Calendar aging of NMC Li-ion cells at 50 ℃ at various SoCs. (Credit: Wiljan Vermeer, IEEE, 2021)
With batteries being such an integral part of smartphones, it’s little wonder that extending the period between charging and battery replacement has led to many theories and outright myths about what may affect the lifespan of these lithium-ion batteries. To bust some of them, [HTX Studio] over on YouTube has spent the past two years torturing both themselves and a myriad of both iOS and Android phones to tease out some real-life data.
After a few false starts with smaller experiments, they settled on an experimental setup involving 40 phones to investigate two claims: first, whether fast charging is worse than slow charging, and second, whether limiting charging to 80% of a battery’s capacity will increase its lifespan. This latter group effectively uses only 50% of the capacity, by discharging down to 30% before recharging. A single control phone was left alone without forced charge-discharge cycles.
A while back [Clint Basinger] of Lazy Game Reviews fame purchased a rare 1980s Halikan laptop. When he received the parcel, at first glance, everything seemed in order. Upon opening the original laptop bag, however, it was found that the combination of the heavy power supply in a side pocket and the brittle plastic of the laptop’s case had turned the latter into sad fragments of regret. At the time [Clint] wasn’t sure what he’d do, but fortunately [polymatt] stepped in with the joyful news: we can rebuild it; we have the technology.
Obviously, the sad plastic fragments of the original case weren’t going together again in any meaningful way, nor would this have been helpful, but the pieces, along with photos of an intact laptop, helped with the modelling of a digital model of the case. One model and one 3D printer is all you need. For this case, the print used ABS, with gaps between the segmented prints filled with an ABS slurry, as the case was too large to be printed without jumping through some hoops.
The eccentric shaft and rotor of the Mazda 12A rotary engine. (Credit: Baked Beans Garage, YouTube)
In theory, Wankel-style rotary internal combustion engines have many advantages: they ditch the cumbersome crankcase and piston design, replacing it with a simple, single-chamber design and a thick, plectrum-shaped chunk of metal that spins around inside that chamber to create virtual combustion chambers. This saves weight and maximizes performance-to-weight. Unfortunately, these types of engines are also known for burning a lot of oil and endless seal troubles, especially with early rotary Mazda engines that easily died.
Yet even 1980 versions were not without issues, a case in point is the Mazda 1st gen RX7 with a 12A rotary engine that the [Baked Beans Garage] over at YouTube got their paws on. Starting with unsuccessful attempts to make the car start, the next step was to roll the car into the morgue garage for a full teardown of the clearly deceased engine.
About 35 minutes into the video, we get to the teardown of the engine, with its parts contrasted with those of a newer revision rotary engines alongside illustrations of their functioning, making it as much an autopsy as a detailed introduction to these rotary engines. Technically, they also aren’t the original DKM-style Wankel engines, but a KKM-style engine, as designed by [Hanns-Dieter Paschke]. [Wankel] didn’t like the eccentric KKM design, as he thought it’d put too much stress on the apex seals, but ultimately the more economical KKM design was further developed.
During the autopsy of the 12A revision Mazda engine, it becomes clear that it was likely overheating that killed the engine over the course of years of abuse, along with ‘chatter’ marks of the apex seals destroying the inner chrome coating. This would have compromised compression and with it any chance of the engine running, not unlike a piston engine with badly scored cylinder walls after ingesting some metal chunks.
While the Mazda 12B and subsequent designs addressed many of the issues with the early rotary engines, its use was limited to some sports models, ending in 2012 with the RX-8. The currently produced Mazda MX-30 does use a rotary engine again in its plug-in hybrid version, but it’s only as a range extender engine that drives a generator. Looking at the internals of those Mazda rotary engines, it’s easy to see how complex they are to keep running, but you cannot help but feel a little bit of sadness that these small-but-powerful engines didn’t make much more of a splash.
Finding older versions of particular software can be a real chore, all too often only made possible by the sheer grace and benevolence of their creators. At the same time older versions of software can be the only way to dodge undesirable ‘upgrades’, track down regressions, do historical research, set up a retro computer system, and so on. This is where an archive like OldVersion.com (HTTP only so your browser may shout at you) is incredibly useful, offering thousands of installers for software covering a number of platforms.
Unfortunately, as noted on the website, they recently lost their main source of income in the form of Google advertising. This means that after launching in 2001, this archive may soon have to be shut down before long. Confusingly, trying to visit the blog throws a HTTP 503 error, and visiting the forum currently forces a redirect to a random news site unless you can mash that Esc button really fast, perhaps as alternative advertising partners are being trialed, or due to a hack.
Although these days we have sites like Archive.org to do more large scale archiving, OldVersion.com is special for being focused and well-organized, along with a long and rich history that would be a shame to lose. We have referenced the site in the past for old versions as far back as 2008. Hopefully we’ll soon find out more about what is going on with the archive and what its future will be.
Over the decades we have seen a lot of methods for powering LEGO-based contraptions, ranging from LEGO Technic pneumatics to electric motors, but what about steam power? We have all seen those cute little model steam engines that can definitely put out some power. Sure, you can just drop those in like a kind of confused internal combustion engine, or you can try to make a steam engine that actually tries to be directly compatible with LEGO.
While exploring this topic, [Jamie’s Brick Jams] on YouTube found that the primary concern here is simply the very hot steam produced by the boiler. While not a surprise to anyone who has ever run a model steam engine, this poses a major challenge to the thermoplastics used by LEGO.
Obviously a boiler cannot be made out of plastic, but the steam turbine can. That said, material selection here is key, as the hot, wet steam produced by the boiler demolishes PLA parts and ruined the original and very unsafe copper boiler in the process. Ultimately a LEGO Technic-compatible steam turbine was printed in high temperature resistant PAHT-CF and PC filament, which enables a steam-powered LEGO walker to come to life, albeit with a distinct lack of power.
Model steam engine enthusiasts are of course quick to point out that you should try to create dry steam through superheating, definitely add a safety valve and so on, all of which should make for an even more powerful and safe LEGO steam engine. For a rundown of how steam engines work, [Lawrie] did an excellent video on the basics a while back, as well as a video playlist full of demonstrations of both classical Mamod model engines and questionable modern takes.
Suffice it to say that although model steam engines look like toys, they involve fire, hot steam and other fascinating ways to melt things, light them on fire and cause painful injuries, so definitely follow a safety briefing before attempting any of it at home.
When you hear it said that “Modern steel is disposable by design”, your ears perk up, as you just caught the unmistakable sound of faux romanticism along with ‘lost ancient technology‘ vibes. Although it happens sometimes that we did lose something important, as with for example the ancient Roman concrete that turns out to have self-healing properties as a result of so-called hot mixing, this is decidedly an exception.
We nearly lost that technology because of the technological and scientific bonfire that was the prelude to a thousand years of darkness over Europe: called the Dark Ages, Middle Ages as well as the medieval period. Thus when you come across a slideshow video with synthesized monotonal voice-over which makes the bold claim that somehow medieval iron was superior and today’s metallurgy both worse and designed to break, you really have to do a spit-take. The many corrections in the comment section further reinforces the feeling that it’s more slop than fact.
One of the claims made is that the bloomery furnace beats the blast furnace, due to beneficial additives to the iron. Considering that the video cites its sources, it’s at least worthy of a dive into the actual science here. Are modern iron and steel truly that inferior and disposable?
When you go on your favorite cheap online shopping platform and order a batch of 74LS logic ICs, what do you get? Most likely relabeled 74HC ICs, if the results of an AliExpress order by [More Fun Fixing It] on YouTube are anything to judge by. Despite the claims made by the somewhat suspect markings on the ICs, even the cheap component tester used immediately identified them as 74HC parts.
Why is this a problem, you might ask? Simply put, 74LS are Low-power Schottky chips using TTL logic levels, whereas 74HC are High-Speed CMOS, using CMOS logic levels. If these faked chips had used 74HCT, they would have been compatible with TTL logic levels, but with the TTL vs CMOS levels mismatch of 74HC, you are asking for trouble.
CMOS typically requires that high levels are at least 70% of Vcc, and low to be at most 30% of Vcc, whereas TTL high level is somewhere above 2.0V. 74HC also cannot drive its outputs as strongly as 74LS, which opens another can of potential issues. Meanwhile HCT can be substituted for LS, but with the same lower drive current, which may or may not be an issue.
Interestingly, when the AliExpress seller was contacted with these findings, a refund was issued practically immediately. This makes one wonder why exactly faked 74LS ICs are even being sold, when they’d most likely be stuffed into old home computers by presumably hardware enthusiasts with a modicum of skill and knowledge.
