For still pictures I’ll be using my Canon IXUS 50, a tiny camera that takes excellent photos and weighs a fairly low 135g. However a test a couple of weeks ago showed that it only manages about 600-700 shots on a single battery charge (with display off – that makes a big difference), over a period of less than 2 hours. I would like more shots and I need more time than that, so I’ll be using external Lithium cells to run the camera. Like many Canon cameras it doesn’t have a power socket, but instead you’re supposed to buy the special Canon power adapter that comes with a dummy battery that slots into the camera.
A cheaper option is to take apart an old battery and use the casing! So that’s what I’ve done here:
The wires run through a hole that Canon incorporate into the camera battery cover, and is normally plugged by a little rubber cover.
Using this “battery” I tested the minimum voltage the camera will work at (3.1V) and how much current it takes (lots!). I also determined that switching the display off saves about 60% of the power requirement.
In the balloon payload, these wires will run to a simple regulator that protects the camera when the batteries are new. It may be that the camera would be OK anyway, but Canon don’t specifiy a maximum voltage (though I do know their adapter puts out 4.3V – less than the Lithiums I’ll be using), but I’m not about to risk destroying the camera to find out!