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Battery Management Module Hacked for Lithium-Iron Battery Bank

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In a departure from his usual repair and tear down fare, [Kerry Wong] has set out on a long-term project — building a whole-house battery bank. From the first look at the project, this will be one to watch.

To be fair, [Kerry] gave us a tease at this project a few months back with his DIY spot welder for battery tabs. Since then, he appears to have made a few crucial design decisions, not least of which is battery chemistry. Most battery banks designed for an inverter with enough power to run household appliances rely on lead-acid batteries, although lithium-ion has certainly made some inroads. [Kerry] is looking to run a fairly small 1000-watt inverter, and his analysis led him to lithium-iron cells. The video below shows what happens when an eBay pack of 80 32650 LiFePo4 cells meets his spot welder. But then the problem becomes one of sourcing a battery management system that’s up to the charge and discharge specs of his 4s battery pack. We won’t spoil the surprise for you, but suffice it to say that [Kerry] really lucked out that only minimal modifications were needed for his $9 off-the-shelf BMS module.

We’re looking forward to seeing where this build goes, not least because we’d like to build something similar too. For a more traditional AGM-based battery bank, check out this nicely-engineered solar-charged system.


Filed under: home hacks, misc hacks

Lithium Ion Versus LiPoly In An Aeronautical Context

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When it comes to lithium batteries, you basically have two types. LiPoly batteries usually come in pouches wrapped in heat shrink, whereas lithium ion cells are best represented by the ubiquitous cylindrical 18650 cells. Are there exceptions? Yes. Is that nomenclature technically correct? No, LiPoly cells are technically, ‘lithium ion polymer cells’, but we’ll just ignore the ‘ion’ in that name for now.

Lithium ion cells are found in millions of ground-based modes of transportation, and LiPoly cells are the standard for drones and RC aircraft. [Tom Stanton] wondered why that was, so he decided to test the energy density per mass of these battery chemistries, and what he found was very interesting.

The goal of [Tom]’s experiment was to test LiPoly against lithium ion batteries in the context of a remote-controlled aircraft. Since weight is what determines flight time, cutting even a few grams from an airframe can vastly extend the capabilities of an aircraft. The test articles for this experiment come in the form of a standard 1800 mAh LiPoly battery and four 18650 cells wired together as a 3000 mAh battery. Here’s where things get interesting: the LiPoly battery weighs 216 grams for an energy density of 0.14 Watt-hours per gram. The lithium ion battery weighs 202 grams for an energy density of 0.25 Watt-hours per gram. If you just look at the math, all drones are doing it wrong. 18650 cells appear to have a much higher energy density per mass than the usual LiPoly cells. How does that hold up in a real-world test, though?

Using his neat plane with 3D printed wing ribs as the testbed, [Tom] plugged in the batteries and flew around a field for the better part of an afternoon. The LiPo flew for 41.5 minutes, whereas the much more energy dense lithium ion battery flew for 36.5 minutes. What’s going on here?

While the lithium ion battery has a much higher capacity, the problem here is the internal resistance of each battery chemistry. The end voltage for the LiPo was a bit lower than the lithium ion battery, suggesting the 18650 cells can be run down a bit further than [Tom]’s test protocol allowed. After recharging each of these batteries and doing a bit of math, [Tom] found the lithium ion batteries can fly for about twice as long as their LiPo counterparts. That means an incredibly long test of flying a plane in a circle over a field; not fun, but we are looking forward to other people replicating this experiment.


Filed under: drone hacks

Cordless Tool Battery Pack Turned into Portable Bench Supply

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Say what you want about the current crop of mass-marketed consumer-grade cordless tools, but they’ve got one thing going for them — they’re cheap. Cheap enough, in fact, that they offer a lot of hacking opportunities, like this portable bench power supply that rides atop a Ryobi battery.

Like many of the more common bench supply builds we’ve seen,  [Pat K]’s more portable project relies on the ubiquitous DPS5005 power supply module, obtained from the usual sources. [Pat K] doesn’t get into specifics on performance, but supplied with 18 volts from a Ryobi One+ battery, the DC-DC programmable module should be able to do up to about 16 volts. Mating the battery to the supply is easy with the 3D-printed case, which has a socket for the battery that mimics the sockets on tools from the Ryobi line. It’s simple and effective, as well as neatly executed. The files for the case are on Thingiverse; sadly, only an STL file is included, so if you want to support another brand’s batteries, you’ll have to roll your own.

Check out some of the other power supplies we’ve featured that use the DPS5005 and its cousins, like this nice bench unit. We’ve also covered some of the more hackable aspects of this module, such as an open-source firmware replacement.

Comparing Making To Buying A Lithium Ion Battery Pack

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At Hackaday we’re all about DIY. However, projects can have many components, and so there’s sometimes a choice between making something or buying it. In this case, [GreatScott!] wondered if it would be cheaper to make or buy a lithium-ion battery pack for his new eBike kit. To find out, he decided to make one.

After some calculations, he found he’d need thirteen 18650 cells in series but decided to double the capacity by connecting another thirteen in parallel. That gave him a 5 Ah capacity battery pack with a nominal voltage of 48.1 V and one capable of supplying a constant current of 40 A. Rather than connect them by soldering the nickel strips, he purchased a kWeld battery spot welder, adding to the cost of the build. He charged his new battery pack using his bench power supply but being concerned about uneven charging of the cells over the battery pack’s lifetime, he added a Battery Management System (BMS). The resulting battery pack powers his eBike motor just fine.

After adding up all the costs, he found it was only a tiny bit cheaper than prices for comparable battery packs on eBay, which were €24.4 per Ah (US$29.5 per Ah). The only way it would be cheaper is if he made multiple packs, spreading out the one-time cost of the battery spot welder. So that means it’s really up to your preference. See his video below to judge for yourself if you’d rather do it the DIY way. And then let us know what you’d do in the comments below.

If it’s the battery controller you’re interested in then check out this journey taken when a hacker ran into a controller which refused to charge its batteries.

 

[GreatScott] Tests His DIY Battery Pack On His E-Bike

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[GreatScott] has now joined the ranks of Electric Bike users. Or has he? We previously covered how he made his own lithium-ion battery pack to see if doing so would be cheaper than buying a commercially made one. But while it powered his E-bike conversion kit on his benchtop, turning the motor while the wheel was mounted in a vice, that’s no substitution for a real-world test with him on a bike on the road.

Since then he’s designed and 3D printed an enclosure for his DIY battery pack and mounted it on his bike along with most of the rest of his E-bike kit. He couldn’t use the kit’s brake levers since his existing brake levers and gear-shift system share an enclosure. There also weren’t enough instructions in the kit for him to mount the pedal assistance system. But he had enough to do some road testing.

Based on a GPS tracker app on his phone, his top speed was 43 km/h (27 miles per hour). His DIY 5 Ah battery pack was half full after 5 km (3.1 miles) and he was able to ride 11.75 km (7.3 miles) on a single charge. So, success! The battery pack did the job and if he needs to go further then he can build a bigger pack with some idea of how it would improve his travel distance.

Sadly though, he had to remove it all from his bike since he lives in Germany and European rules state that for it to be considered an electric bike, it must be pedal assisted and the speed must the be progressively reduced as it reaches a cut-off speed of 25 km/h (15 miles per hour). In other words, his E-bike was more like a moped or small motorcycle. But it did offer him some good opportunities for hacking, and that’s often enough. Check out his final assembly and testing in the video below.

And there is plenty of room for hacking with E-bikes. This one, for example, forgoes the kit route and is done from scratch and includes a dashboard.

An E-Bike Battery Pack Without Spot Welding

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In somewhat of a departure from their normal fare of heavy metal mods, [Make It Extreme] is working on a battery pack for an e-bike that has some interesting design features.

The guts of the pack are pretty much what you’d expect – recovered 18650 lithium-ion cells. They don’t go into details, but we assume the 52 cells were tested and any duds rejected. The arrangement is 13S4P, and the cells are held in place with laser-cut acrylic frames. Rather than spot weld the terminals, [Make It Extreme] used a series of strategically positioned slots to make contacts from folded bits of nickel strip. Solid contact is maintained by cap screws passing between the upper and lower contact frames. A forest of wires connects each cell to one of four BMS boards, and the whole thing is wrapped in a snappy acrylic frame. The build and a simple test are in the video below.

While we like the simplicity of a weld-less design, we wonder how the pack will stand up to vibration with just friction holding the cells in contact. Given their previous electric transportation builds, like this off-road hoverbike, we expect the pack will be put to the test soon, and in extreme fashion.

Getting the Lead Out of Lithium Battery Recycling

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When that fateful morning comes that your car no longer roars to life with a quick twist of the key, but rather groans its displeasure at the sad state of your ride’s electrical system, your course is clear: you need a new battery. Whether you do it yourself or – perish the thought – farm out the job to someone else, the end result is the same. You get a spanking new lead-acid battery, and the old one is whisked away to be ground up and turned into a new battery in a nearly perfect closed loop system.

Contrast this to what happens to the battery in your laptop when it finally gives up the ghost. Some of us will pop the pack open, find the likely one bad cell, and either fix the pack or repurpose the good cells. But most dead lithium-based battery packs are dropped in the regular trash, or placed in blue recycling bins with the best of intentions but generally end up in the landfill anyway.

Why the difference between lead and lithium batteries? What about these two seemingly similar technologies dictates why one battery can have 98% of its material recycled, while the other is cheaper to just toss? And what are the implications down the road, when battery packs from electric vehicles start to enter the waste stream in bulk?

Time + Chemistry = Economics

Understanding the disparity between lead-acid and lithium-ion battery recycling boils down to two major factors: time and chemistry. On the time side of the equation, consider that the big chunky battery under your hood is pretty old technology. Lead-acid batteries have been around for as long as cars have, and then some. As such, they have over a century’s head start on their lithium based cousins in terms of infrastructure. We’ve been using these things forever, and we’ve really dialed in their lifecycle management. From cradle to grave and back to cradle again, lead-acid batteries benefit from an extensive and highly integrated manufacturing and distribution system, one that the lithium-ion industry just has not yet had time to develop. The lead-acid infrastructure goes so far as to often use the exact same trucks that deliver batteries to retailers for the return trip to the recycler.

Time also plays into it via the rapid turnover of automotive batteries. The average car battery lasts about four years, give or take, and since the average lifetime of a car is now about eleven years, each car will likely see three or more batteries over its service life. For electric vehicles and hybrids, the battery pack is designed to last for pretty much the service life of the vehicle, so barring accidents that render the vehicle wrapped around them useless, lithium-ion packs are just not going to enter into the recycling stream nearly as often as lead-acid batteries do. This is somewhat negated by the number of lithium-ion battery packs from consumer products like laptops and power tools; those enter the waste stream far faster than lithium-ion batteries from electric and hybrid vehicles. But those numbers are a rounding error in the equation compared to the number of lead-acid batteries recycled every day.

Lead-acid batteries can be nearly 100% recycled. Source: US Green Technology

As for chemistry, the simpler the mix of materials in an object, the easier it is to recycle. Aluminum cans, which are just aluminum and paint, are incredibly easy to reclaim with the addition of a little heat. Lead-acid batteries are not quite that simple, but they’re close: just lead, lead oxide, and sulfuric acid in a plastic case. Each material in the battery has a simple path from old to new: the lead plates melt easily at low temperatures and can be easily purified, ditto for the PVC that typically makes up the battery’s case, and the sulfuric acid electrolyte can either be diluted and disposed of as wastewater, or the sulfates can be recovered to manufacture new electrolytes or used in the production of other consumer items, such as soaps.

Lithium batteries, on the other hand, have much more complicated chemistries and a mix of materials that don’t work and play well together in an industrial recycling process. A lithium-ion battery is not just lithium but also has cobalt, manganese, iron phosphate, or nickel compounds, not to mention aluminum, copper, and graphite. Not only is the mix of metals more complicated, but their physical form as powders coated onto metal foil makes recovery of each component far more complicated than just throwing it in a furnace.

The electrolyte in a lithium battery is much more complicated too, consisting of lithium salts in volatile organic solvents like ethylene carbonate. This makes the liberated electrolytes much more difficult to deal with as well; no simple dilution and neutralization with a basic solution like sodium bicarbonate will render these compounds safe enough to discharge to a sewer as is the case for lead-acid recycling. Dealing with that adds to the cost of recycling and cuts into the potential profit.

A Hands-Off Process

The mechanical process of recycling is also much easier for lead-acid batteries. In the most advanced recycling plants, used car batteries can literally be chucked into a shredder whole, which pulverizes the plastic cases, releases the electrolyte, and shreds the innards. Process water is added to dilute the sulfuric acid and flush away the plastic bits, which can be skimmed off while letting the lead parts sink. Everything has its own physical path through the process, and human hands need never touch the batteries, which makes for a very economical process that scales well. And even where the process is not entirely automated, the limited number of shapes and sizes of batteries, coupled with their relatively large size, makes orienting the batteries for quick disassembly easy.

Compare this to handling a lithium-ion battery pack. The form factor for these could range from a laptop battery to an old drill-driver battery pack to the guts of a wrecked electric vehicle. While most of these will be loaded with cells like the 18650, each one will differ in size and shape, and the number and orientation of cells within the pack will vary wildly. Most packs will also have some kind of circuit board inside, which requires a separate step to liberate and has to enter a different recycling stream. At least for now, this makes disassembly of lithium-ion packs the work of human hands, which makes it an expensive proposition that scales poorly.

The differences between the effort needed to recycle lead-acid and lithium-ion batteries drive the overall economics of the process. If you look at the price of lithium ($17,000 / ton) versus lead ($2,600 / ton), it would seem that lithium recycling would be more profitable. But if you can’t get the lithium out of batteries effectively, it doesn’t matter how much the stuff would earn. For recyclers, the value proposition is skewed heavily in favor of lead, where huge feedstock volumes and easy extraction methods make recycling a profitable venture. And that’s not to mention the dangers of mixing lithium batteries into the lead-acid recycling stream.

All this leads to the sad fact that currently, 97% of lithium-ion batteries are not recycled. With a huge new input of dead batteries about to hit the waste stream as the first generations of electric and hybrid vehicles reach the end of their service lives, this is going to be a problem we’re going to need to deal with soon. The fact that both lithium and cobalt are sourced from politically unstable regions of the world will probably help skew the economics of recycling such that it makes more sense to recover the minerals rather than commit them in an unusable state to the ground whence they came. Things will likely change, but for now, lithium-ion batteries are a dead end technology.

DIY Arc Light Makes An Unnecessarily Powerful Bicycle Headlight

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Remember when tricking out a bike with a headlight meant clamping a big, chrome, bullet-shaped light to your handlebar and bolting a small generator to your front fork? Turning on the headlight meant flipping the generator into contact with the front wheel, powering the incandescent bulb for the few feet it took for the drag thus introduced to grind you to a halt. This ridiculous arc-lamp bicycle headlight is not that. Not by a long shot.

We’re used to seeing [Alex] doing all manner of improbable, and sometimes impossible, things on his popular KREOSAN YouTube channel. And we’re also used to watching his videos in Russian, which detracts not a whit  from the entertainment value for Andglophones; subtitles are provided for the unadventurous, however. The electrodes for his arc light are graphite brushes from an electric streetcar, while the battery is an incredibly sketchy-looking collection of 98 18650 lithium-ion cells. A scary rat’s nest of coiled cable acts as a ballast to mitigate the effects of shorting when the arc is struck. The reflector is an old satellite TV dish covered in foil tape with the electrodes sitting in a makeshift holder where the feedhorn used to be. It’s bright, it’s noisy, it’s dangerous, and it smokes like a fiend, but we love it.

Mounting it to the front of the bike was just for fun, of course, and it works despite the janky nature of the construction. The neighbors into whose apartments the light was projected could not be reached for comment, but we assume they were as amused as we were.

Thanks for the tip, [Nikolai].


Cheaply Charging Cylindrical Cells

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For one reason or another, a lot of us have a bunch of 18650 cells sitting around. Whether they’re for flashlights, our fancy new vape pen, remote controlled toys, or something more obscure, there is a need to charge a bunch of lithium ion cells all at once. This project, by [Daren Schwenke], is the way to do it. It’ll charge ten 18650 cells quickly using a stock ATX power supply and less than twenty bucks in Amazon Prime parts.

The idea began when [Daren] realized his desktop lithium ion charger took between 4-6 hours to fully charge two 18650 cells. With a Mountainboard project, or a big ‘ol electric skateboard waiting in the wings, [Daren] realized there had to be a better solution to charging a bunch of 18650 cells. There is, and it’s those twenty bucks at Amazon and a few 3D printed parts.

The relevant parts are just a ten-pack of 18650 cell holders (with PC pins) and a ten-pack of 5V, 1A charging modules (non-referral Amazon link, support truly independent journalism) meant to be the brains of a small USB power bank. These parts were wired up to the 5V rail of a discarded ATX power supply (free, because you can scavenge these anywhere, and everything was wrapped up with a neat little 3D printed mount.

Is this the safest way to charge lithium ion cells? No, because you can build a similar project with bailing wire. There is no reverse polarity protection, and if there’s one thing you never want to do, it’s reverse the polarity. This is, however, a very effective and very cheap solution to charging a bunch of batteries. It does what it says it’ll do, nothing more.

Better Battery Management Through Chemistry

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The lead-acid rechargeable battery is a not-quite-modern marvel. Super reliable and easy to use, charging it is just a matter of applying a fixed voltage to it and waiting a while; eventually the battery is charged and stays topped off, and that’s it. Their ease is countered by their size, weight, energy density, and toxic materials.

The lithium battery is the new hotness, but their high energy density means a pretty small package that can get very angry and dangerous when mishandled. Academics have been searching for safer batteries, better charge management systems, and longer lasting battery formulations that can be recharged thousands of times, and a recent publication is generating a lot of excitement about it.

Consider the requirements for a battery cell in an electric car:

  • High energy density (Lots of power stored in a small size)
  • Quick charge ability
  • High discharge ability
  • MANY recharge cycles
  • Low self-discharge
  • Safe

Lithium ion batteries are the best option we have right now, but there are a variety of Li-ion chemistries, and depending on the expected use and balancing and charging, different chemistries can be optimized for different performance characteristics. There’s no perfect battery yet, and conflicting requirements mean that the battery market will likely always have some options.

How a Li+ion Works

How a Lithium battery discharges
How a Li-ion battery discharges. Image by Sdk16420 CC-BY-SA

All batteries work the same way. There are 3 components: an anode, a cathode, and an electrolyte. A chemical reaction between the electrolyte and the electrodes (the anode and cathode) creates ions near one part of an electrode and electrons on the other, giving the two terminals a difference in potential. The two electrodes are made of different materials. The anode is graphite bound to copper, and the cathode is some lithium crystal bound to aluminum. The electrolyte is a sort of insulator, so the electrons are better off going through the circuit from one electrode to the other than to make an internal short. Once the reaction is complete, the battery is dead, and the reaction won’t happen unless there’s a path for the electrons to move (aka a closed circuit). To charge a battery, the process is reversed, and power applied to the electrolyte undoes the chemical reaction. Not all electrolytes are created the same, however, and the chemistry of a non-rechargeable battery means that it can store more energy, but applying power in reverse doesn’t undo the chemical reaction.

It’s best to maximize the battery by taking advantage of surface area, so the anode/electrolyte/cathode sandwich benefits from being as thin as possible with lots of area touching. Also, the sandwich has a few more slices of materials with porous layers between them to allow ion transfer without allowing material migration. Now take your battery sandwich and put a bunch of them together in a stack with separators, and you have either a pouch battery (cheap cell in a silver casing), a prismatic battery (fancy cell that you’d find on a laptop), or roll it into a small tube and you have a cylindrical battery (like the 18650 or AA).

The Million Mile Battery

You may have seen the news recently about Tesla’s Million Mile battery. It was actually a group of researchers from Dalhousie University in Halifax, Canada under contract with Tesla, but they did a LOT of testing of a variety of Li-ion batteries to find the best chemistries and use profiles and charging profiles. The million mile battery is just a good PR term to describe the research that optimized some battery formulations and resulted in much longer lifetimes. The full paper is filled with technical jargon, so I spent the weekend learning all about batteries in order to distill it here. You’re welcome.

The first thing to note about their million mile formula is that it doesn’t represent most current drivers that identify as average commuters. Rather, they’re targeting the use cases that will use the vehicle almost constantly and charge when the battery is empty. This would be for long-haul semi trucks, taxis, and buses. Their term was 100% DOD, or Depth of Discharge, where they run the battery all the way to empty before charging it back up again, unlike a cell phone which is usually plugged in every night no matter the state of charge.

Findings: Batteries Like it Cool; Hot New Chemical Formulations

They found that temperature matters a lot. A battery that spent most of its life at 20ºC resulted in a longer lasting battery than at 40ºC, but a battery that spent time at a high temperature and then went to a lower temperature then lost its capacity at the same rate as other low-temperature samples. In other words, a cell at higher temperatures loses capacity faster, and a cell at lower temperature still loses capacity over time but not as fast, and a single battery can move anywhere on that line without memory. The lower temperature meant less degradation at a molecular level, with fewer cracks, dendrites, gas pockets, etc. They couldn’t stress enough how important it was to keep everything cool.

The research team spent a lot of time in previous studies looking at other chemistries, but had primarily settled on NMC532/graphite as their electrodes (as has most of the research community). In chemistry terms, NMC532 is another name for LiNi0.5Mn0.3Co0.2O2, and in lay-speak it means the cathode is mostly lithium crystals, with a sprinkling of nickel, manganese, cobalt, and oxygen, and the anode is graphite (though research into graphene is promising).

Calling the battery NMC532/graphite isn’t quite sufficient, though. You still need to specify an electrolyte. The electrolyte is a slurry of LiPF6 and solvents and additives with fun names to say out loud, like dimethyl carbonate and ethylene sulfate. In this study they tried out a few combinations of solvents. The additives can also change the performance of the cell, giving it a higher charge/discharge rating at the expense of overall lifetime, or vice versa. Based on previous studies, they were really excited about 2 different additive formulas (2%FEC+1%LFO, and 2%VC+1%DTD), though they discovered that the two had different performances at different temperatures, so they suggested that the choice of additives could be application-specific. In the production of cells, usually the dry packs are manufactured, and then the wet electrolyte slurry is injected. See Sparkfun’s tutorial tour through a manufacturing plant for a visual story of the process.

With this special formula, and maintaining a low temperature, they were able to minimize the two main things that cause degradation of a battery; lithium inventory loss, and increased impedance. Generally, over time the lithium ions move around and eventually get themselves into locations that aren’t helpful for the battery. They can get electrically isolated, they can group together into plates and dendrites and surface films, and they can react with other components of the cell and become unavailable for charging/discharging. The dendrites are particularly bad because these sharp little lithium needles can pierce the separators, causing a short circuit in the cell, which then heats up and causes a runaway reaction that ultimately explodes. Impedance is increased through electrode corrosion or just in general less surface area being available, either through reactions or cracking or resistive surface layers forming and blocking the electrode.

Ways that a LiPo battery can degrade
There are lots of ways a LiPo cell can degrade, but most of them are summarized as “atoms move where they shouldn’t.” Image via Science Direct

One of the reasons this study got so much attention is that is was thorough and entirely open. It took them 3 years, running thousands of cycles on each battery, with extremely accurate chargers and dischargers to record the capacity, to get the most complete data they could. Usually accelerated lifetime testing on batteries is difficult, as it’s still putting the battery at higher charge/discharge rates than expected in real life, with less recovery time, so the fact that they put so much time into this testing means the results are more realistic. They also specifically said:

Full details of these cells including electrode compositions, electrode loadings, electrolyte compositions, additives used, etc. have been provided in contrast to literature reports using commercial cells. This has been done so that others can re-create these cells and use them as benchmarks for their own R+D efforts be they in the spaces of Li-ion cells or “beyond Li-ion cells”.

It’s refreshing to see commercially funded research made publicly available, and Creative Commons no less.

Despite its openness, we probably won’t be seeing homebrew Li-ion batteries soon (but we’d love to cover it if any of you try). From the battery application community we may be seeing battery chemistry change towards the formulation suggested, and we’ll likely see a lot more attention paid to cooling, as that significantly improves their life. And we’re pretty certain that if you want a battery pack, Tesla will soon be happy to sell you one of theirs from their gigafactories.

Author’s Note: Some people pointed out that I used the term LiPo when I should have used Li-ion. They were, of course, correct, and I’ve updated the article accordingly.

Hackaday Links: October 20, 2019

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It’s Nobel season again, with announcements of the prizes in literature, economics, medicine, physics, and chemistry going to worthies the world over. The wording of the Nobel citations are usually a vast oversimplification of decades of research and end up being a scientific word salad. But this year’s chemistry Nobel citation couldn’t be simpler: “For the development of lithium-ion batteries”. John Goodenough, Stanley Whittingham, and Akira Yoshino share the prize for separate work stretching back to the oil embargo of the early 1970s, when Goodenough invented the first lithium cathode. Wittingham made the major discovery in 1980 that adding cobalt improved the lithium cathode immensely, and Yoshino turned both discoveries into the world’s first practical lithium-ion battery in 1985. Normally, Nobel-worthy achievements are somewhat esoteric and cover a broad area of discovery that few ordinary people can relate to, but this is one that most of us literally carry around every day.

What’s going on with Lulzbot? Nothing good, if the reports of mass layoffs and employee lawsuits are to be believed. Aleph Objects, the Colorado company that manufactures the Lulzbot 3D printer, announced that they would be closing down the business and selling off the remaining inventory of products by the end of October. There was a reported mass layoff on October 11, with 90 of its 113 employees getting a pink slip. One of the employees filed a class-action suit in federal court, alleging that Aleph failed to give 60 days notice of terminations, which a company with more than 100 employees is required to do under federal law. As for the reason for the closure, nobody in the company’s leadership is commenting aside from the usual “streamlining operations” talk. Could it be that the flood of cheap 3D printers from China has commoditized the market, making it too hard for any manufacturer to stand out on features? If so, we may see other printer makers go under too.

For all the reported hardships of life aboard the International Space Station – the problems with zero-gravity personal hygiene, the lack of privacy, and an aroma that ranges from machine-shop to sweaty gym sock – the reward must be those few moments when an astronaut gets to go into the cupola at night and watch the Earth slide by. They all snap pictures, of course, but surprisingly few of them are cataloged or cross-referenced to the position of the ISS. So there’s a huge backlog of beautiful but unknown cities around the planet that. Lost at Night aims to change that by enlisting the pattern-matching abilities of volunteers to compare problem images with known images of the night lights of cities around the world. If nothing else, it’s a good way to get a glimpse at what the astronauts get to see.

Which Pi is the best Pi when it comes to machine learning? That depends on a lot of things, and Evan at Edje Electronics has done some good work comparing the Pi 3 and Pi 4 in a machine vision application. The SSD-MobileNet model was compiled to run on TensorFlow, TF Lite, or the Coral USB accelerator, using both a Pi 3 and a Pi 4. Evan drove around with each rig as a dashcam, capturing typical street scenes and measuring the frame rate from each setup. It’s perhaps no surprise that the Pi 4 and Coral setup won the day, but the degree to which it won was unexpected. It blew everything else away with 34.4 fps; the other five setups ranged from 1.37 to 12.9 fps. Interesting results, and good to keep in mind for your next machine vision project.

Have you accounted for shrinkage? No, not that shrinkage – shrinkage in your 3D-printed parts. James Clough ran into shrinkage issues with a part that needed to match up to a PCB he made. It didn’t, and he shared a thorough analysis of the problem and its solution. While we haven’t run into this problem yet, we can see how it happened – pretty much everything, including PLA, shrinks as it cools. He simply scaled up the model slightly before printing, which is a good tip to keep in mind.

And finally, if you’ve ever tried to break a bundle of spaghetti in half before dropping it in boiling water, you likely know the heartbreak of multiple breakage – many of the strands will fracture into three or more pieces, with the shorter bits shooting away like so much kitchen shrapnel. Because the world apparently has no big problems left to solve, a group of scientists has now figured out how to break spaghetti into only two pieces. Oh sure, they mask it in paper with the lofty title “Controlling fracture cascades through twisting and quenching”, but what it boils down to is applying an axial twist to the spaghetti before bending. That reduces the amount of bending needed to break the pasta, which reduces the shock that propagates along the strand and causes multiple breaks. They even built a machine to do just that, but since it only breaks a strand at a time, clearly there’s room for improvement. So get hacking!

The Quest To Find A Second Life For Electric Vehicle Batteries

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Rechargeable lithium chemistry battery cells found their mass market foothold in the field of personal electronics. The technology has since matured enough to be scaled up (in both physical size and production volume) to electric cars, making long range EVs far more economical than what was possible using earlier batteries. Would the new economics also make battery reuse a profitable business? Eric Lundgren is one of those willing to make a run at it, and [Gizmodo] took a look at his latest venture.

This man is a serial entrepreneur, though his previous business idea was not successful as it involved “reusing” trademarks that were not his to use. Fortunately this new business BigBattery appears to be on far more solid legal footing, disassembling battery packs from retired electric vehicles and repacking cells for other purposes. Typically EV batteries are deemed “worn out” when their capacity drops below a certain percentage (70% is a common bar) but that reduced capacity could still be useful outside of an EV. And when battery packs are retired due to problems elsewhere in the car, or just suffering from a few bad cells, it’s possible to extract units in far better shape.

We’ve been interested in how to make the best use of rechargeable lithium batteries. Ranging from tech notes helping battery reuse, to a comparison of different types, to looking at how their end-of-life recycling will be different from lead-acid batteries. Not to mention countless project wins and fails in between. A recurring theme is the volatility of mistreated or misbehaving batteries. Seeing a number of EV battery packs stacked on pallets and shelves, presumably filled with cells of undetermined quality, fills us with unease. Like the rest of California, Chatsworth is under earthquake risk, and the town was uncomfortably close to some wildfires in 2019. Eric is quick to give assurance that employees are given regular safety training and the facility conforms to all applicable workplace safety rules. But did those rules consider warehouses packed full of high capacity lithium battery cells of unknown quality? We expect that, like the business itself, standards for safety will evolve.

Concerns on safety aside, a successful business here would mean electric vehicles have indeed given battery reuse a profitable economy of scale that tiny little cell phone and laptop batteries could not reach. We are optimistic that Eric and other like-minded people pursuing similar goals can evolve this concept into a bright spot in our otherwise woeful state of e-waste handling.

A Beginner’s Guide to Lithium Rechargeable Batteries

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Batteries were once heavy, awkward things, delivering only a limp amount of current for their size and weight. Thankfully, over time, technology has improved, and in 2020, we’re blessed with capable, high-power lithium polymer batteries that can provide all the power your mobile project could possibly need. There are some considerations one must make in their use however, so read on for a primer on how to properly use LiPos in your project!

So Many Types!

With the first commercial lithium-ion battery entering the market in 1991, the (nearly) 30 years since have seen rapid development. This has led to a proliferation of different technologies and types of battery, depending on construction and materials used. In order to treat your batteries properly, it’s important to know what you’ve got, so paying attention to this is critical.

18650 lithium-ion cells as found in a laptop battery. Packs like these are normally spot welded together with nickel strips.

Lithium-ion, or Li-ion typically refers to the overarching technology of rechargeable lithium batteries, but also specifically refers to the traditional cells built in cylindrical metal bodies. The venerable 18650 is one such cell, but a large variety of sizes and types exist. Their stout casings make these cells popular for rough-and-tumble vehicle use.

Lithium-Polymer, or Li-Po refers to a lithium-ion battery that uses a polymer electrolyte instead of a liquid electrolyte. This enables the construction of pouch cells with different geometries. This flexibility of design makes lithium-polymer batteries useful in applications like smartphones and tablets, where a high-capacity battery is needed and a flat form factor is desirable. They’re also commonly used in radio-control models, where their lightweight construction is a huge benefit for flying vehicles.

Lithium-polymer pouch packs, designed for RC use. The top pack is an HV type.

Lithium-HV, or High Voltage Lithium are lithium polymer batteries that use a special silicon-graphene additive on the positive terminal, which resists damage at higher voltages. When charged above 4.2V, most lithium batteries exhibit significant capacity loss and reduced lifespan. However, by using this additive, cells can be charged to 4.35V without exhibiting these negative effects. This extra voltage provides up to a 10% gain in energy density over conventional lithium polymer batteries.

Lithium-Iron-Phosphate, or LiFePObatteries are an altered lithium-ion chemistry, which offers the benefits of withstanding more charge/discharge cycles, while losing some energy density in the tradeoff. They operate ideally between 3.0V-3.65V, instead of the more typical 3.0-4.2V range of a standard lithium-ion chemistry. This, combined with a very flat discharge voltage curve, makes them ideal replacements for 12V lead-acid batteries in many applications, where four cells substitute for the original six. They’re generally more stable, with lower rates of self-discharge and capacity loss over time.

Respect The Limits

Get it wrong, and results can be intense.

Moreso than most battery types, lithium cells are not tolerant of mistreatment. Discharging cells below their low voltage limit leads to the formation of copper dendrites, which can reduce cell capacity or short circuit them entirely. Overcharging cells causes damage to the anode by lithium plating out of solution, creating lithium dendrites, often leading to a short circuit or full thermal runaway of the battery, leading to a release of smoke and flames. Each cell in a pack must also be kept at the same voltage as its neighbors, to avoid cells getting damaged prematurely.

It’s important not to charge lithium cells too quickly. Ambient temperatures also play a big role in battery performance. Lithium batteries don’t appreciate being taken down below freezing, particularly when they’re already fully charged. Below 0°C, charging is impractical, as metallic lithium can electroplate at the negative electrode, causing major damage or even short circuiting the cell. Between 0-5°C, charging is possible, but must be done slowly. Damage will tend to occur when batteries are charged at temperatures above 45°C, too.

Working outside these parameters will quickly lead to a dead battery at best, or a fire and explosion at worst. They also tend to swell up, outgas, and just generally become unseemly to deal with. On the surface this can seem like a lot to deal with. Thankfully the battery-electronics complex has worked hard to solve these issues. With the proper hardware and precautions, it’s possible to use lithium batteries safely and effectively. But anyone working with these chemistries should familiarize themselves with the hazards. Bob Baddeley published a great article on Li-Ion safety back in November.

Battery Tending

For applications working with bare cells or packs, such as when using LiPo batteries in RC models, simply using a lithium-ready charger is enough. The balance leads should be hooked up during charging, particularly when the battery has been taken to a fully-discharged state in use. Ensuring that a smart charger is used with the correct voltage limits (particularly when using LiFePO4 and HV packs) will make sure you get the most out of your batteries. Make sure you’ve got some method to stop discharging the batteries when voltage gets low, whether by a warning light, buzzer, or automatic shutdown.

Modules like these are great for integrating a lithium battery into your prototypes.

If you’re producing a device that needs a permanently integrated battery, protection and charging circuits are just the ticket. Off-the-shelf modules and ICs exist to take the hassle out of managing a lithium-ion battery. A wide variety are available, from those that act as a simple low-voltage cutoff to complete charging and protection solutions. Companies like Adafruit sell modules that are a great starting point for those eager to integrate a neat charge and battery solution without having to spin up PCBs themselves. However, since these designs are open source it will be easy to integrate the circuit design into your own PCB in the future.

A battery management system for a 12-cell pack, capable of delivering up to 60A.

For larger applications featuring custom-built battery packs, a battery management system is a good choice. Basically, a BMS is not much different from a battery protection IC or similar, simply being designed for larger applications. A BMS is typically used on packs of 10 cells and up, used in transport applications like electric bikes and other rideables. The BMS is soldered directly to the battery pack, including a connection to each individual cell. Its purpose is keeping the cells balanced, limiting the maximum discharge current for safety reasons, and of course controlling the recharging process. Experienced pack builders will often integrate a BMS inside the battery’s housing or covering, leaving simply a discharge port and a charge port accessible. This allows the end user to easily drop a battery into a project vehicle without having to worry about handling protection themselves.

If your application is particularly critical and needs to withstand environmental extremes, you’ll want to monitor battery temperature. Keeping an eye on cell temps, particularly during the charge process, is a great way to protect your battery against damage. High-feature protection chips and battery management systems have provisions to monitor pack temperatures in order to achieve this. At this level, you’ll likely be building custom packs, thus allowing you to install thermocouples at precise locations during the build. For high-power installations, temperature management is mandatory, with virtually all e-bikes and electric cars containing hardware to monitor battery temperatures and control systems accordingly.

In Summary

Lithium-ion batteries can bite, but used properly, they offer great performance and are more than safe enough for most applications. The key is to use the correct hardware, to make sure you’re avoiding crossing voltage and temperature limits that can lead to disaster. Hopefully, this guide serves you well as you seek to integrate lithium power into your own projects. And, in the unlikely event you do have an amusing battery mishap, be sure to do a diagnosis and hit up the tipsline. Happy hacking!

Electric RC Plane Flies For Almost 11 Hours

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Electric RC aircraft are not known for long flight times, with multirotors usually doing 20-45 minutes, while most fixed wings will struggle to get past two hours. [Matthew Heiskell] blew these numbers out of the water with a 10 hour 45 minute flight with an RC plane on battery power. Condensed video after the break.

Flight stats right before touchdown. Flight time in minutes on the left, and miles travelled second from the top on the right.

The secret? An efficient aircraft, a well tuned autopilot and a massive battery. [Matthew] built a custom 4S 50 Ah li-ion battery pack from LG 21700 cells, with a weight of 2.85 kg (6.3 lbs). The airframe is a Phoenix 2400 motor glider, with a 2.4 m wingspan, powered by a 600 Kv brushless motor turning a 12 x 12 propeller. The 30 A ESC’s low voltage cutoff was disabled to ensure every bit of juice from the battery was available.

To improve efficiency and eliminate the need to maintain manual control for the marathon flight, a GPS and Matek 405 Wing flight controller running ArduPilot was added. ArduPilot is far from plug and play, so [Matthew] would have had to spend a lot of timing tuning and testing parameters for maximum flight efficiency. We are really curious to see if it’s possible to push the flight time even further by improving aerodynamics around the protruding battery, adding a pitot tube sensor to hold the perfect airspeed speed on the lift-drag curve, and possibly making use of thermals with ArduPilot’s new soaring feature.

A few of you are probably thinking, “Solar panels!”, and so did Matthew. He has another set of wings covered in them that he used to do a seven-hour flight. While it should theoretically increase flight time, he found that there were a number of significant disadvantages. Besides the added weight, electrical complexity and weather dependence, the solar cells are difficult to integrate into the wings without reducing aerodynamic efficiency. Taking into account what we’ve already seen of [rcflightest]’s various experiments/struggles with solar planes, we are starting to wonder if it’s really worth the trouble.

Murata To Deliver Solid State Batteries to Market In the Fall

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Solid state batteries have long been promised to us as the solution to our energy storage needs. Theoretically capable of greater storage densities than existing lithium-ion and lithium-polymer cells, while being far safer to boot, they would offer a huge performance boost in all manner of applications.

For those of us dreaming of a 1,000-mile range electric car or a 14-kilowatt power drill, the simple fact remains that the technology just isn’t quite there yet. However, Murata Manufacturing Co., Ltd. has just announced that it plans to ship solid state batteries in the fall, which from a glance at the calendar is just weeks away.

It’s exciting news, and we’re sure you’re dying to know – just what are they planning to ship, and how capable are the batteries? Let’s dive in.

Benefits of Solid State over Li-Ion/Li-Po

A graph published by Murata in 2019 regarding the expected performance regime of their upcoming solid-state battery technology.

If you’re unfamiliar with solid-state batteries, the basic idea is to build a battery using only solid materials, eliminating liquid electrolytes as used in lithium-ion batteries. The hope is that this would allow the use of lithium metal as an anode material, which promises a far higher energy density than existing battery designs. Raw lithium metal isn’t used in current battery anodes as it grows harmful dendrites that quickly destroy a battery. The solid state design also brings other benefits, such as greater safety due to the elimination of the flammable liquid electrolyte, and thus faster charging as temperature limits become less critical to avoid blowing everything to pieces. The compelling benefits are there, yet have thus far proved difficult to achieve.

As for Murata, it’s a company well known for producing multilayer ceramic capacitors (MLCC) and other similar devices, though they have been branching out into battery technologies after purchasing Sony’s battery division back in 2017. With these new solid state batteries, the company hopes to stake its claim as a major competitor in the battery market, after having invested hundreds of millions of dollars in the business.

Starting Small, But Permanent

This promotional image gives us the best look thus far at what a potential solid-state battery from Murata might look like. The image suggests that the cell itself will be combined with the necessary sensors and protection circuitry all in one single solderable package.

According to Murata’s own report from 2019, their new batteries will be aimed at the wearables and Internet of Things market. The batteries will be on the order of 2 to 25 mAh in capacity, based on graphics in the press release, with energy densities in the realm of 500 Wh/L. This puts the batteries in the realm slightly above the performance of current lithium-ion cells. It also far exceeds existing solid state designs, currently only really used in pacemakers and other very-low-power applications. The company aims to eventually deliver 100,000 parts a month, though will ramp up production slowly over the next 12 months or so.

Murata’s batteries will thus be small, compact, and not wildly powerful. However, their solid state nature brings one exciting benefit — they’ll be able to be soldered directly to PCBs in much the same way as any other component. Solid state batteries have many admirable benefits like these, in fact. By virtue of eliminating liquid electrolytes, the batteries are typically non-flammable and far hardier than traditional lithium-ion cells.

YouTuber [Great Scott] tested prototype solid-state cells from ProLogium. The cells could be punctured with a nail or cut with shears without catching fire or sustaining terminal damage.
Those hoping for solid-state cells to drop this year with huge current delivery numbers and stratospheric energy densities might be disappointed. However, if big time solid state batteries like that were even close to ready, we’d have more to go on than just a simple press release by this stage. However, it is an exciting development. Through the use of ceramic coating technologies developed through their capacitor business, combined with learnings from the battery business purchased from Sony, Murata have seemingly managed to develop a viable solid state battery that outperforms the very basic, low power designs available thus far, and by significant margin.

Everyone Wants a Piece of This Emerging Sector

As we’ve reported, BMW are betting big on the technology, even as competitors like Fisker have fallen by the wayside. Toyota also intend to throw their hat in the ring, with just about every other automaker involved in one way or another. The reason is simple: if solid state batteries can live up to their promises, electric cars could see a huge performance boost almost overnight. Batteries with higher energy density would provide for much longer range between recharges, while the lack of flammable liquid electrolyte would lessen overheating risks and potentially allow faster charge times. These two fixes would leave the electric vehicle world to then solely contend with the infrastructure issue, which is already well on the way to being solved in some locations. It’s compelling stuff.

For all that to happen, though, will require plenty of research and development. That’s well underway, of course, with Electronic Design reporting on multiple cutting-edge projects in the solid-state battery space late last year. The inherent difficulty most projects face is in the separator material. Placed between the anode and cathode, the separator must allow for lithium ions to pass freely from one side of the battery to another, while resisting the formation of lithium dendrites that could short circuit the battery. There’s a wide variety of approaches and chemistries at play, with it being anyone’s guess as to which, if any, will come out on top.

There’s some fundamental science to be done yet, and with hundreds of millions of dollars pouring in to research labs around the world, there’s plenty going on. YouTuber [Just Have a Think] has been following along with these developments, and covers the Murata development along with the state of play in the automotive scene, if you want to dig a bit deeper into the developments.

We can’t wait until these devices are shipping en masse, particularly as densities and current capacity increase. The advent of a lighter, more powerful, and crucially, more robust battery should herald a new wave of projects and technologies in much the same way that lithium-ion batteries did 30 years ago.

[Main image via Murata online exhibition about solid state batteries]


Gorgeous Battery Welder Hits The Spot

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Robert Dunn holds a button in his hand for controlling a spot welder

Raise you’re hand if you’ve ever soldered directly to a battery even though you know better. We’ve all been there. Sometimes we get away with it when we have a small pack and don’t care about longevity. But when [Robert Dunn] needed to build a battery pack out of about 120 Lithium Ion cells, he knew that he had to do it The Right Way and use a battery spot welder. Of course, buying one is too simple for a hacker like [Robert]. And so it was that he decided to Build a Spot Welder from an old Microwave Oven and way too much mahogany, which you can view below the break.

A Battery Cell with a spot welding tab attached
Spot Welding leaves two familiar divots in the attached tab, which can be soldered or welded as need.

For the unfamiliar, a battery spot welder is the magical device that attaches tabs to rechargeable batteries. You’ll notice that all battery packs with cylindrical cells have a tab with two small dimples. These dimples are where high amperage electricity quickly heats the battery terminal and the tab until they’re red hot, welding them together. The operation is done and over in less than a second, well before any heat damage can be done. The tab can then be soldered to or spot welded to another cell.

One of the most critical parts of spot welding batteries is timing. While [Robert Dunn] admits that a 555 timer or even just a manual switch and relay could have done the job, he opted for an Arduino Uno with a 4 character 7 segment LED display that shows the welding time in milliseconds. A 3d printed trigger and welder handle wrap up the hardware nicely.

The build is topped off by a custom mahogany enclosure that is quite a bit overdone. But if one has the wood, the time, the tools and skills (and a YouTube channel perhaps?) there’s no reason not to put in the extra effort! [Robert]’s resulting build is almost too nice, but it’ll certainly get the job done.

Of course, spot welders are almost standard fare here at Hackaday, and we’ve covered The Good, The Bad, and The Solar. Do you have a battery welder project that deserves a spot in Hackaday’s rotation? By all means, send it over to the Tip Line!

Ask Hackaday: Why Don’t Automakers Make Their Own EV Batteries?

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Sales of electric vehicles continue to climb, topping three million cars worldwide last year. All these electric cars need batteries, of course, which means demand for rechargeable cells is through the roof.

All those cells have to come from somewhere, of course, and many are surprised to learn that automakers don’t manufacture EV batteries themselves. Instead, they’re typically sourced from outside suppliers. Today, you get to Ask Hackaday: why aren’t EV batteries manufactured by the automakers themselves?

Experience and Infrastructure

Battery manufacturers like CATL have invested heavily in production capacity to churn out cells in their billions. It’s not something that can be easily replicated overnight. Credit: CATL, YouTube

Automotive manufacturers actually outsource the development and production of many components of their vehicles. Your car rides on tires from companies like Bridgestone, Goodyear, and Falken, not Ford, Dodge, or Volkswagen. Similarly, FOX shocks are prized in off-road trucks like the Ford F-150 Raptor, and if you dig into your fuel management system, many of the pumps and sensors are probably made by Bosch.

The fact is, automakers don’t have the capacity to design and manufacture every single little component of their cars. Doing so would rarely make sense, either. Take oxygen sensors, for example. These delicate electronic components are complicated to manufacture, and require specific expertise. Any automaker designing their own would have to cover the full cost of R&D, and economies of scale would be limited by their own vehicle output. However, pretty much every car needs an oxygen sensor, so an outside company that supplies many automakers has an advantage. Their economies of scale are much larger, as they can offset R&D costs across millions of units sold to equip vehicles made by several different manufacturers.

Furthermore, automakers were not in the business of producing batteries by the time electric cars started to hit the market en masse. Starting a battery manufacturing effort from scratch is no mean feat, and would only have added to the difficulty of bringing an electric vehicle to market. Simply purchasing working batteries from an experienced supplier eliminates a whole lot of work, and most automakers have taken this path thus far. Even Tesla has gone this way, sourcing batteries from Panasonic and CATL among other companies over the years. Indeed, Panasonic invested heavily in Tesla’s Gigafactory, and runs much of the production equipment there.

Specialist battery manufacturers have the benefit of decades of experience in both battery chemistry, as well as the fundamentals of manufacturing cells. Batteries are delicate things, and getting their construction even slightly wrong can lead to dangerous fires. Scaling up production is difficult too, and with EVs often requiring hundreds or thousands of cells, monumental effort is required in this regard.

Thus, when it came time to produce electric vehicles, automakers had a choice. They could purchase cells from existing suppliers, with a known-good product and production lines ready to go. Or, they could start building their own factories, hiring battery experts, and begin the process of manufacturing their own cells. The latter route is fraught with hurdles, and requires years of effort to get a usable product available in real numbers. The former choice gets batteries in cars practically from Day 1. For automakers, the decision was easy.

What Could Go Wrong?

Chevrolet Bolt fires have been a major headache for General Motors, but the company’s costs will be reimbursed by supplier LG Chem, which was responsible for producing the defective cells. Credit: Cherokee County Fire and Emergency Service, press photo

Even the experts get it wrong sometimes, of course. The current Chevrolet Bolt uses cells sourced from supplier LG Chem. Torn anode tabs and folded separator materials in some cells lead to battery fires that destroyed several cars and prompted a huge recall effort. Over 140,000 cars have been recalled, causing brand damage and a huge headache for General Motors. However, as the fault was with the battery supplier, GM were able to point the finger outside, and LG agreed to pay $1.9 billion to cover the costs of rectifying the problem.

Thus, for a whole host of reasons, automakers typically source their batteries from external manufacturers. Car companies didn’t have the knowledge in house to make their own cells, nor did they have the factories to produce them en masse. Sourcing them outside also often provides a cheaper product with R&D costs essentially amortized across several customers. It also means that automakers were able to get to market sooner, and also provided companies with an opportunity for restitution if they were inadvertently supplied with poor product.

There are drawbacks, of course. Doing battery research and production in-house can net competitive advantages. If, for example, a company unlocks the secret to a new battery chemistry, they could produce cars with longer range and more performance than their rivals. However, it’s a risky game with no guarantee of success, and it can take many years to go from a successful lab-built cell to batteries that are ready for automotive use. Then, there’s the sticky problem of kitting out a factory to churn out millions of your special cells a year.

Winds of Change

Tesla hopes to bring the advanced tabless 4680 batteries to market, but is having to invest heavily to get production lines up and running. Credit: Tesla

Competition in the automotive world has been fairly level for some time, with emissions regulations and mature engine technology meaning that no one automaker had any wild advantage over another. However, being the only company with access to a new class of battery could be an absolute gamechanger. It’s easy to visualize now—imagine if only one company had access to lithium cells, while everyone else was stuck with nickel metal hydride technology. Cars with lithium batteries now have ranges that can exceed 400 miles. A car built with NiMH cells would be lucky to have a third of that, while being heavier and unable to deliver anywhere near as much current for hard acceleration.

Tesla are starting to look into vertical integration by producing their new tabless cells in-house, a step that it took after over a decade in the EV industry. BMW are doing much the same, investing deeply into solid-state batteries. These technologies could provide range gains in the double-digit percentages, and if built by the automakers themselves, could be unavailable to rivals, providing a major advantage in the marketplace.

As automakers grow more familiar with electric vehicle technology, expect more players to make steps towards producing their own batteries. However, others will continue to see the value in partnerships with established players, investing in new technologies and production capacity at arms length. There’s no one right way in business, of course, but there are always plenty of wrong ones. Traditionally-conservative auto companies will tread carefully as always, while hot upstarts like Tesla will be the ones making the drastic moves.

Li-ion Battery Low-Level Intricacies Explained Excellently

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Screenshot from the video in question, showing 12:54 of the video, demonstrating how the electrons are being exchanged when circuit is completed

There’s a lot of magic in Lithium-ion batteries that we typically take for granted and don’t dig deeper into. Why is the typical full charge voltage 4.2 V and not the more convenient 5 V, why is CC/CV charging needed, and what’s up with all the fires? [The Limiting Factor] released a video that explains the low-level workings of Lithium-ion batteries in a very accessible way – specifically going into ion and electron ion exchange happening between the anode and the cathode, during both the charge and the discharge cycle. The video’s great illustrative power comes from an impressively sized investment of animation, script-writing and narration work – [The Limiting Factor] describes the effort as “16 months of animation design”, and this is no typical “whiteboard sketch” explainer video.

This is 16 minutes of pay-full-attention learning material that will have you glued to your screen, and the only reason it doesn’t explain every single thing about Lithium-ion batteries is because it’s that extensive of a topic, it would require a video series when done in a professional format like this. Instead, this is an excellent intro to help you build a core of solid understanding when it comes to Li-ion battery internals, elaborating on everything that’s relevant to the level being explored – be it the SEI layer and the organic additives, or the nitty-gritty of the ion and electron exchange specifics. We can’t help but hope that more videos like this one are coming soon (or as soon as they realistically can), expanding our understanding of all the other levels of a Li-ion battery cell.

Last video from [The Limiting Factor] was an 1-hour banger breaking down all the decisions made in a Tesla Battery Day presentation in similarly impressive level of detail, and we appreciate them making a general-purpose insight video – lately, it’s become clear we need to go more in-depth on such topics. This year, we’ve covered a great comparison between supercapacitors and batteries and suitable applications for each one of those, as well as explained the automakers’ reluctance to make their own battery cells. In 2020, we did a breakdown of alternate battery chemistries that aim to replace Li-ion in some of its important applications, so if this topic catches your attention, check those articles out, too!

Thanks to [Kelvin Green] for the tip!

When Battery Rebuilds Go Wrong: Understanding BMSs, Spot Welders, and Safety

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Batteries are amazing. Batteries are horrible. Batteries are a necessary evil in today’s world of portable everything. If you’re reading this sentence, even if it’s not on a mobile device, somewhere there is a battery involved. They’re that ubiquitous. There’s another thing batteries are: Expensive! And at $350 each for a specialized battery, [Linus] of Linus Tech Tips decided to take battery repair into his own hands.

Rather than do a quick how-to video about putting new cells in an old enclosure, [Linus] does a deep dive into the equipment, skills, and safety measures needed when dealing with Lithium Ion cells. And if you watch the video through, you’ll even get to see those safety measures put to good use!

The real meat of the video comes toward the end however, with its explanation of the different Battery Management Systems (BMS), and a discussion of the difficulty of doing battery repair correctly and safely. Lastly, the video covers something a bit more sinister: Batteries that are made to resist being repaired with new cells; DRM for batteries, so to speak.

Overall we found the video informative, and we hope you do too. You might also enjoy this peek into the chemistry behind your favorite battery types.

Aluminium-Sulphur Batteries For Local Grid Storage?

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Lithium-Sulphur batteries have been on the cusp of commercial availability for a little while now, but nothing much has hit the shelves as of yet. There are still issues with lifetime due to cell degradation, and news about developments seems to be drying up a little. Not to worry, because MIT have come along with a new battery technology using some of the most available and cheap materials found on this planet of ours. The Aluminium-Sulphur battery developed has very promising characteristics for use with static and automotive applications, specifically its scalability and its incredible charge/discharge performance.

The cell is based upon electrodes constructed from aluminium metal and sulphur, with a electrolyte of molten catenated chloro-aluminate salts. With an operating temperature of around 100 degrees Celsius, you’re not going to want this in a mobile phone anytime soon, but that’s not the goal. The goal is the smoothing out of renewable energy sources, and localised electricity grid balancing. A major use case would be the mass charging of battery electric vehicles. As the number of charge points increases at any given location, so does the peak current needed from the grid. Aluminium-Sulphur batteries are touted to offer the solution to ease this, with their high peak discharge current capability enabling a much higher peak power delivery at the point of use.

Right now many of us have household solar installations utilising LiFePo battery technology, with the sheer cost of the battery units limiting the amount of capacity that is installed. Aluminium-Sulphur batteries could easily replace them at a fraction of the cost. With a cost-per-cell less than one-sixth that of Lithium Ion, and construction from extremely common materials, this might be just the technology to disconnect us from the global lithium and cobalt supply chains and enable many more people to generate and make use of electricity in our own homes, after all, the sun doesn’t shine all day.

Lithium-Sulphur technology still shows some promise, here’s a little thing about that. If you were wondering what the deal is with lithium, and why it could be a problem in the future, then do checkout this piece from a couple of years back. Food for thought, certainly.

via [MIT News]

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