Is It Time To Retire The TP4056?

The TP4056 is the default charge-controller chip for any maker or hacker working with lithium batteries. And why not? You can get perfectly-functional knockoffs on handy breakout boards from the usual online sources for pennies. Betteridge’s Law aside, [Lefty Maker] thinks that it may well be time to move on from the TP4056 and spends his latest video telling us why, along with promoting an alternative.

His part of choice is another TI chip, the BQ25185. [Lefty] put together his own charge controller board to show off the capabilities of this chip — including variable under- and over-charge protection voltages. Much of his beef with the TP4056 has less to do with that chip than with the cheap charge modules it comes on: when he crows about the lack of mounting holes and proper USB-PD on the knock-off modules, it occurs to us he could have had those features on his board even if he’d used a TP4056.

On the other hand, the flexibility offered by the BQ25185 is great to future-proof projects in case the dominant battery chemistry changes, or you just change your mind about what sort of battery you want to use. Sure, you’d need to swap a few resistors to set new trigger voltages and charging current, but that beats starting from scratch.

[Lefty Maker] also points out some of the advantages to making your own boards rather than relying on cheap modules. Namely, you can make them however you want. From a longer USB port to indicator LEDs and a built-in battery compartment, this charging board is exactly what [Lefty Maker] wants. Given how cheap custom PCBs are these days, it’s not hard to justify rolling your own.

The same cannot be said of genuine TI silicon, however. While the BQ25185 has a few good features that [Lefty Maker] points out in the video, we’re not sure the added price is worth it. Sure, it’s only a couple bucks, but that’s more than a 300% increase!

We’ve seen other projects pushing alternative charge controllers, but for now the TP4056 reigns as the easy option.

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Buying Large LiFePO4 Batteries: How Cheap Is Too Cheap?

It’s a well-known factoid that batteries keep getting cheaper while capacity increases. That said, as with any market that is full of people who are hunting for that ‘great deal’, there are also many shady sellers who will happily sell you a product that could be very dangerous. Especially in the case of large LiFePO4 (LFP) batteries, considering the sheer amount of energy they can contain. Recently [Will Prowse] nabbed such a $125, 100 Ah battery off Amazon that carries no recognizable manufacturer or brand name.

Cheap and cheerful, and probably won't burn down the place. (Credit: Will Prowse, YouTube)
Cheap and cheerful, and probably won’t burn down the place. (Credit: Will Prowse, YouTube)

If this battery works well, it could be an amazing deal for off-grid and solar-powered applications. Running a battery of tests on the battery, [Will] found that the unit’s BMS featured no over-current protection, happily surging to 400 A, with only over-temperature protection keeping it from melting down during a discharge scenario. Interestingly, under-temperature charge protection also worked on the unit.

After a (safe) teardown of the battery the real discoveries began, with a row of missing cells, the other cells being re-sleeved and thus likely salvaged or rejects. Fascinatingly, another YouTuber did a similar test and found that their (even cheaper) unit was of a much lower capacity (88.9 Ah) than [Will]’s with 98 Ah and featured a completely different BMS to boot. Their unit did however feature something of a brand name, though it’s much more likely that these are all just generic LFP batteries that get re-branded by resellers.

What this means is that these LFP batteries may be cheap, but they come with cells that are likely to be of questionable quality, featuring a BMS that plays it fast and loose with safety. Although [Will] doesn’t outright say that you shouldn’t use these batteries, he does recommend that you install a fuse on it to provide some semblance of over-current protection. Keeping a fire extinguisher at hand might also be a good idea.

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A red, cuboid electrochemical cell is in the center of the picture, with a few wires protruding from the front. Tubes run from each side of the cell to a peristaltic pump and tank on each side. The frame holding the pumps and tanks is white 3D printed plastic.

An Open Source Flow Battery

The flow battery is one of the more interesting ideas for grid energy storage – after all, how many batteries combine electron current with fluid current? If you’re interested in trying your hand at building one of these, the scientists behind the Flow Battery Research Collective just released the design and build instructions for a small zinc-iodide flow battery.

The battery consists of a central electrochemical cell, divided into two separated halves, with a reservoir and peristaltic pump on each side to push electrolyte through the cell. The cell uses brass-backed grafoil (compressed graphite sheets) as the current collectors, graphite felt as porous electrodes, and matte photo paper as the separator membrane between the electrolyte chambers. The cell frame itself and the reservoir tanks are 3D printed out of polypropylene for increased chemical resistance, while the supporting frame for the rest of the cell can be printed from any rigid filament.

The cell uses an open source potentiostat to control charge and discharge cycles, and an Arduino to control the peristaltic pumps. The electrolyte itself uses zinc chloride and potassium iodide as the main ingredients. During charge, zinc deposits on the cathode, while iodine and polyhalogen ions form in the anode compartment. During discharge, zinc redissolves in what is now the anode compartment, while the iodine and polyhalogen ions are reduced back to iodides and chlorides. Considering the stains that iodide ions can leave, the researchers do advise testing the cell for leaks with distilled water before filling it with electrolyte.

If you decide to try one of these builds, there’s a forum available to document your progress or ask for advice. This may have the clearest instructions, but it isn’t the only homemade flow cell out there. It’s also possible to make these with very high energy densities.

COTS Components Combine To DIY Solar Power Station

They’re marketed as “Solar Generators” or “Solar Power Stations” but what they are is a nice box with a battery, charge controller, and inverter inside. [DoItYourselfDad] on Youtube decided that since all of those parts are available separately, he could put one together himself.

The project is a nice simple job for a weekend afternoon. (He claims 2 hours.) Because it’s all COTS components, it just a matter of wiring everything together, and sticking into a box.  [DoItYourselfDad] walks his viewers through this process very clearly, including installing a shunt to monitor the battery. (This is the kind of video you could send to your brother-in-law in good conscience.)

Strictly speaking, he didn’t need the shunt, since his fancy LiFePo pack from TimeUSB has one built in with Bluetooth connectivity. Having a dedicated screen is nice, though, as is the ability to charge from wall power or solar, via the two different charge controllers [DoItYourselfDad] includes. If it were our power station, we’d be sure to put in a DC-DC converter for USB-PD functionality, but his use case must be different as he has a 120 V inverter as the only output. That’s the nice thing about doing it yourself, though: you can include all the features you want, and none that you don’t.

We’re not totally sure about his claim that the clear cargo box was chosen because he was inspired by late-90s Macintosh computers, but it’s a perfectly usable case, and the build quality is probably as good as the cheapest options on TEMU.

This project is simple, but it does the job. Have you made a more sophisticated battery box, or other more-impressive project? Don’t cast shade on [DoItYourselfDad]: cast light on your work by letting us know about it!. Continue reading “COTS Components Combine To DIY Solar Power Station”

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

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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Black and white photo of Evertop computer on desk

The Evertop: A Low-Power, Off-Grid Solar Gem

When was the last time you saw a computer actually outlast your weekend trip – and then some? Enter the Evertop, a portable IBM XT emulator powered by an ESP32 that doesn’t just flirt with low power; it basically lives off the grid. Designed by [ericjenott], hacker with a love for old-school computing and survivalist flair, this machine emulates 1980s PCs, runs DOS, Windows 3.0, and even MINIX, and stays powered for hundreds of hours. It has a built-in solar panel and 20,000mAh of battery, basically making it an old-school dream in a new-school shell.

What makes this build truly outstanding – besides the specs – is how it survives with no access to external power. It sports a 5.83-inch e-ink display that consumes zilch when static, hardware switches to cut off unused peripherals (because why waste power on a serial port you’re not using?), and a solar panel that pulls 700mA in full sun. And you guessed it – yes, it can hibernate to disk and resume where you left off. The Evertop is a tribute to 1980s computing, and a serious tool to gain some traction at remote hacker camps.

For the full breakdown, the original post has everything from firmware details to hibernation circuitry. Whether you’re a retro purist or an off-grid prepper, the Evertop deserves a place on your bench. Check out [ericjenott]’s project on Github here.

Handheld 18650 Analyzer Scopes Out Salvaged Cells

You can salvage lithium 18650 cells from all sorts of modern gadgets, from disposable vapes to cordless power tools. The tricky part, other than physically liberating them from whatever they are installed in, is figuring out if they’re worth keeping or not. Just because an 18650 cell takes a charge doesn’t necessarily mean it’s any good — it could have vastly reduced capacity, or fail under heavy load.

If you’re going to take salvaging these cells seriously, you should really invest in a charger that is capable of running some capacity tests against the cell. Or if you’re a bit more adventurous, you can build this “Battery Health Monitor” designed by [DIY GUY Chris]. Although the fact that it can only accept a single cell at a time is certainly a limitation if you’ve got a lot of batteries to go though, the fact that it’s portable and only needs a USB-C connection for power means you can take it with you on your salvaging adventures.

The key to this project is a pair of chips from Texas Instruments. The BQ27441 is a “Fuel Gauge” IC, and is able to determine an 18650’s current capacity, which can be compared to the cell’s original design capacity to come up with an estimate of its overall health. The other chip, the BQ24075, keeps an eye on all the charging parameters to make sure the cell is being topped up safely and efficiently.

With these two purpose-built chips doing a lot of the heavy lifting, it only takes a relatively simple microcontroller to tie them together and provide user feedback. In this case [DIY GUY Chris] has gone with the ATmega328P, with a pair of addressable WS2812B LED bars to show the battery’s health and charge levels. As an added bonus, if you plug the device into your computer, it will output charging statistics over the serial port.

The whole project is released under the MIT license, and everything from the STL files for the 3D printed enclosure to the MCU’s Arduino-flavored firmware is provided. If you’re looking to build one yourself, you can either follow along with the step-by-step assembly instructions, or watch the build video below. Or really treat yourself and do both — you deserve it.

If your battery salvaging operation is too large for a single-cell tester, perhaps it’s time to upgrade to this 40-slot wall mounted unit.

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