Prototype Sodium Ion Batteries In 18650 Cells

French researchers have announced a prototype of an 18650 sodium-ion battery. If you’ve bought a powerful LED flashlight, a rechargeable battery pack, or a–ahem–stronger than usual LASER pointer, you’ve probably run into 18650 batteries. You often find these inside laptop batteries and –famously– the Tesla electric vehicle runs on a few thousand of these cells. The number might seem like a strange choice, but it maps to the cell size (18 mm in diameter and 65 mm long).

The batteries usually use lithium-ion technology. However, lithium isn’t the only possible choice for rechargeable cells. Lithium has a lot of advantages. It has a high working voltage, and it is lightweight. It does, however, have one major disadvantage: it is a relatively rare element. It is possible to make sodium-ion batteries, although there are some design tradeoffs. But sodium is much more abundant than lithium, which makes up about 0.06% of the Earth’s crust compared to sodium’s 2.6%). Better still, sea water is full of sodium chloride (which we call salt) that you can use to create sodium.

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Maglite 18650 Battery Conversion

maglite 18650

Maglite’s used(?) to be the king of flashlights, but replacing those pesky D-cell batteries is kind of ridiculous in this day and age. So [Travis] decided to upgrade it to make use of the ever-so-common, 18650 lithium-ion battery.

Not looking to purchase any components [Travis] performed this hack using simple recycled household parts. You could solder tabs on the 18650’s so they better mimic a typical alkaline battery cell, but [Travis] notes that because most solder tarnishes the electrical conductivity isn’t always the greatest. So instead, he used aluminum foil. It doesn’t look professional, but it does the job and keeps all the components unmodified so the lithium cells can be used elsewhere if needed. To center the batteries inside the Maglite he used a few strips of cardboard from a case of beer — again, this is just making use of what was available. That being said however, if you wanted to do a professional job on it, nothing is stopping you! A 3D printed 18650 to D-cell adapter would look quite nice… Finally, in order to make the battery spring contact the smaller surface area of the lithium cells, all you have to do is flip it around backwards and slightly bend the inner spring out. That’s about it.

It’s a pretty simple hack we admit, but definitely super handy. In a past project [Travis] also replaced the halogen bulb with a high power LED, making this flashlight even more powerful — and because the LED driver accepts a broader range of voltages it lasts longer too. If you need more inspiration for retrofitting flashlights with LEDs check out this switch-mode driver board hack.

Unfortunately this hack does reduce the Maglite’s thief-head-bashing-ability with such light batteries.

Screenshot of the YouTube channel videos list, showing a number of videos like the ones described in this article.

[DiyOtaku] Gives Old Devices A New Life

Sometimes we get sent a tip that isn’t just a single article or video, but an entire blog or YouTube channel. Today’s channel, [Diy Otaku], is absolutely worth a watch if you want someone see giving a second life to legendary handheld devices, and our creator has been going at it for a while. A common theme in most of the videos so far – taking an old phone or a weathered gaming console, and improving upon them in a meaningful way, whether it’s lovingly restoring them, turning them into a gaming console for your off days, upgrading the battery, or repairing a common fault.

The hacks here are as detailed as they are respectful to the technology they work on. The recent video about putting a laptop touchpad into a game controller, for instance, has the creator caringly replace the controller’s epoxy blob heart with a Pro Micro while preserving the original board for all its graphite-covered pads. The touchpad is the same used in an earlier video to restore a GPD Micro PC with a broken touchpad, a device that you can see our hacker use in a later video running FreeCAD, helping them design a 18650 battery shell for a PSP about to receive a 6000 mAh battery upgrade.

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A cyberdeck/portable PC sits on a deck rail in the sun.

T3rminal Cyberdeck Has Looks To Die For

One of the greatest things about the hacker ecosystem is that whole standing-on-the-shoulders-of-giants thing. Somebody makes something and shares it, and then someone else takes that thing and remixes it, sometimes making it objectively better. For their T3rminal cyberdeck, [calebholloway08] was inspired by a number of projects and came up with something that looks simply fantastic.

Whether you want to call this beauty a cyberdeck or a mobile PC, the guts are what you might expect — a Raspberry Pi 4, an affordable mini keyboard, and a touch screen. But this one took some doing, as in [calebholloway08] had to do a little bit of surgery on the Pi 4, the PiSugar S plus power supply platform, and the display. But you shouldn’t let that stop you from standing on the shoulders of giants, as [calebholloway08] provides (or guides you towards) clear instructions for all three mods.

One thing [calebhollway08] would have done differently was to use something other than a 18650 battery for power, like a 21700. The question is, what will you do differently?

Maybe this is a little too small for you. If so, check out this EMP-protected cyberdeck.

Do You Trust Your Cheap Fuses?

When a fuse is fitted in a power rail, it gives the peace of mind that the circuit is protected. But in the case of some cheap unbranded fuses of the type that come in kits from the usual online suppliers that trust can be illusory, as they fail to meet the required specification.

[Andreas Spiess] has used just these fuses for protection for years as no doubt have many of you, so it was something of a shock for him to discover that sometimes they don’t make the grade. He’s taken a look at the issue for himself, and come up with an accessible way to test your fuses if you have any of those cheap ones.

It’s an interesting journey into the way fuses work, as we’re reminded that the value written on the fuse isn’t the current at which it blows but the maximum it’s intended to take. The specification for fuses should have a graph showing how quickly one should blow at what currents above that level, and the worry was that this time would be simply too long for the cheap ones.

In the video below the break, he looks at the various set-ups required to test a fuse, and instead of a bank of large power supplies, he came up with a circuit involving an 18650 cell and three one ohm resistors in parallel. The resulting 1/3 ohm resistor should pass in the region of 10 A when connected across the 18650, so with a 5 A fuse in that circuit and a storage ‘scope he’s able to quickly test a few candidates. He found that the cheap fuses he had were slower to blow than a Bosch part but weren’t as worrisome as he’d at first thought. If you have any of these parts, maybe you should take a look at them too?

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ESP32 Provides Distraction-Free Writing Experience

Writing out a few thousand words is easy. Getting them in the proper order, now that’s another story entirely. Sometimes you’ll find yourself staring at a blank page, struggling to sieve coherent thoughts from the screaming maelstrom swirling around in your head, for far longer than you’d care to admit. Or so we’ve heard, anyway.

Unfortunately, there’s no cure for writer’s block. But many people find that limiting outside distractions helps to keep the mental gears turning, which is why [Un Kyu Lee] has been working on a series of specialized writing devices. The latest version of the Micro Journal, powered by the ESP32, goes a long way towards achieving his goals of an instant-on electronic notebook.

The writing experience on the Micro Journal is unencumbered by the normal distractions you’d have on a computer or mobile device, as the device literally can’t do anything but take user input and save it as a text file. We suppose you could achieve similar results with a pen and a piece of paper…but where’s the fun in that? These devices are more widely known as writerdecks, which is an extension of the popular cyberdeck concept of hyper-personalized computers.

This newest Micro Journal, which is the fourth iteration of the concept for anyone keeping score, packs a handwired 30% ortholinear keyboard, a 2.8″ ILI9341 240×320 LCD (with SD card slot), ESP32 dev board, and an 18650 battery with associated charging board into a minimalist 3D printed enclosure.

Unable to find any suitable firmware to run on the device, [Un Kyu Lee] has developed his own open source text editor to run on the WiFi-enabled microcontroller. While the distraction-free nature of the Micro Journal naturally means the text editor itself is pretty spartan in terms of features, it does  allow syncing files with Google Drive — making it exceptionally easy to access your distilled brilliance from the comfort of your primary computing device.

While the earlier versions of the Micro Journal were impressive in their own way, we really love the stripped down nature of this ESP32 version. It reminds us a bit of the keezyboost40 and the EdgeProMX, both of which were entered into the 2022 Cyberdeck Contest.

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Ultimate Power: Lithium-Ion Batteries In Series

At some point, the 3.6 V of a single lithium ion battery just won’t do, and you’ll absolutely want to stack LiIon cells in series. When you need high power, you’ve either got to increase voltage or current, and currents above say 10 A require significantly beefed up components. This is how you’re able to charge your laptop from your USB-C powerbank, for instance.

Or maybe you just need higher voltages, and don’t feel like using a step-up converter, which brings along with it some level of inefficiency. Whatever your reasons, it’s time to put some cells into series. Continue reading “Ultimate Power: Lithium-Ion Batteries In Series”