Day: November 13, 2019

pierced puffed exposed leads lithium ion battery

Lessons In Li-Ion Safety

November 13, 2019 by 85 Comments

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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Tindie Seller Reviews A Knock-Off Of His Own Product

November 13, 2019 by 66 Comments

If imitation is the sincerest form of flattery, online creators are being sincerely flattered at an alarming rate these days. We Hackaday scribes see it all the time, as straight copy-pastes of our articles turn up on other websites under different bylines. It’s annoying, but given prevailing attitudes toward intellectual property rights, there’s very little point in getting upset about it anymore. But what if it’s hardware that’s being infringed upon?

Hacker and Tindie store proprietor [Brian Lough] recently ran into this problem with one of his products, but rather than get upset, he did a remarkably fair and thoughtful review of the knock-off. The board in question, a D1 Mini Matrix Shield, makes it a snap to use LED matrix panels in projects like his Tetris-themed YouTube sub counter. The knock-off came via Ali Express, with the most “flattering” aspect being the copy and the images on the Ali Express listing, some of which are pulled straight from [Brian]’s Tindie store. While the board’s layout is different, it’s pretty clear that it was strongly inspired by the original. And the changes they did make – like terminal choices and undersizing some traces – only serve to lower the quality of the knock-off. Surely this was a cost-cutting move, so they could undercut sales of the original, right? Apparently not – the knock off is more expensive. Yes, [Brian]’s board is a kit and the imitator is fully assembled, but it still begs the question of why?

Hats off to [Brian] for not only making a useful product, but for taking the time to engineer it properly and having the ambition to put it on the market. It’s a pity that someone felt the need to steal his work, but it seems to be a rite of passage these days.

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Adding Sensors To Improve Your Curling Game? Turns Out It’s Really Hard

November 13, 2019 by 16 Comments

Sometimes, a project turns out to be harder than expected at every turn and the plug gets pulled. That was the case with [Chris Fenton]’s efforts to gain insight into his curling game by adding sensors to monitor the movement of curling stones as well as the broom action. Luckily, [Chris] documented his efforts and provided us all with an opportunity to learn. After all, failure is (or should be) an excellent source of learning.

The first piece of hardware was intended to log curling stone motion and use it as a way to measure the performance of the sweepers. [Chris] wanted to stick a simple sensor brick made from a Teensy 3.0 and IMU to a stone and log all the motion-related data. The concept is straightforward, but in practice it wasn’t nearly as simple. The gyro, which measures angular velocity, did a good job of keeping track of the stone’s spin but the accelerometer was a different story. An accelerometer measures how much something is speeding up or slowing down, but it simply wasn’t able to properly sense the gentle and gradual changes in speed that the stone underwent as the ice ahead of it was swept or not swept. In theory a good idea, but in practice it ended up being the wrong tool for the job.

The other approach [Chris] attempted was to make a curling broom with a handle that lit up differently based on how hard one was sweeping. It wasn’t hard to put an LED strip on a broom and light it up based on a load sensor reading, but what ended up sinking this project was the need to do it in a way that didn’t interfere with the broom’s primary function and purpose. Even a mediocre curler applies extremely high forces to a broom when sweeping in a curling game, so not only do the electronics need to be extremely rugged, but the broom’s shaft needs to be able to withstand considerable force. The ideal shaft would be a clear and hollow plastic holding an LED strip with an attachment for the load sensor, but no plastic was up to the task. [Chris] made an aluminum-reinforced shaft, but even that only barely worked.

We’re glad [Chris] shared his findings, and he said the project deserves a more detailed report. We’re looking forward to that, because failure is a great teacher, and we’ve celebrated its learning potential time and again.