Lessons In Li-Ion Safety

If you came here from an internet search because your battery just blew up and you don’t know how to put out the fire, then use a regular fire extinguisher if it’s plugged in to an outlet, or a fire extinguisher or water if it is not plugged in. Get out if there is a lot of smoke. For everyone else, keep reading.

I recently developed a product that used three 18650 cells. This battery pack had its own overvoltage, undervoltage, and overcurrent protection circuitry. On top of that my design incorporated a PTC fuse, and on top of that I had a current sensing circuit monitored by the microcontroller that controlled the board. When it comes to Li-Ion batteries, you don’t want to mess around. They pack a lot of energy, and if something goes wrong, they can experience thermal runaway, which is another word for blowing up and spreading fire and toxic gasses all over. So how do you take care of them, and what do you do when things go poorly?

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Better Battery Management Through Chemistry

The lead-acid rechargeable battery is a not-quite-modern marvel. Super reliable and easy to use, charging it is just a matter of applying a fixed voltage to it and waiting a while; eventually the battery is charged and stays topped off, and that’s it. Their ease is countered by their size, weight, energy density, and toxic materials.

The lithium battery is the new hotness, but their high energy density means a pretty small package that can get very angry and dangerous when mishandled. Academics have been searching for safer batteries, better charge management systems, and longer lasting battery formulations that can be recharged thousands of times, and a recent publication is generating a lot of excitement about it.

Consider the requirements for a battery cell in an electric car:

  • High energy density (Lots of power stored in a small size)
  • Quick charge ability
  • High discharge ability
  • MANY recharge cycles
  • Low self-discharge
  • Safe

Lithium ion batteries are the best option we have right now, but there are a variety of Li-ion chemistries, and depending on the expected use and balancing and charging, different chemistries can be optimized for different performance characteristics. There’s no perfect battery yet, and conflicting requirements mean that the battery market will likely always have some options.

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Life On Contract: Product Development Lessons Big And Small

Developing a product and getting it out there to build a business is really hard. Whether it’s a single person acting alone to push their passion to the public, or a giant corporation with vast resources, everyone has to go through the same basic steps, and everyone needs to screw those steps up in the same way.

The reality is that the whole process needs to involve lots of aspects in order to succeed; small teams fail by not considering or dedicating resources to all of those aspects, and large teams fail by not having enough communication between the teams working on those pieces. But in truth, it’s a balance of many aspects that unlock a chance at a successful product. It’s worth recognizing this balance and seeking it out in your own product development efforts, whether you’re a one-engineer juggernaut or a large, established company.

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What Happened With Supermicro?

Back in October 2018, a bombshell rocked the tech industry when Bloomberg reported that some motherboards made by Supermicro had malicious components on them that were used to spy or interfere with the operation of the board, and that these motherboards were found on servers used by Amazon and Apple. We covered the event, looking at how it could work if it were true. Now seven months have passed, and it’s time to look at how things shook out.

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Lots Of Blinky! ESP32 Drives 20,000 WS2812 LEDs

20,000 LEDs sounds like an amazing amount of blink. When we start to consider the process of putting together 20,000 of anything, and then controlling them all with a small piece of electronics the size of a postage stamp, we get a little bit dizzy. Continue reading “Lots Of Blinky! ESP32 Drives 20,000 WS2812 LEDs”

Make The Time To Fix Your Time Debt

You’re too busy to read more than this intro paragraph. We all are. Your interest might get piqued enough to skim, but you can’t read the full thing. Our lives all resemble the White Rabbit, constantly late for our next thing, never enjoying the current thing. You feel simultaneously super productive and yet never productive enough to be satisfied. You yearn for a Jarvis that can automate the mundane aspects of your projects, and yet the prospect of building a Jarvis causes anxiety about not having enough time for yet another project. You see another YouTuber showing off not only a great build but also impressive video production and editing skills. You are suffering from Time Debt, and the solution requires as much discipline and tenacity as escaping from financial debt.

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Your Face Is Going Places You May Not Like

Many Chinese cities, among them Ningbo, are investing heavily in AI and facial recognition technology. Uses range from border control — at Shanghai’s international airport and the border crossing with Macau — to the trivial: shaming jaywalkers.

In Ningbo, cameras oversee the intersections, and use facial-recognition to shame offenders by putting their faces up on large displays for all to see, and presumably mutter “tsk-tsk”. So it shocked Dong Mingzhu, the chairwoman of China’s largest air conditioner firm, to see her own face on the wall of shame when she’d done nothing wrong. The AIs had picked up her face off of an ad on a passing bus.

False positives in detecting jaywalkers are mostly harmless and maybe even amusing, for now. But the city of Shenzhen has a deal in the works with cellphone service providers to identify the offenders personally and send them a text message, and eventually a fine, directly to their cell phone. One can imagine this getting Orwellian pretty fast.

Facial recognition has been explored for decades, and it is now reaching a tipping point where the impacts of the technology are starting to have real consequences for people, and not just in the ways dystopian sci-fi has portrayed. Whether it’s racist, inaccurate, or easily spoofed, getting computers to pick out faces correctly has been fraught with problems from the beginning. With more and more companies and governments using it, and having increasing impact on the public, the stakes are getting higher.

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