I work with a modified Canon 1100D camera, which uses the LP-E10 battery. The battery pack has the tiny nominal capacity of 860 mAh (Canon original), 950 mAh (some copy) or 850 mAh (some other copy), equalling 6-7 Wh. During a long photo session, and depending on the temperature, 2-3 batteries may go out from fully charged to blinking red, interrupting the photo session, and – on the long term – mean further replacement batteries. For comparison, a UPS battery holds at around 80Wh, at least on paper.
While the form factor is proprietary, meaning vendor (or at least product) lock in, the batteries are dumb. Luckily. Luckily the battery pack has no digital identification mechanism, so some crocodile clips are enough to replace them. No need to disassemble one to use the chip or something like that. So I got to work.
Stuff fail, this replacement battery developed a beer belly. I didn’t want to further invest into an already old camera, like getting a mains supply or further replacement batteries.
I didn’t want to take my camera apart (again) so I made a dummy battery that fits into the battery chamber. This proved to be a bit tricky, I needed to do some real sculpting but the end result is just what I needed. I also needed to get an idea about what’s under the hood: is the third pin functional, which pins are used, for what. This is what the battery pack looks like:
I also wanted to keep the camera functioning from an original battery, though I only use this one for astronomy. So the results of the sculpting:
Another piece of the puzzle: a DC-DC circuit. I had to choose and I chose the most flexible option: a buck-boost DC-DC voltage source, that can power the camera from virtually anything an amateur astronomer has at hand. I mostly work with 12V 7.2Ah UPS lead batteries, so that is one possible input.
Besides the standard UPS battery at 12V 7.2Ah, to which virtually all my systems connect (the guiding laptop through a boost, the mount directly, heaters directly), the camera can run on basically anything.
And the first deployment went exceptionally well, we’ve been joking about the camera not consuming but generating power. An all night session resulted in a 0.4 V drop from on single, fully charged UPS battery. I had some concerns about the noise the circuit may introduce, but it’s negligible.
As a possible upgrade, the box has some room (or ducttapeable surface) for an original battery, or a USB power bank, that could be wired through some diodes to offer backup should the main crocodile bite the air. But this is a minor concern, a battery is more than enough for a night.
Finally, a werk photo: