Fail Of The Week: Taking Apart A Tesla Battery

September 7, 2019 by Bryan Cockfield 86 Comments

It takes a lot of energy to push a car-sized object a few hundred miles. Either a few gallons of gasoline or several thousand lithium batteries will get the job done. That’s certainly a lot of batteries, and a lot more potential to be unlocked for their use than hurling chunks of metal around on wheels. If you have an idea for how to better use those batteries for something else, that’s certainly an option, although it’s not always quite as easy as it seems.

In this video, [Kerry] at [EVEngineering] has acquired a Tesla Model 3 battery pack and begins to take it apart. Unlike other Tesla batteries, and even more unlike Leaf or Prius packs, the Model 3 battery is extremely difficult to work with. As a manufacturing cost savings measure, it seems that Tesla found out that gluing the individual cells together would be less expensive compared to other methods where the cells are more modular and serviceable. That means that to remove the individual cells without damaging them, several layers of glue and plastic have to be removed before you can start hammering the cells out with a PEX wedge and a hammer. This method tends to be extremely time consuming.

If you just happen to have a Model 3 battery lying around, [Kerry] notes that it is possible to reuse the cells if you have the time, but doesn’t recommend it unless you really need the energy density found in these 21700 cells. Apparently they are not easy to find outside of Model 3 packs, and either way, it seems as though using a battery from a Nissan Leaf might be a whole lot easier anyway.

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Reducing Drill Bit Wear The Cryogenic Way

September 7, 2019 by Bryan Cockfield 13 Comments

There are a lot of ways that metals can be formed into various shapes. Forging, casting, and cutting are some methods of getting the metal in the correct shape. An oft-overlooked aspect of smithing (at least by non-smiths) is the effect of temperature on the final characteristics of the metal, such as strength, brittleness, and even color. A smith may dunk a freshly forged sword into a bucket of oil or water to make the metal harder, or a craftsman with a drill bit might treat it with an extremely cold temperature to keep it from wearing out as quickly.

Welcome to the world of cryogenic treatment. Unlike quenching, where a hot metal is quickly cooled to create a hard crystal structure in the metal, cryogenic treatment is done by cooling the metal off slowly, and then raising it back up to room temperature slowly as well. The two processes are related in that they both achieve a certain amount of crystal structure formation, but the extreme cold helps create even more of the structure than simply tempering and quenching it does. The crystal structure wears out much less quickly than untreated steel, therefore the bits last much longer.

[Applied Science] goes deep into the theory behind these temperature treatments on the steel, and the results speak for themselves. With the liquid nitrogen treatments the bits were easily able to drill double the number of holes on average. The experiment was single-blind too, so the subjectivity of the experimenter was limited. There’s plenty to learn about heat-treated metals as well, even if you don’t have a liquid nitrogen generator at home.

Thanks to [baldpower] for the tip!

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Is Solar Right For You? Find Out!

September 7, 2019 by Bryan Cockfield 22 Comments

Solar panels are revolutionizing the electric power industry, but not everyone is a good candidate for rooftop solar. Obviously people in extreme northern or sothern latitudes aren’t going to be making a ton of energy during the winter compared to people living closer to the equator, for example, but there are other factors at play that are more specific to each individual house. To find out if any one in particular will benefit from solar panels, [Jake] and [Ryan]’s solar intensity sensor will help you find out.

The long-term intensity tracker is equipped with a small solar panel and a data recording device, properly contained in a waterproof enclosure, and is intended to be placed in the exact location that a potential solar installation will be. Once it has finished gathering data, it will help determine if it makes economical sense to install panels given that the roof slope might not be ideal, landscaping may be in the way, or you live in a climate where it rains a lot in the summer during peak production times.

As we move into the future of cheap, reliable solar panels, projects like this will become more and more valuable. If you’re not convinced yet that photovoltaics are the way of the future, though, there are other ways of harnessing that free solar power.

Solar-Harvesting Blinkenlights

September 3, 2019 by Bryan Cockfield 15 Comments

A few years ago a fad ripped through the makersphere where people would build cheap, solar powered LED blinkers, glue a magnet to them, and throw them on anything metal. It was an interesting time, but luckily did not last for too long. With some effort and craftsmanship, though, the solar throwie idea can be turned into something more elegant, though, such as this solar harvesting blinking gadget.

Like its predecessors, the device itself behaves simply, although this one is equipped with a small supercapacitor which can run the device for 8 hours without sun. It has a small solar panel which can charge the capacitor in five minutes, and from there the LEDs inside simply blink. The quality shows in the final packaging, as [Jasper] has taken to encasing them in epoxy shapes such as pyramids, for a nice paperweight or tchotchke. It is also noteworthy because of Jasper’s test device; since he is mass producing them he needed something to test each board for functionality before encasing them in the epoxy, and he built a small pen tester specifically for them too.

While the build is pretty straightforward, anyone looking to enclose a simple circuit in epoxy without bubbles or other problems might want to check this one out. It would also be a good platform for building other throwie-like projects on top of. In the past they didn’t just blink lights but also did things like run small Linux servers.

This Machine Learning Algorithm Is Meta

September 3, 2019 by Bryan Cockfield 20 Comments

Suppose you ran a website releasing many articles per day about various topics, all following a general theme. And suppose that your website allowed for a comments section for discussion on those topics. Unless you are brand new to the Internet, you’ll also imagine that the comments section needs at least a little bit of moderation to filter out spam, off topic, or even toxic comments. If you don’t want to employ any people for this task, you could try this machine learning algorithm instead.

[Ladvien] goes through a general overview of how to set up a convolutional neural network (CNN) which can be programmed to do many things, but this one crawls a web page, gathers data, and also makes decisions regarding that data. In this case, the task is to identify toxic comments but the goal is not to achieve the sharpest sword in the comment moderator’s armory, but to learn more about how CNNs work.

Written in Python, the process outlines the code itself and how it behaves, setting up a small server to host the neural network, and finally creating the webservice. As with any machine learning, you need a reliable dataset to use for training and this one came from Wikipedia comments previously flagged by humans. Trolling nuance is thrown aside, as the example homes in on blatant insults and vulgarity.

While [Ladvien] notes that his guide isn’t meant to be comprehensive, but rather to fill in some gaps that he noticed within other guides like this, we find this to be an interesting read. He also mentioned that, in theory, this tool could be used to predict the number of comments following an article like this very one based on the language in the article. We’ll leave that one as an academic exercise for now, probably.

Human-Powered Henhouse Keeps Chickens On The Job

September 1, 2019 by Bryan Cockfield 37 Comments

While it’s not exactly in the same vein as other projects around here, like restoring vintage video game systems or tricking an ESP32 to output VGA, keeping chickens can also be a rewarding hobby. They make decent pets and can also provide you with eggs. You can also keep them on a surprisingly small amount of land, but if you have a larger farm you can use them to help condition the soil all over your property. For that you’ll need a mobile henhouse, and as [AtomicZombie] shows, they don’t all have to be towed by a tractor.

This henhouse is human-powered, meaning any regular human can lift it up and scoot it around to different areas without help from heavy equipment. It uses a set of bicycle wheels which rotate around to lift up the frame of the house. A steering wheel in the back allows it to be guided anywhere and then set down. It also has anti-digging protection, which is a must-have for any henhouse to keep the foxes out.

We like this one for its simplicity and ease-of-use. Not needing a tractor on a small farm can be a major cost savings, but if you really need one, [AtomicZombie] also designed a robust all-electric tractor-like device that we featured a little while back.

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Micropython And C Play Together Better

August 31, 2019 by Bryan Cockfield 20 Comments

Python is a versatile, powerful language but sometimes it’s not the best choice, especially if you’re doing work in embedded systems with limited memory. Sometimes you can get away with MicroPython for these cases, but the best language is likely C or assembly. If you’re really stubborn, like [amirgon], and really want C and Python to play well together, you can make use of his new tool which can bring any C library to MicroPython.

As an example of how this tool is used, a “Pure MicroPython” display driver for ILI9341 on the ESP32, which means that everything was implemented in MicroPython. [amirgon] wanted to see how the Python driver would compare to one that’s already been written in C, and use it to showcase MicroPython binding. This tool also automatically converts structs, unions, enums and arrays to Python objects, and provides a means to work with pointers which is something that Python doesn’t handle in the same way that C requires.

[amirgon] hopes that this tool will encourage the adoption of Micropython by removing the obstacle of missing APIs and libraries in MicroPython. Since most libraries for systems like these are written in C, a way to implement them in Python is certainly powerful. We featured one use case for this a while back, but this is a much more generic fix for this coding obstacle.