site banner

Tinker Tuesday for May 13, 2025

This thread is for anyone working on personal projects to share their progress, and hold themselves somewhat accountable to a group of peers.

Post your project, your progress from last week, and what you hope to accomplish this week.

If you want to be pinged with a reminder asking about your project, let me know, and I'll harass you each week until you cancel the service

1
Jump in the discussion.

No email address required.

Why consider?

It's a hard question. You're definitely looking at a lot more complexity and, unless you get into PCB manufacturing, a really trustworthy charger can get expensive. In turn, running low voltage inputs into a high multiplier boost converter is generally going to be low efficiency and high-noise. Depends very heavily on your comfort level.

I was a bit freaked out by LiPo watching videos of them burst into flames if they get ruptured. Maybe not something I want to attach to my helmet. But perhaps the issue is just as prevalent with 18650s?

18650s are just a form factor, but expect LiPo unless advertised otherwise. They're a little more resistant to puncture than pouch-style designs, but you're probably going to want a rigid cover regardless, both to protect against impacts, but also to avoid contamination.

Lithium-iron-phosphates are a lot safer and are available in 16850 format -- though they'll still discharge some heat and not-great fumes, even a direct puncture or complete short on a big battery pack won't cause a fire on its own -- but they're more expensive and finding a compatible charger is even more difficult. NiMH are cheaper and more widely available, but they have a much lower cell voltage and are pretty heavy for something to wear when biking.

The irony is my local library and (non-profit, communist) maker space all have 3d printers (multiple, even), but they're always broken.

Yeah, that's definitely a Thing. Especially the lower-end machines are always a battle to keep running.

As such I'm now currently trying to get pieces of acrylic, cutting them to size and seeing how sandwiching the ESP32 etc and wrapping the whole thing in a rubber gasket for light waterproofing works out.

That's definitely an option. I would consider switching to polycarbonate for the final version -- it's a little more obnoxious to cut with a saw (and can't be safely cut in any way involving heat/laser) and scratches easily, but you can bend it cold and it's extremely impact-resistant where even acrylic can shatter with jagged edges. But acrylic's fine for testing.

If you need a really weird shape or very thin gaskets, I'd also point to various automotive gasket makers. They're generally only useful where you have two surfaces being tightly screwed together and won't last for too long if you're repeatedly removing and reattaching things, but especially for rapid prototyping they're a lot faster and easier to work with, and surprisingly cheap (and actually can be purchased in Ace/Menards/Autoshops, even some WalMarts).