A proper gun safe should be difficult to open, but critically, allow instant access by the authorized party.[Dr. Gerg] got a SnapSafe and discovered that, while it was quite easy to use, it would also lock the owner out easily whenever the batteries would run out. Meant to be used with four AAA batteries and no way to recharge them externally, this could leave you royally screwed in the exact kind of situation where you need the gun safe to open. This, of course, meant that the AAA batteries had to go.
Having torn a few laptop batteries apart previously, [Dr. Gerg] had a small collection of Li-ion cells on hand – cylindrical and pouch cells alike. Swapping the AAA battery holder for one of these was no problem voltage-wise, and testing showed it working without a hitch! However, replacing one non-chargeable battery with another one wasn’t a viable way forward, so he also added charging using an Adafruit LiPo charger board. One 3D printed OpenSCAD-designed bracket later, he fit the board inside the safe’s frame – and then pulled out a USB cable for charging, turning the battery into a backup option and essentially creating an UPS for this safe. Nowadays, the safe sits constantly plugged into a wall socket, and [Dr. Gerg] estimates it should last for a few weeks even in case of USB power loss.
When you read about hacking gun safes, it’s usually because of their poor security, with even biometric models occasionally falling victim to prying fingers. There’s talk about moving the locking features into the guns themselves, but we remain skeptical. “Powering an electronically locked box with internal batteries” is a fun problem, and just recently, we’ve seen it solved in a different way in this intricate voice-activated lockbox.
Lithium (from Greek lithos or stone) is a silvery-white alkali metal that is the lightest solid element. Just one atomic step up from Helium, this magic metal seems to be in everything these days. In addition to forming the backbone of many kinds of batteries, it also is used in lubricants, mood-stabilizing drugs, and serves as an important additive in iron, steel, and aluminum production. Increasingly, the world is looking to store more and more power as phones, solar grids, and electric cars continue to rise in popularity, each equipped with lithium-based batteries. This translates to an ever-growing need for more lithium. So far production has struggled to keep pace with demand. This leads to the question, do we have enough lithium for everyone?
It takes around 138 lbs (63 kg) of 99.5% pure lithium to make a 70 kWh Tesla Model S battery pack. In 2016, OICA estimated that the world had 1.3 billion cars in use. If we replace every car with an electric version, we would need 179 billion pounds or 89.5 million tons (81 million tonnes) of lithium. That’s just the cars. That doesn’t include smartphones, laptops, home power systems, massive grid storage projects, and thousands of other products that use lithium batteries.
In 2019 the US Geological Survey estimated the world reserves of identified lithium was 17 million tonnes. Including the unidentified, the estimated total worldwide lithium was 62 million tonnes. While neither of these estimates is at that 89 million ton mark, why is there such a large gap between the identified and estimated total? And given the general rule of thumb that the lighter a nucleus is, the more abundant the element is, shouldn’t there be more lithium reserves? After all, the US Geological Survey estimates there are around 2.1 billion tonnes of identified copper and an additional 3.5 billion tonnes that have yet to be discovered. Why is there a factor of 100x separating these two elements?
Continue reading “Lithium: What Is It And Do We Have Enough?”
Lithium ion batteries have been a revolutionary technology. Their high energy and power density has made the electric car a practical reality, enabled grid storage for renewable energy, and put powerful computers in the palm of the hand. However, if there’s one thing humanity is known for, it’s always wanting more.
Potential contenders for the title of ultimate battery technology are out there, but it will take a major shift to dethrone lithium-ion from the top of the tree.
Dominant For Good Reason
Lithium-ion batteries were first developed by Stanley Whittingham, working at Exxon, who were looking to diversify away from oil in the midst of the major energy crises of the 1970s. Over the years, the technology was developed further, with work by John Goodenough (a superb hacker name if we’ve ever heard one) and Akira Yoshino increasing performance with improved cathode and anode materials. Commercialization was first achieved by Keizaburo Tozawa, working at Sony to develop a better battery for the company’s line of camcorders. Continue reading “Potential Contenders For Battery Supremacy”
Most of us know the basics of building packs of lithium-ion batteries. We’re familiar with cell balancing and the need for protection circuitry, and we understand the intricacies of the various serial and parallel configurations. It’s still a process that can be daunting for the first-time pack-builder though, because the other thing that most of us know about lithium ion batteries is that getting things wrong can cause fires. Rule zero of hackerspaces is “Don’t be on fire”, so what’s to be done? Fortunately [Adam Bender] is on hand with an extremely comprehensive two-part guide to designing and building lithium-ion battery packs from cylindrical 18650 cells.
In one sense we think the two-parter is in the wrong order. Part two takes us through all the technical details and theory, from lithium-ion chemistry to battery management systems and spot-welding nickel busbars, while part one shows us the construction of his battery pack. There are also a couple of videos, which we’ve placed below the break. It’s still not a job for the faint-hearted, but we’d say he’s produced about as professional and safe a pack as possible.
If spot welding worries you then it might be possible to build a pack without it. But it’s always worth considering: would you be better served buying one?
Continue reading “An Exhaustive Guide To Building 18650 Packs”
Many of us will own a lithium-ion power pack or two, usually a brick containing a few 18650 cylindrical cells and a 5 V converter for USB charging a cellphone. They’re an extremely useful item to have in your carry-around, for a bit of extra battery life when your day’s Hackaday reading has provided a worthy use for most of your charge. These pack are though by their very nature inflexible, no matter how many cells you own, the pack will only ever contain the number with which it was shipped. Worse, when those cells are discharged or even reach the end of their lives, they can’t be swapped for fresh ones. [Isaacporras] has a solution for these problems which he calls the Power Stacker, a modular battery pack system.
At its heart is the Maxim MAX8903 lithium-ion charge controller chip, of which one is provided for each cell. A single cell and MAX8903 with a DC to DC converter for 5 V output makes for the simplest configuration, and he has a backplane allowing multiple boards to be connected and sharing the same charge and output buses.
An infinitely configurable battery bank sounds great. It’s looking for crowdfunding backing, and for that it has an explanatory video which you can see below. Meanwhile if you’d like to try for yourself you can find the necessary files on the hackaday.io page linked above.
Continue reading “Power Stacker, A Modular Battery Bank”
What do you do, when your trusty cordless drill starts to lose battery capacity? You bought it a decade ago and parts are a distant memory, so there’s no chance of buying a new pack. If you are [Danilo Larizza], you strip away the old NiMh cells, and replace them with a custom pack (Italian, Google Translate link) made from 18650 Li-ion cells.
The build is a straightforward one to anyone familiar with lithium-ion packs, but to a battery newbie it should serve as a handy step-by-step description. He starts by selecting a range of matched cells from discarded laptop batteries and adds an off-the-shelf battery management board to keep everything safe. Interestingly he appears to have soldered his wires to the cells rather than the more usual spot-welding, sadly for many of us a spot-welder is beyond our means. It would be interesting to know both the mechanical integrity of the resulting connection and whether the heat of soldering might in some way affect the cells.
Firing up the drill with the new pack is not the immediate success he hoped it would be, the start-up current is so high that the battery management board goes into a fault condition. This situation is resolved with a model that can take more current, and he can take his drill out once more.
If you are annoyed by the rise of cordless tools, you’re in good company. Meanwhile if you lack a spot-welder for batteries, have a look at one of the nicer ones we’ve seen.
[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.
Continue reading “[GreatScott] Tests His DIY Battery Pack On His E-Bike”