Testing Hundreds Of Used LFP Cells Requires Some Automation

August 4, 2026 by Maya Posch 7 Comments

Although Li-ion cells have become a lot cheaper over the years, if you wish to buy hundreds of high-quality ones for that performance go-kart project, you may feel financially pressured into going for the option of stripping down years-old commercial battery packs instead.

While this is a financially sound option, you do have to figure out what the condition is of each cell before you happily stuff them into a new battery pack for said go-kart, as [Within Tolerance] recently did.

This is something that can be done manually, but for the 768 lithium iron phosphate (LFP) cells that were obtained for this project that’d be quite the tedious task. Hence it was decided to instead spend that time designing a system to automate this process, capable of charging, discharging, measuring and quantifying individual cells.

You can find the resulting Cell Goblin battery tester project on GitHub, which entails a custom PCB featuring an ESP32-S2 as the brains and associated software to monitor the process on a connected PC. Fortunately the issues on the PCB that are described in the video are claimed to be fixed in the repository version.

Using five of these dual-cell cell testers it was possible to run through the hundreds of cells with ten cells at a time. An internal resistance meter was also wired into the PC-based software via its UART. As of publication of the video the testing was still in progress, which gives some idea of how long it takes to work through those cells.

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IBM Home Director: Home Automation In 1996

July 8, 2026 by Maya Posch 20 Comments

Back in the 1990s IBM had a pretty sizeable presence in the PC market, including its rather spiffy Aptiva series of PCs. Naturally their PCs had to feature heavily in another consumer-related thing that was popular in the 1990s, being smart home automation in the form of IBM Home Director. Recently [Ionic1k] took a look at this blast from the past, starting with one of the original IBM commercials.

At its core it used the same X10 protocol that similar solutions from RadioShack and others used, with many modules and packages you could get to use with it. You could also get a more bespoke installation performed at your home to move beyond mere X10, which some people are still finding when they’re buying a house.

Since this uses powerline communication, it required no wires to be run, just the requisite modules to be plugged into a power outlet, with the video demonstrating the basic setup and installation. The PC itself is plugged into the control module via the serial port, from which the Home Director control software can be used to create a configuration and control the state of connected modules.

Although X10 has the same issues as any kind of powerline communication, overall it seems like a very nice system, with a wide range of modules and absolutely easy to set up even for a casual Windows user.

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Home Automation: Simple Vs Easy

June 20, 2026 by Elliot Williams 39 Comments

We’ve been talking a bunch of home automation on the Podcast lately, and this week, in the Mailbag segment, a reader asked us about our setups. Neither Kristina nor I are poster children for the home automation movement: she has absolutely no smart anything because she didn’t want her data up in “the cloud”, and I have an entirely local system that’s really nothing more than a bunch of ad-hoc scripts that talk to an MQTT broker, everything fully DIY but held together with metaphorical duct tape. Neither of us are doing it right, but we’re doing it wrong in interestingly different ways.

Kristina thought, probably because of the range of commercial devices out there that tie you into using their remote data storage services, that giving up control of her data was necessary to use it. And it might be, if you insist that setting up the system be as easy as possible. But the tradeoff for this ease is a drastic reduction in simplicity. You shouldn’t need a remote server in some foreign country to turn your lights on and off. Adding “the cloud” into the mix brings a lot of complexity, mostly in the form of servers that have to be paid for somehow by whatever company is providing the service. It needs to be secure. You might even have to create accounts, remember passwords, and manage that whole deal. Sure, that’s easy enough, but it’s a lot of moving parts, and you can’t blame her for rejecting that complexity.

My system is hosted on a now-ancient OrangePi in the corner, and the network in question is an old WiFi router that it sits on. Nothing needs to leave my four walls, but actually some of it does – I bridge some of the MQTT topics out to an external server for my own amusement. There is no protocol, and no real “system” frankly. Each device in the network has its own topic, and I’m responsible for knowing what it means. The thermometer in the basement has an ESP8266 that transmits on the home/basement/temperature topic, and it puts out its temperature in degrees Celsius. It was the simplest system I could think of, but I have to write whatever software I want to log, display, or act on the data. Of course, that’s simple if you can write some four-liner scripts on the OrangePi broker, but it’s not easy enough that my wife wants to hack on it.

So if the full-buy-in commercial systems are easy but overly complex, and my DIY network is transparently simple but requires a level of hands-on that isn’t easy for “normies”, is there a middle ground? I know half of you are already screaming Home Assistant or Domoticz, and you’re also thinking of which client device libraries you like the most for all your DIY applications: ESPHome vs Tasmota, for instance. And you’re all right!

We are living the in the golden age of the home automation projects. Open-source software and firmware, combined with an abundance of online tutorials and worked examples, have made huge strides toward bridging the gap between simplicity and ease of use. You can set up a hub for everything on a single-board computer, upload the software of your choice, and you don’t need the complexity or loss-of-support liability of a cloud provider. At the same time, setup is easy enough if you’re willing to roll up your sleeves a little bit, and when it’s not, chances are good that someone else has already figured it out for you. These days, interoperability with popular commercial products is shockingly easy to boot.

I need to spend some time and rationalize my system: given the state of the art, it’s simply too simple, and taking a step into an open-source solution would make it easier to use for the rest of the family, without overly complexifying things, adding sketchy dependencies, or losing our data sovereignty. I haven’t finished exploring my options yet, but from what I can see, the community has converged on some goldilocks setups: not too simple or too easy, but rather just right. Thanks, y’all!

DIY, Full-Stack Farm Automation

January 16, 2026 by Bryan Cockfield 13 Comments

Recently, [Vinnie] aka [vinthewrench] moved from Oregon to Arkansas to start a farmstead. This is a style of farming that focuses not just on a profitable farm where produce is sold at market, but also on a homestead where much of one’s own food is grown on the farm as well. Like any farm, though, it’s extremely hard work that takes a tremendous amount of time. Automation and other technology can make a huge impact in these situations, and [Vinnie] is rolling out his own software stack to help with this on his farm.

He calls his project the Pi Internet of Things, or PioT, and as its name suggests is based around the Raspberry Pi. Since this will all be outdoors and exposed to the extremes of Arkansas weather, everything built under the auspices of this project prioritizes ruggedness, stability, and long-term support, all while avoiding any cloud service. The system also focuses on being able to ride through power outages. The server side, called piotserver, uses a REST API to give the user access to the automation systems through a web interface

[Vinnie] also goes into detail about why existing systems like Home Assistant and Open Sprinkler wouldn’t work in his situation, and why a ground-up solution like this is more appropriate for his farm. This post is largely an overview of his system, but some of his other posts go into more detail about things like integrating temperature sensors, rainfall monitoring, controlling irrigation systems, and plenty of other farm automation tasks that are useful for any farmer or gardener.

We’ve also seen some other projects of his here like this project which converts a common AC sprinkler system to an easier-to-use DC system, and a DIY weather station that operates in the 915 MHz band. He’s been a great resource for anyone looking to have technology help them out with their farm or garden, but if you’re just getting started on your green thumb be sure to take a look at this starter guide as well.

HRV Gets Home Automation Upgrades

October 26, 2025 by Bryan Cockfield 6 Comments

In our modern semi-dystopia, it seems like most companies add automation features to their products to lock them down and get consumers to buy even more proprietary, locked-down components. The few things that are still user-upgradable are getting fewer and farther between, but there are still a few things that can be modified and improved to our own liking like this control panel for a heat recovery ventilator (HRV).

HRVs are systems that exchange fresh, outside air with stale, inside air while passing them both through a heat exchanger to keep from wasting energy. Many systems run continuously but they aren’t always needed, so some automation is beneficial. This upgrade from [vincentmakes] improves the default display for a Zehnder Comfoair Q350 HRV with a color display as well as adding it in to a home automation system, letting a user control fan speeds remotely as well as alerting the user when it’s time for filter replacements and providing up-to-date information from all the sensors in the HRV.

The project builds on a previous project which adapted an ESP32 to interact with the CAN bus used on these devices. With these upgrades the user can forgo the $300 proprietary upgrade that would be needed to get the same functionality otherwise. It’s also fully open-source so all that’s needed is to flash the firmware, replace the display, and enjoy the fresh air. There’s other modern HVAC equipment that can benefit from new controllers and a bit of automation as well.

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“Unnecessary” Automation Of A DIY Star Lamp Build

March 23, 2025 by Elliot Williams 10 Comments

It all started with a gift idea: a star-field lamp in the form of a concrete sphere with lightpipes poking out where the stars are, lit up from the inside by LEDs. When you’re making one of these, maybe-just-maybe you’d be willing to drill a thousand holes and fit a thousand little plastic rods, but by the time you’re making a second, it’s time to build a machine to do the work for you.

So maybe we quibble with the channel name “Unnecessary Automation,” but we won’t quibble with the results. It’s a machine that orients a sphere, drills the hole, inserts the plastic wire, glues it together with a UV-curing glue, and then trims the end off. And if you like crazy machines, it’s a beauty.

The video goes through all of the design thoughts in detail, but it’s when it comes time to build the machine that the extra-clever bits emerge. For instance, [UA] used a custom 3D-printed peristaltic pump to push the glue out. Taking the disadvantage of peristaltic pumps – that they pulse – as an advantage, a custom housing was designed that dispensed the right amount between the rollers. The rolling glue dispenser mechanism tips up and back to prevent drips.

There are tons of other project-specific hacks here, from the form on the inside of the sphere that simplifies optic bundling and routing to the clever use of a razor blade as a spring. Give it a watch if you find yourself designing your own wacky machines. We think Rube Goldberg would approve. Check out this video for a more software-orientated take on fiber-optic displays.

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Adding Human Detection To Home Automation

August 29, 2024 by Bryan Cockfield 39 Comments

Radar made a huge impact when it was first invented, allowing objects to be detected using radio waves which would normally be difficult or impossible to observe through other means. Radio waves of all frequencies can be used for radar as well, whether that’s detecting ships beyond the horizon, tracking aircraft near an airport, penetrating the ground, or imaging objects with a high resolution. At the millimeter wavelength it’s fairly easy to detect humans with the right hardware, and using some inexpensive radar modules [Tech Dregs] shows us how to add this capability a home automation system.

Since these modules aren’t trying to image humans with fine detail or detect them at long range, the hardware can be fairly inexpensive. [Tech Dregs] is using the LD2410B modules which have not only an on-board microcontroller but also have the radio antennas used for radar built right onto the PCB. They have a simple binary output which can communicate whether or not a human is detected, but there’s also UART for communicating more details about what the module senses in the room. [Tech Dregs] is using this mode to connect the modules to Home Assistant, where they will be used to help automate his home’s lighting.

The only significant problem he had setting these modules up was getting them built into an enclosure. The short wavelengths used in this type of radar module don’t penetrate solid objects very well at all, so after trying to hide one behind an e-ink screen he eventually settled on hollowing out a space in a bezel with very thin plastic between the module and the room. If you need more out of your radar modules than object detection, though, you can always try building a pulse compression radar which can provide much more accurate ranging of objects.

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