Save Cells From The Landfill, Get A Power Bank For Your Troubles

April 27, 2025 by Donald Papp 25 Comments

A hefty portable power bank is a handy thing to DIY, but one needs to get their hands on a number of matching lithium-ion cells to make it happen. [Chris Doel] points out an easy solution: salvage them from disposable vapes and build a solid 35-cell power bank. Single use devices? Not on his watch!

[Chris] has made it his mission to build useful things like power banks out of cells harvested from disposable vapes. He finds them — hundreds of them — on the ground or in bins (especially after events like music festivals) but has also found that vape shops are more than happy to hand them over if asked. Extracting usable cells is most of the work, and [Chris] has refined safely doing so into an art.

Disposable vapes are in all shapes and sizes, but cells inside are fairly similar.

Many different vapes use the same cell types on the inside, and once one has 35 identical cells in healthy condition it’s just a matter of using a compatible 3D-printed enclosure with two PCBs to connect the cells, and a pre-made board handles the power bank functionality, including recharging.

We’d like to highlight a few design features that strike us as interesting. One is the three little bendy “wings” that cradle each cell, ensuring cells are centered and held snugly even if they aren’t exactly the right size. Another is the use of spring terminals to avoid the need to solder to individual cells. The PCBs themselves also double as cell balancers, providing a way to passively balance all 35 cells and ensure they are at the same voltage level during initial construction. After the cells are confirmed to be balanced, a solder jumper near each terminal is closed to bypass that functionality for final assembly.

The result is a hefty power bank that can power just about anything, and maybe the best part is that it can be opened and individual cells swapped out as they reach the end of their useful life. With an estimated 260 million disposable vapes thrown in the trash every year in the UK alone, each one containing a rechargeable lithium-ion cell, there’s no shortage of cells for an enterprising hacker willing to put in a bit of work.

Power banks not your thing? [Chris] has also created a DIY e-bike battery using salvaged cells, and that’s a money saver right there.

Learn all about it in the video, embedded below. And if you find yourself curious about what exactly goes on in a lithium-ion battery, let our own Arya Voronova tell you all about it.

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Playing Around With The MH-CD42 Charger Board

December 27, 2024 by Tom Nardi 11 Comments

If you’ve ever worked with adding lithium-ion batteries to one of your projects, you’ve likely spent some quality time with a TP4056. Whether you implemented the circuit yourself, or took the easy way out and picked up one of the dirt cheap modules available online, the battery management IC is simple to work with and gets the job done.

But there’s always room for improvement. In a recent video, [Det] and [Rich] from Learn Electronics Repair go over using a more modern battery management board that’s sold online as the MH-CD42. This board, which is generally based on a clone of the IP5306, seems intended for USB battery banks — but as it so happens, plenty of projects that makers and hardware hackers work on have very similar requirements.

So not only will the MH-CD42 charge your lithium-ion cells when given a nominal USB input voltage (4.5 – 5 VDC), it will also provide essential protections for the battery. That means looking out for short circuits, over-charge, and over-discharge conditions. It can charge at up to 2 A (up from 1 A on the TP4056), and includes a handy LED “battery gauge” on the board. But perhaps best of all for our purposes, it includes the necessary circuitry to boost the output from the battery up to 5 V.

If there’s a downside to this board, it’s that it has an automatic cut-off for when it thinks you’ve finished using it; a feature inherited from its USB battery bank origins. In practice, that means this board might not be the right choice for projects that aren’t drawing more than a hundred milliamps or so.

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Single Crystal Electrode Lithium Ion Batteries Last A Long Time

December 16, 2024 by Al Williams 78 Comments

Researchers have been testing a new type of lithium ion battery that uses single-crystal electrodes. Over several years, they’ve found that the technology could keep 80% of its capacity after 20,000 charge and discharge cycles. For reference, a conventional cell reaches 80% after about 2,400 cycles.

The researchers say that the number of cycles would be equivalent to driving about 8 million kilometers in an electric vehicle. This is within striking distance of having the battery last longer than the other parts of the vehicle. The researchers employed synchrotron x-ray diffraction to study the wear on the electrodes. One interesting result is that after use, the single-crystal electrode showed very little degradation. According to reports, the batteries are already in production and they expect to see them used more often in the near future.

The technology shows promise, too, for other demanding battery applications like grid storage. Of course, better batteries are always welcome, although it is hard to tell which new technologies will catch on and which will be forgotten.

There are many researchers working on making better batteries. Even AI is getting into the act.

Hardware Reuse: The PMG001 Integrated Power Management Module

August 27, 2024 by Dave Rowntree 15 Comments

Battery management is a tedious but necessary problem that becomes more of a hassle with lithium-ion technology. As we’re all very aware, such batteries need a bit of care to be utilized safely, and as such, a huge plethora of ICs are available to perform the relevant duties. Hackaday.IO user [Erik] clearly spent some time dropping down the same old set of ICs to manage a battery in their applications, so they created a drop-in castellated PCB to manage all this.

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Hackaday Links: August 11, 2024

August 11, 2024 by Dan Maloney 8 Comments

“Please say it wasn’t a regex, please say it wasn’t a regex; aww, crap, it was a regex!” That seems to be the conclusion now that Crowdstrike has released a full root-cause analysis of its now-infamous Windows outage that took down 8 million machines with knock-on effects that reverberated through everything from healthcare to airlines. We’ve got to be honest and say that the twelve-page RCA was a little hard to get through, stuffed as it was with enough obfuscatory jargon to turn off even jargon lovers such as us. The gist, though, is that there was a “lack of a specific test for non-wildcard matching criteria,” which pretty much means someone screwed up a regular expression. Outside observers in the developer community have latched onto something more dire, though, as it appears the change that brought down so many machines was never tested on a single machine. That’s a little — OK, a lot — hard to believe, but it seems to be what Crowdstrike is saying. So go ahead and blame the regex, but it sure seems like there were deeper, darker forces at work here.

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Mechanisms of pulse current charging for stabilizing the cycling performance of commercial NMC/graphite LIBs. (Credit: Jia Guo et al., 2024)

Why Pulse Current Charging Lithium-Ion Batteries Extends Their Useful Lifespan

April 16, 2024 by Maya Posch 62 Comments

For as much capacity lithium-ion batteries have, their useful lifespan is generally measured in the hundreds of cycles. This degradation is caused by the electrodes themselves degrading, including the graphite anode in certain battery configurations fracturing. For a few years it’s been known that pulsed current (PC) charging can prevent much of this damage compared to constant current (CC) charging. The mechanism behind this was the subject of a recent research article by [Jia Guo] and colleagues as published in Advanced Energy Materials.

Raman spectra of a) as-cycled and b) surface-removed graphite anodes aged under CC and Pulse-2000 charging. FE-SEM images of the cross-sections of graphite electrodes aged with CC (c,d) and Pulse-2000 (e,f) charging. d,f) are edge-magnified images of (c,e). g) shows the micrograph and O and C element mapping of the surface of CC-aged graphite electrode. TEM images of h) fresh, i) CC, and j) Pulse-2000 aged graphite anodes. (Credit: Jia Guo et al., 2024)

The authors examined the damage to the electrodes after multiple CC and PC cycles using Raman and X-ray absorption spectroscopy along with lifecycle measurements for CC and PC charging at 100 Hz (Pulse-100) and 2 kHz (Pulse-2000). Matching the results from the lifecycle measurements, the electrodes in the Pulse-2000 sample were in a much better state, indicating that the mechanical stress from pulse current charging is far less than that from constant current charging. A higher frequency with the PC shows increased improvements, though as noted by the authors, it’s not known yet at which frequencies diminishing returns will be observed.

The use of PC vs CC is not a new thing, with the state-of-the-art in electric vehicle battery charging technology being covered in a 2020 review article by [Xinrong Huang] and colleagues as published in Energies. A big question with the many different EV PC charging modes is what the optimum charging method is to maximize the useful lifespan of the battery pack. This also applies to lithium-metal batteries, with a 2017 research article by [Zi Li] and colleagues in Science Advances providing a molecular basis for how PC charging suppresses the formation of dendrites .

What this demonstrates quite well is that the battery chemistry itself is an important part, but the way that the cells are charged and discharged can be just as influential, with the 2 kHz PC charging in the research by [Jia Guo] and colleagues demonstrating a doubling of its cycle life over CC charging. Considering the amount of Li-ion batteries being installed in everything from smartphones and toys to cars, having these last double as long would be very beneficial.

Thanks to [Thomas Yoon] for the tip.

Lithium-Ion Batteries Power Your Devboards Easily

March 14, 2024 by Arya Voronova 25 Comments

Last summer, I was hanging out with a friend from Netherlands for a week, and in the middle of that week, we decided to go on a 20 km bike trip to a nearby beach. Problem? We wanted to chat throughout the trip, but the wind noise was loud, and screaming at each other while cycling wouldn’t have been fun. I had some walkie-talkie software in mind, but only a single battery-powered Pi in my possession. So, I went into my workshop room, and half an hour later, walked out with a Pi Zero wrapped in a few cables.

I wish I could tell you that it worked out wonders. The Zero didn’t have enough CPU power, I only had single-core ones spare, and the software I had in mind would start to badly stutter every time we tried to run it in bidirectional mode. But the battery power solution was fantastic. If you need your hack to go mobile, read on.

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