit more then a full loaded battery. The power adapter should be rated at least with 2A @ 4.5V. First I tried one with 1A and it starts the camera fine, but the cam shuts down as soon as it tries to drive the lenses.
Links
- OpenSCAD model at Thingiverse. Yay, my first part on thingiverse!
tinkerlog 
I was wondering if you ever found out (or perhaps already knew) what the middle pad is for? I was in the process of CNCing a *Fake battery* for my canon A3300 for the same reasons, and was considering leaving the middle pad out. Do you know of need for it?
And again, many thanks for posting your experiences. I took your advice on the barrel jack, and I’m sure this saved me TONS of time searching for one small enough to fit (the AS3300 has an even smaller battery than the SX200). Cheers, and best of luck to you!
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The middle pad is usually used for a temperature sensor inside the battery and is used during charging. If the battery gets too hot, charging is aborted until the temperature has dropped to an acceptable level. It should be safe to omit the middle pad in dummy batteries, or if the device won’t operate, try a resistor (about 10k) between the middle pad and ground.
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