Lumafield battery quality report cover page

Lumafield Peers Into The 18650 Battery

January 31, 2026 by John Elliot V 21 Comments

[Alex Hao] and [Andreas Bastian] of Lumafield recently visited with [Adam Savage] to document their findings after performing X-ray computed tomography scans on over 1,000 18650 lithium-ion batteries.

The short version — don’t buy cheap cells! The cheaper brands were found to have higher levels of manufacturing defects which can lead them to being unsafe. All the nitty-gritty details are available in the report, which can be downloaded for free from Lumafield, as well as the Tested video they did with [Adam] below.

Actually we’ve been talking here at Hackaday over at our virtual water-cooler (okay, okay, our Discord server) about how to store lithium-ion batteries and we learned about this cool bit of kit: the BAT-SAFE. Maybe check that out if you’re stickler for safety like us! (Thanks Maya Posch!)

We have of course heard from [Adam Savage] before, check out [Adam Savage] Giving A Speech About The Maker Movement and [Adam Savage]’s First Order Of Retrievability Tool Boxes.

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Hackaday Podcast Episode 355: Person Detectors, Walkie Talkies, Open Smartphones, And A WiFi Traffic Light

January 30, 2026 by Jenny List No comments

Another chilly evening in Western Europe, as Elliot Williams is joined this week by Jenny List to chew the fat over the week’s hacks.

It’s been an auspicious week for anniversaries, with the hundredth since the first demonstration of a working television system in a room above a London coffee shop. John Logie Baird’s mechanically-scanned TV may have ultimately been a dead-end superseded by the all-electronic systems we all know, but the importance of television for the later half of the 20th century and further is beyond question.

The standout hacks of the week include a very clever use of the ESP32’s WiFi API to detect people moving through a WiFi field, a promising open-source smartphone, another ESP32 project in a comms system for cyclists, more cycling on tensegrity spokes, a clever way to smooth plaster casts, and a light sculpture reflecting Wi-Fi traffic. Then there are a slew of hacks including 3D printed PCBs and gem-cut dichroic prisms, before we move to the can’t-miss articles. There we’re looking at document preservation, and a wallow in internet history with a look at the Netscape brand.

As usual all the links you need can be found below, so listen, and enjoy!

Or download the podcast old-school, with a direct link to the MP3 file in question.

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Hackaday Links: January 25, 2026

January 25, 2026 by Tom Nardi 3 Comments

If predictions hold steady, nearly half of the United States will be covered in snow by the time this post goes live, with the Northeast potentially getting buried under more than 18 inches. According to the National Weather Service, the “unusually expansive and long-duration winter storm will bring heavy snow from the central U.S. across the Midwest, Ohio Valley, and through the northeastern U.S. for the remainder of the weekend into Monday.” If that sounds like a fun snow day, they go on to clarify that “crippling to locally catastrophic impacts can be expected”, so keep that in mind. Hopefully you didn’t have any travel plans, as CNBC reported that more than 13,000 flights were canceled as of Friday night. If you’re looking to keep up with the latest developments, we recently came across StormWatch (GitHub repo), a slick open source weather dashboard that’s written entirely in HTML. Stay safe out there, hackers.

Speaking of travel, did you hear about Sebastian Heyneman’s Bogus Journey to Davos? The entrepreneur (or “Tech Bro” to use the parlance of our times) was in town to woo investors attending the World Economic Forum, but ended up spending the night in a Swiss jail cell because the authorities thought he might be a spy. Apparently he had brought along a prototype for the anti-fraud device he was hawking, and mistakenly left it laying on a table while he was rubbing shoulders. It was picked up by security guards and found to contain a very spooky ESP32 development board, so naturally he was whisked off for interrogation. A search of his hotel room uncovered more suspicious equipment, including an electric screwdriver and a soldering iron. Imagine if a child had gotten their hands on them?

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Hackaday Podcast Episode 354: Firearms, Sky Driving, And Dumpster Diving

January 23, 2026 by Al Williams 1 Comment

Hackaday Editors Elliot Williams and Al Williams took a break to talk about their favorite hacks last week. You can drop in to hear about articulated mirrors, triacs, and even continuous 3D-printing modifications.

Flying on an airplane this weekend? Maybe wait until you get back to read about how the air traffic control works. Back home, you can order a pizza on a Wii or run classic Basic games on a calculator.

For the can’t miss articles, the guys talked about very low Earth orbit satellites and talked about readers who dumpster dive.

Check out the links below if you want to follow along, and don’t be shy. Tell us what you think about this episode in the comments!

As always, this episode is available in DRM-free MP3.

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The Shelly 2.5 Smart Relay Design Flaw Killing Capacitors

January 17, 2026 by Maya Posch 32 Comments

Part of any self-respecting Smart Home, smart relays are useful for switching and monitoring loads that do not plug into an outlet. This also makes them a lot more integrated, and thus, a long lifespan is very welcome. Unfortunately, the popular Shelly 2.5 smart relays seem to be having a bit of a design flaw as they’re dying in droves once their 2-year warranty period is up. The cause and repair are covered in a recent [VoltLog] video on YouTube.

As noted in the Shelly documentation for the device, it’s a very compact form factor device, with screw terminals, two relays, and three fairly large electrolytic capacitors sharing very little space with the rest of the components. The apparent flaw comes in the form of these capacitors failing, with the video showing that one 100 µF capacitor has a massively increased ESR, likely due to electrolyte venting. This results in the observed symptoms, such as WiFi connectivity issues and audible hissing, the latter of which is demonstrated in the video.

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How Accurate Is A 125 Year Old Resistance Standard?

January 16, 2026 by Maya Posch 43 Comments

Internals of the 1900 Evershed & Vignoles Ltd 1 ohm resistance standard. (Credit: Three-phase, YouTube)

Resistance standards are incredibly useful, but like so many precision references they require regular calibration, maintenance and certification to ensure that they stay within their datasheet tolerances. This raises the question of how well a resistance standard from the year 1900 performs after 125 years, without the benefits of modern modern engineering and standards. Cue the [Three-phase] YouTube channel testing a genuine Evershed & Vignoles Ltd one ohm resistance standard from 1900.

With mahogany construction and brass contacts it sure looks stylish, though the unit was missing the shorting pin that goes in between the two sides. This was a common feature of e.g. resistance decade boxes of the era, where you inserted pins to connect resistors until you hit the desired total. Inside the one ohm standard is a platinoid resistor, which is an alloy of copper, nickel, tungsten, and zinc. Based on the broad arrow mark on the bottom this unit was apparently owned by the UK’s Ordnance Board, which was part of what was then called the War Office.

After a quick gander at the internals, the standard was hooked up to a Keithley DMM7510 digital bench meter. The resistance standard’s ‘datasheet’ is listed on top of the unit on the brass plaques, including the effect of temperature on its accuracy. Adjusting for this, the measured ~1.016 Ω was within 1.6% tolerance, with as sidenote that this was with the unit not having been cleaned or otherwise having had maintenance performed on it since it was last used in service. Definitely not a bad feat.

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Hackaday Podcast Episode 353: Fantastic Peripherals, Fake Or Not Fake Picos, And Everything On The Steam Deck

January 16, 2026 by Tom Nardi 2 Comments

Join Hackaday Editors Elliot Williams and Tom Nardi as they swap their favorite hacks and stories from the week. In this episode, they’ll start off by marveling over the evolution of the “smart knob” and other open hardware input devices, then discuss a futuristic propulsion technology you can demo in your own kitchen sink, and a cheap handheld game system that get’s a new lease on life thanks to the latest version of the ESP32 microcontroller.

From there they’ll cover spinning CRTs, creating custom GUIs on Android, and yet another thing you can build of out that old Ender 3 collecting dust in the basement. The episode wraps up with a discussion about putting Valve’s Steam Deck to work and a look at the history-making medical evacuation of the International Space Station.

Check out the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

As always, this episode is available in DRM-free MP3.