UPS battery powered Canon

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.

beer belly battery

beer belly battery

beer belly battery

beer belly battery

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:

voltage

voltage

voltage

voltage

voltage

voltage

voltage

voltage

some turned-out-to-be-partially-useless reversed engineering :P involving a fridge :P

some turned-out-to-be-partially-useless reversed engineering :P involving a fridge :P

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:

the contacts are from a pcb

the contacts are from a pcb

the cable runs on the inside

the cable runs on the inside

it fits perfectly

it fits perfectly

and the lid can close normally

and the lid can close normally

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.

the box with the circuit fits into the blitz shoe

the box with the circuit fits into the blitz shoe

like a charm

like a charm

the box has the buck-boost circuit

the box has the buck-boost circuit

and two voltage meters for monitoring

and two voltage meters for monitoring

the red duct tape is for dimming the LEDs, night vision you know

the red duct tape is for dimming the LEDs, night vision you know

and it works from 12V, or whatever voltage the battery holds

and it works from 12V, or whatever voltage the battery holds

I have other boxes like this, and programmers know the importance of documenting shit :P

I have other boxes like this, and programmers know the importance of documenting shit :P

the V meters aren’t the best though

the V meters aren’t the best though

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.

A small 6V 4Ah battery

A small 6V 4Ah battery

It even runs from a USB power bank, FTW

It even runs from a USB power bank, FTW

and the battery is… full

and the battery is… full

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.

The box little box and the extra wires get lost in the tech already put onto the scope

The box little box and the extra wires get lost in the tech already put onto the scope

the camera after the long night

the camera after the long night

Houston, we have NO problem

Houston, we have NO problem

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:

Messier 46

 

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