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!
Continue reading “Li-ion Battery Low-Level Intricacies Explained Excellently”
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? Continue reading “Ask Hackaday: Why Don’t Automakers Make Their Own EV Batteries?”
It may not look like it in some parts of the world, but electric vehicles are gaining more and more market share over traditional forms of transportation. The fastest-growing segment is the e-bike, which some say are growing at 16x the rate of conventional bikes (which have grown at 15% during the pandemic). [Jacques Mattheij] rides an S-Pedelec, which is a sort of cross between a moped and an e-bike. There were a few downsides, and one of those was the pitiful range, which needed to be significantly upgraded.
The S-Pedelec that [Jacques] purchased is technically considered a moped, which means it needs to ride in traffic. The 500 watt-hour battery would only take him 45km (~28 miles) on a good day, which isn’t too bad but a problem if your battery runs down while in traffic, struggling to pedal a big heavy bicycle-like thing at car speed. You can swap batteries quickly, but carrying large unsecured extra batteries is a pain, and you need to stop to change them.
There were a few challenges to adding more batteries. The onboard BMS (battery management system) was incredibly picky with DRM and fussy about how many extra cells he could add. The solution that [Jacques] went with was to add an external balancer. This allowed him to add as many cells as he wanted while keeping the BMS happy. The battery geometry is a little wonky as he wanted to keep the pack within the frame. Putting it over the rear wheel would shift the center of gravity higher, changing the bike’s handling. After significant research and preparation, [Jacques] welded his custom battery back together with a spot welder. The final capacity came in at 2150wh (much better than the initial 500wh). An added benefit of the extra range is the higher speed, as the bike stays in the higher voltage domain for much longer. In eco mode, it can do 500km or 180km at full power.
It’s awe-inspiring, and we’re looking forward to seeing more e-bikes in the future. Maybe one day we’ll have tesla coil wireless e-bikes, but until then, we need to make do with battery packs.
After last year’s Tesla Battery Day presentation and the flurry of information that came out of it, [The Limiting Factor] spent many months researching the countless topics behind Tesla’s announced plans, the resource markets for everything from lithium to copper and cobalt, and what all of this means for electrical vehicles (EVs) as well as batteries for both battery-electric vehicles (BEVs) and power storage.
A number of these changes are immediate, such as the use of battery packs as a structural element to save the weight of a supporting structure, while others such as the shift away from cobalt in battery cathodes being a more long-term prospective, along with the plans for Tesla to set up its own lithium clay mining operation in the US. Also impossible to pin down: when the famous ‘tabless’ 4680 cells that Tesla plans to use instead of the current 18650 cells will be mass-produced and when they will enable the promised 16% increase.
Even so, in the over 1 hour long video (also linked below after the break), the overall perspective seems fairly optimistic, with LFP (lithium iron phosphate) batteries also getting a shout out. One obvious indication of process to point out is that the cobalt-free battery is already used in Model 3 Teslas, most commonly in Chinese models.
Continue reading “Lithium Mine To Battery Line: Tesla Battery Day And The Future Of EVs”
Telsa are one of the world’s biggest purchasers of batteries through their partnerships with manufacturers like Panasonic, LG and CATL. Their endless hunger for more cells is unlikely to be satiated anytime soon, as demand for electric cars and power storage continues to rise.
As announced at their Battery Day keynote, Tesla has been working hard on a broad spectrum of projects to take battery technology to the next level in order to reach their goal of 3 TWh annual production by 2030. One of the most interesting aspects of this was the announcement of Tesla’s new tabless 4680 battery, which will be manufactured by the company itself. Let’s take a look at what makes the 4680 so exciting, and why going tabless is such a big deal. Continue reading “Tesla’s New Tabless Batteries Unlock New Levels Of Performance”
The 18650 is perhaps the world’s favorite lithium battery, even if electric car manufacturers are beginning to move towards larger cells such as the 21700. Used heavily in laptops and flashlights, it packs a useful amount of energy into a compact, easy to use package. There’s a small industry that has developed around harvesting these cells from old equipment and repurposing them, and [MakerMan] wanted to a piece of the action. Thus, he created a cell testing station to help in the effort.
Make no mistake, this is not a grandiose smart cell tester with 40 slots that logs every last iota of data into a cloud spreadsheet for further analysis. Nope, this is good old fashioned batch processing. [MakerMan] designed a single PCB that replicates the same cell testing circuit four times. Since PCB houses generally have a minimum order quantity of ten units, [MakerMan] ended up with forty individual cell testers on ten PCBs. Once populated, the boards were installed on a wooden frame with an ATX power supply which supplies the juice to run the system.
Overall, it’s a quick, cheap way for capacity testing cells en masse that should serve [MakerMan] well. We look forward to seeing where these cells end up. We’ve seen his work before, too – with a self-built laser engraver a particular highlight. Video after the break.
Continue reading “Building A Cell Testing Station For 18650s”
Spectrum recently published a post on a new lithium sulfur battery technology specifically targeting electric aviation applications. Although lots of electric vehicles could benefit from the new technology, airplanes are especially sensitive to heavy batteries and lithium-sulfur batteries can weigh much less than modern batteries of equivalent capacity. The Spectrum post is from Oxis Energy who is about to fly tests with the new batteries which they claim have twice the energy density of conventional lithium-ion batteries. The company also claims the batteries are safer, which is another important consideration when flying through the sky.
The batteries have a cathode comprised of aluminum foil coated with carbon and sulfur — which avoids the use of cobalt, a cost driver in traditional lithium cell chemistries. The anode is pure lithium foil. Between the two electrodes is a separator soaked in an electrolyte. The company says the batteries go through multiple stages as they discharge, forming different chemical compounds that continue to produce electricity through chemical action.
The safety factor is due to the fact that, unlike lithium-ion cells, the new batteries don’t form dendrites that short out the cell. The cells do degrade over time, but not in a way that is likely to cause a short circuit. However, ceramic coatings may provide protection against this degradation in the future which would be another benefit compared to traditional lithium batteries.
We see a lot of exciting battery announcements, but we rarely see real products with them. Time will tell if the Oxis and similar batteries based on this technology will take root.