Building an Offline Free Information Machine - Part 1.5 (an update)

I have a few updates to share on the resiliency goals from my original post, but also wanted to share that I’ll likely be holding off on most outdoors and solar testing until the spring. More updates to come, but winter in the mountains makes for poor testing conditions.

Goal and Progress

With an end goal of building a device that can be left running unattended outside for long periods of time (or ideally, perpetually), my first step was to get it running on battery power. I started by establishing a baseline for how long it could run on battery and if it could support full usage/load.

I chose a 10,000 mAh power bank and ran it through 4 full cycles. The average run time was just under 12 hours, although I think this can be improved (e.g. remove the extra cooling fan from the Pi.)

From here, my plan is to see if, how, and under what conditions adding a 30W solar panel will improve the run time:

• At full battery, what is the run time?
• At half battery, does the battery gain charge?
• When fully drained, can the battery be charged enough to power on the device and keep charging?

Each of these are semi-dependant on the results of the prior and also require ideal conditions (full sun, mild temperature.)

I did attempt the first test, but at around ~0°F/-18°C with some clouds, it was safe to call the results inconclusive, hence the delay for a bit.

Wrapping Up

While the outdoors component will have to wait for now, I will still be working on a more rugged enclosure. I currently have some recycled PETG on hand, which is temperature, water, and humidity resistant (it’s what most plastic bottles are made of.) Additionally, rather than designing from scratch, I am going to start with an existing model and make a few modifications - resizing, adjusting density, and adding internal rails to hold the Pi and battery in place - more updates on this and other 3d printing topics in future posts.

Lastly, a few folks have reached out with questions or to discuss similar projects, so keep that coming!