Here's a little prototype I've been working on which adds a simple battery backpack to the Raspberry Pi Zero.

- Youtube link
- Archive.org mirror
- Torrent
- Keybase mirror
- Source files

DESIGN

So as you can see, this little thing fits within the footprint of the Pi Zero, and it turns the Zero into a pocketable computer you could use for different local wifi and bluetooth applications.

It takes two AAA batteries, and depending on the quality of the batteries you get, you can expect 2-3 hours runtime. I chose AAA over lipo batteries, firstly because of the simplicity of the circuit, but also for the cheaper price, the size, and easy availability of the parts needed.

To use the device, you simply screw the battery backpack onto the Pi Zero. The contacts automatically make a solid connection to the 5v and Ground testpads underneath the computer board. You then add your batteries, and switch it on. Easy

The kind of applications I had in mind for this was for powering things like a pocket piratebox, or some other kind of temporary access point / captive portal.

HOW IT'S MADE

It consists of the following:

- 2x AAA Batteries
- AAA Battery Springs/Contacts - You can find these on ebay
- The innards from a USB female port
- 3D printed parts
- A switch
- 3.7v to 5v Step up Convertor - The batteries only output 3v, but it seems to handle it fine.
- Some thin wires
- 4x M2.5 8mm Screws

The circuit is very simple, connecting the 2 batteries together in series, and then outputting that through the step up convertor board. This takes the 3v from the batteries, and turns it into 5v for the Zero to run on.

The 3D printed part is split into two pieces, the first being the battery enclosure, with space for the springs and contacts, the switch and the little buck convertor.

Then there's the second part which connects directly to the Zero. I used 2 contacts from the female USB port, and they're placed in such a way that when it's screwed in, the contacts are forced up against the testpads underneath the Zero, providing a secure-enough connection.

The 3D source files for this are at the top of the page, so check that out if you want to make your own.

CONCLUSION

So that's the prototype for the Pi Zero Battery Backpack. A simple little project that may be useful to some of you.

It's worth mentioning that you shouldn't charge the Zero over USB, and have the battery on at the same time. It will mess the batteries up, and might brick your Zero.

Obviously as I develop this, I'll add a cover, or perhaps an enclosure for the entire thing.

Other than that, I just want to say thanks for the continued support, and I'll see you in the next video.

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BY NODE