Sealed Lead Acid [Maker Update #57]
This week on Maker Update, an update for Circuit Python, Adafruit IO Plus, casting metal in Kinetic sand, a 3D printed tape measure tool, and reusing vintage voltmeters. This week’s Cool Tool is a 12v SLA battery.
Circuit Python 2.1.0 Released!
Adafruit IO Plus! The Adafruit IO Subscription Plan
Tips of the Week by Gareth Branwyn
Homemade Modern Sand Casting
Tape Measuring Tool by mikeasaurus
Reusing Old Meters by The Post Apocalyptic Inventor
Soldering Clean Wire Splices by bekathwia
ExpertPower 12V 7 Amp EXP1270 Rechargeable Lead Acid Battery
Extreme Max Battery Buddy
Maker Faire Istanbul Istanbul
Pueblo Mini Maker Faire Pueblo, Colorado
Maker Faire Bilbao Bilbao
Montevideo Mini Maker Faire Montevideo
Maker Faire Calgary Calgary, Albeta
Derby Mini Maker Faire Derby, Derbyshire
Thalia Mini Maker Faire Dresden
Texoma Mini Maker Faire Wichita Falls, Texas
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This week on Maker Update, an update for Circuit Python, Adafruit IO Plus, casting metal in Kinetic sand, a 3D printed tape measure tool, reusing vintage voltmeters, and hacking with SLA batteries.
It’s Wednesday, I’m Donald Bell, and it’s time for another Maker Update. I hope everyone’s doing well. East Bay Mini Maker Faire was beautiful this past Sunday. I saw a lot of friends and met a lot of new people too, and walked away with some new project ideas. If you need a reminder that humanity might not be doomed, I’m telling you, go find your nearest Maker Faire.
I don’t have any big projects I want to talk about this week, but there’s some news to share and lots of useful tips, so let’s get right into it.
First up some news. Adafruit’s Circuit Python API has been updated to version 2.1. If you’re unfamiliar, this is a barebones version of the Python programming language that’s compatible with a growing range of project boards made by Adafruit.
The updated software can be downloaded from Github. There are a number of bug fixes and updates, including a new pulseIO protocol that allows you to do to send or receive pulse-width-modulation signals over a digital pin.
The big upshot of that is the ability to work with servos, but also helps with some LEDs, and for buzzing piezos speakers and other stuff.
Adafruit also announced an update to their IOT cloud platform, Adafruit IO. In addition to the existing free plan, users can now subscribe for $10/mo to open up unlimited feeds and dashboards and two months of data storage. If you’re hot on making IOT projects, it’s a solid looking and fiercely open platform.
Lot’s of tips to share this week. On Gareth Brawyn’s Tips of the Week column on Makezine, there’s this cool idea for quick casting metal using kinetic sand and a tin alloy. A video from HomeMade Modern shows how to make a quick mold from kinetic sand and then casting a low melting point metal like this tin/bismuth alloy. The result looks great and doesn’t damage the sand.
On Instructables, Mikeasaurus shares the file for this 3D printed pencil holder add-on for a tape measure, allowing you to quickly mark your measurements. The printed part just fits right into the belt clip of your tape measure, making it pretty universal.
A friend of mine introduced me to a YouTube channel that was new to me called The Post Apocalyptic Inventor. He has a great, and thorough guide on reusing and modifying old moving coil voltmeters. He also has a great one on reusing motors from old washing machines.
Maker extraordinaire Becky Stern has a useful no-nonsense Instructable on best practices for splicing wires. I can’t tell you how many projects I’ve done with bad, or even dangerous splices. Hopefully this guide will spare some of you the trial and error of learning safe splicing technique.
And for a quick project I brought to East Bay Maker Faire last weekend, I loaded up a Raspberry Pi with the Museum MP4 software, to play a loop of videos on a tiny, portable cathode ray TV. I mentioned this software a long time ago, but this was my first time using it and it was dead simple.
Two things I realized while actually using it.
1. The software is setup as read only, so there’s no danger in corrupting the SD card by just switching the power off.
2. They’ve recently added the ability to connect a simple switch or button across two of the IO pins so that you can skip videos.
Aside from that, everything is deliberately kept super simple, making it great for kiosks and installations and even mobile things like what I did. Which, brings us to my tool of the week.
Sealed Lead Acid Batteries. In this Cool Tool’s review I’m going to show you why it’s handy to have a 12v, SLA battery around. This one cost me around $20 on Amazon, and you can pick up the same one using the Amazon link in the description, which helps support my videos and the Cool Tools blog.
The first time I encountered a sealed lead acid battery was in a Power Wheels kids ride-on car. Instead of having something like this take 100 D-cell batteries that have to be thrown away, the manufacturer mercifully includes a dedicated battery that can be recharged over and over again.
Like your basic car battery, these are an old school rechargeable technology. They’re sealed up completely, so there’s no major risk of spilling or chemical exposure unless you really work to crack these open.
The major downside to these is that they’re heavy. Compared to the LiPo and Lithium Ion packs in most of our gadgets, these things weigh a ton. But they come in a range of shapes and sizes, and a more standard range of voltages.
You do need to exercise some caution not to bridge the terminals accidentally, or they could spark, just like any battery. I’ll often store these with gaffer tape across them as insulation.
They’re very simple to recharge. I have this $17 Battery Buddy charger that I can just clip on and plug in and it charges automatically. Fancier RC battery chargers will typically have a setting for SLA too.
Now, here’s why I consider these a tool. I have used these multiple times to make plug-in 12v appliances portable. If you have a thing that you typically plug in using an AC adapter, that adapter is often doing the work to translate 110v AC into 9 or 12 volts DC. It will usually say right on the adapter.
For example, my family has this air mattress we use for camping and it came with an inflator that works off an AC adapter or car cigarette lighter adapter. But because I like inflating the bed in the tent, I just wired this up to use with the 12v battery by exposing the wires and putting crimp spade connectors on it.
As another example, I had this portable cathode ray TV that took 8 C-cell batteries or a 12v AC adapter. I just wired a barrel jack cable with crimp spade connectors and glued the battery to the bottom of the TV along with a Raspberry Pi that autoplays videos. It’s a little chunky, but it’s portable and rechargeable.
So that’s a look at SLA batteries. They’re heavy, but they’re cheap, durable, rechargeable and an easy hack for stuff that runs on 12 volts. You can pick one up using the link in the description and you can see thousands of reader recommended tools like this at Cool-Tools.org.
Maker Faires! It’s another big weekend for Faires. We’ve got Istanbul Turkey; Pueblo, Colorado; Bilbao Spain; Montevideo Uruguay; Calgary, in Alberta Canada; Derby in Derbyshire UK; Dresden Germany; and Wichita Falls, Texas. If one of those is near you, get out there. If the one near you stinks, go to Derby and say hi to my friend Dominic.
And that does it for this week’s show! Be sure to subscribe, leave a comment, leave a thumbs up, sign up for the email list to see extra stuff, have a great Halloween, and thanks for watching, I’ll see you next week.