A Long Overdue UpdateJuly 17, 2012
I know it’s been forever since I’ve done anything here. So here’s an update.
I’m in Madison, WI right now. Actually, I’m here for all of July. And I’m spending every waking hour when I’m not at my internship at Sector67, Madison’s hackerspace. This has posed a problem for me. I came here with the goal in mind of finishing my extruder prototype (which has been not being made for way too long), and maybe building a stupidly over-engineered bike light. And I’m pleased to say that I am now working on three projects, only one of which was planned. So here’s a quick run-down.
The OH GOD MY EYES Bike Light
Last year, I bought some LEDs because I like blinkies on a whim. Big LEDs. 5W big. And since then, I haven’t touched them. Mostly because I’m scared to run them at anywhere near capacity, because I value my eyesight. And now, I’m designing a light that uses one of them.
You may notice that it continues on my theme of using machined aluminum for everything, because I like aluminum and machining. Aluminum also happens to be a good material to make heat sinks out of, which is going to be needed. Any LED that will take 6.8V at 1A (yes, 1A) gets pretty toasty. So the whole body of the light acts as a heat sink.
I started by exploiting the fact that Sector67 has a CNC mill and making this overly circular mounting plate. It has three screw holes for attaching the LED, 3 holes for attaching the mount to the electronics, and a nice little cut-out to pass wires through. Which I conveniently placed right under one of the lobes of the LED board, so that it can barely fit the wires it needs to carry. Derp.
I then started making the standoffs out of hex stock and set screws, then got distracted by designing circular circuit boards for it, and then got distracted altogether by….
This is a charger. You plug it into a wall, it charges up, and when all is said and done, you can plug your phone (or other electrical gizmo) into it and charge it. They’re crap. And there are boxes and boxes of them at PS: One. And since stuff migrates, there is also a box of them at Sector67. So I cut one open to get at the rechargeable cells, and here’s what I got.
Two cells, wired in parallel. They’re 18650 size Li-Ion cells, and each one is rated at 3.6v, 2200mAh. Not shabby. So I hooked up one of the little packs, charged it up, and ran a discharge test at 1A, which is (unfortunately) the highest my charger will go. I got a capacity going from 4.12V to 3V of about 4600mAh. And according to this guy (http://budgetlightforum.com/node/7750), at 5A you still get a respectable 2200mAh (for a single cell). I’m in the process of tearing apart more of them to make battery packs, because, well, free Li-Ion packs! Which segues nicely into my next distraction….
Tiny Electric Bikes
Because working on the Power Racing Series has only made me love electric vehicles more, I have this thing. It’s a Razor PR200 pocket rocket, and it has a 200W DC motor on it, running at 24V. But I can’t have that, so I have a 3200W brushless DC motor and a Jasontroller on the way over from China. Combine that with lithium packs (36V at the weight of a single 12V battery from the original), and things should be interesting. To be continued….This entry was posted in Electronics, Vehicles. Bookmark the permalink.