I am in the lucky position to develop the firmware for the device / not being the electronics guy
The reason is a mismanaged project. Power budget on a CR2032 is tight and initially a supercap with much bigger capacity was planned. The company producing those went out of business and people were forced to somehow get it to market, working. We did, but now those new tantal cap problems arrived.
I got this great memory from electronics class in high school, we were measuring some circuit which included an electrolytic capacitor, using an oscilloscope. All of a sudden I hear a panicked voice from the back of the class saying "it's growing, it's growing... turn it off... turn it off!" and my other classmate replying "but it _is_ off!" which was immediately followed by a very loud bang.
I turn around and see my two class mates looking shocked and confused, covered in fine fur all over their upper bodies, along with the desk.
Never got around to understanding just how they managed it, but they most certainly did manage to blow up that capacitor in a spectacular way.
The fun is that capacitors work even when power is off, so if they had several caps together and one was the wrong way round or the power supply was off but not disconnected OR the capacitor was already charged beyond a point of no return, it'll blow.
While they look fairly harmless, one should also never forget that capacitors are the most dangerous part of any electric circuit; they don't become safe if power is off and they have no limit to their current other than "what the wire can do", which is usually northwards of "the wire evaporates".
I've experienced various caps burn their legs and solderpoints in less than a millisecond without warning once a short was realized. And on top of that, the huge currents running through wires not intended for that will usually cause quite a bit of inductive backlash in nearby components.
I've worked with capacitors that were designed to dump their charge in a few us. You really do not want to mess with that stuff without proper precautions, nothing scares me more than a couple of hundred volts power source with an Ri too low to measure. You need to forcibly restrain your cabling or it will jump all over the place during a discharge.
Heh... Recalling a demonstration by an EE prof way back when. He had the bank of capacitors charging up on his desk, and was writing on the blackboard the equations of how much energy was stored. Hand raised in the back of the room. "Uh, Dr. Miagawa, I think you slipped a decimal point there." Prof looks over his work again, says "Oh, dear" unplugs the charger and backs away. He tapes two meter sticks together with a screwdriver on the end to discharge his little electrobomb. WHAMO, screwdriver vaporizes.
I'm pretty much convinced this was not a mistake, it was a "Be really CAREFUL with this stuff!" object lesson.
Those dry out. They're there to help a tri-phase motor run on single phase power and that's massively abusive to the caps. They tend to get hot enough that the electrolyte slowly evaporates in spite of a lot of effort to seal them. If you look carefully you'll find a little 'x' somewhere in the plastic bottom, that's an overpressure relief. If it is distended outward that cap is about to die.
You can blow them quite nicely if you manage to create a magnetic field inside the capacitor that exceeds the strength of the beaker it is contained in. That's a lot of bang for your buck, please don't try this at home. The good thing is most capacitors have an internal resistance and inductance high enough that this isn't a problem. But with capacitors that are made for very fast discharge (such as the ones used in old school xenon flash equipment for studios) you may be in for a surprise.
Purposefully weakening the container can bring this sort of behavior out at lower levels.
Start small. 1000 uf and work your way up from there. Stay away from anything that looks like it is mechanically reinforced to make the housing stronger for mounting purposes or mechanical stability. Those are bombs. Don't come crying ;)
Capacitors generally release all of their energy all at once if you short them, which is very bad.
Gasoline is flammable, but it needs the right fuel air mixture to actually explode. Car fires are relatively common, but as far as I know car explosions are not.
So wait ... we need something that can rapidly absorb power, and rapidly disperse power. And the criticism is that this can explode ? An explosion is simply rapidly dumping energy in something that's a gas or about to become a gas. Not that other forms of rapidly dumping power are any less damaging, btw.
So, yes, they can explode. That's actually pretty much the point.
One of the primary arguments that I hear for them is how much safer they are than Lithium Ion batteries. Being able to explode (even if this is actually unlikely) greatly weakens that purported advantage.
(I do not believe this will actually be a primary impediment to adoption of either Lithium Ion or Super Capacitors)
EEStor was lying through there teeth and never allowed anyone outside the company to directly measure ED, just gamable proxies for ED (such as capacitance).
Not only that, but this article shows a major warning sign of a fake breakthrough: [massive] understatement of the potential impact.
This company claims a hundredfold improvement in capacitor capacity! And yet they also claim to be drop-shipping from a Chinese company I cannot find anywhere but their website. Where is the Chinese media to stump for what would be quite possibly the greatest discovery in China since gunpowder? Where are the physics papers discussing the necessarily entirely new mechanism of storage in this device?
Seems like an eternity we've been hearing/waiting for super capacitors to become a thing. They seem to be the final puzzle piece in EV adoption. Not having to wait hours to "fill up" at the recharging station will be huge.
The article talks a bit about this, and fast charging seems to bring some problems with it, though:
_Theoretically, these power capacitors could be wrapped up into a big battery pack and used to power a long-range, super fast charging EV. The high-power versions can charge to 75 percent in five minutes, for example. But Verhulst doesn't believe this tech will flood the automotive market. "You need a charger that can handle it," he tells us. "A 10 kWh pack charged in five minutes means you'd need a 100 kW charger. If you then go to the big ones, say a 100 kWh battery, you'd need a megawatt charger. That's a lot. That's a whole power station. So scalability is still an issue."_
Electrify America / ionity / Tesla superchargers these days already output 250-350kWh. You could also use those super capacitors in the charging station itself to level out demand.
Using them in the grid itself is an even bigger aspect, either for simple storage that can act as a peak power plant or to act like a high frequency energy trader.
Battery backed renewable power is competing primarily with natural gas in being able to absorb and release power. They have to last 10-20 years. Batteries heat up when you charge or discharge them, which causes lifetime decrease and efficiency losses.
If these capacitors have lower internal resistance (and it sounds like they do) and last reliably for 10 years... yeah, I can see these being a next generation alternative to battery based storage at the grid level.
If they can manufacture them in a rectangular plate kind of form factor like a cell phone battery, I imagine there could be a huge benefit there. I think people would pay a premium to be able to charge their phone to last for 10 hours in 12 minutes (50C charging rate).
This is exciting. That they're in production and being tested by outside partners is a huge validation point that this is real.
These seem to be a combination of capacitor and battery - not pure capacitors. So I think they will have some downsides of batteries like a more limited cycle life than a pure supercapacitor. The article doesn't seem to touch on the downsides which is common with this kind of reporting.
Supercapacitor is an ambiguous term that just means "a capacitor with properties somewhere between a common capacitor and a battery". They've been a thing for a long time and they've been getting more and more "super" every year. They're just really expensive and only practical in highly specialized applications so you don't hear about them very often.
Sort by price descending to see some of the more interesting ones. The cheaper ones are still called supercapacitors but the delineation becomes a little meaningless at that range since regular capacitors have also improved significantly.
You don’t need a power plant to charge, you just need a bigger capacitor sitting at the gas station that’s been filling up for a while and ready to dump into your car.
And then you'll leave the station and stop/go/hills/regen further "flexes" a similar dedicated powercapacitor bank onboard (separate from the Li/Co/Mn/Ni long term reservoir which is expected to contain thousands of cycles whereas capacitors are tested in the millions).
If you're highway bound often this may mean faster decay of battery throughout the decade because of which side gets cycled.
I thought brake regen to battery was already really high efficiency. Hm, apparently it's 60-70%. capacitors might add a couple percent but I bet there's inevitable heat loss from running the motor backward.
I think parent is more getting at component lifetime. Every charge/discharge on the batteries is a bit of their lifespan gone.
Although I was under the impression that the impact on lifespan is much greater the deeper you cycle the batteries, so it might be better to be perpetually topping them up.
Yeah deeper cycle reduced life - highway static travel speed would idle onboard capacitor bank.
You make me wonder if it would be better to charge every hundred miles in your 250mi range rated EV as a way to preserve long term battry health on a long interstate road trip.
Whatever percentage we can get out of brake (or downhill coasting) regeneration should be routed in&out of capacitors as often as possible in order to preserve the long range long term storage battery.
Lithium batteries don't explode. They melt down and then catch on fire when pierced. You have plenty of time to get away, just don't get stuck right next, under or above them.
> The power-focused variants were delivering densities of 80 and 100 Wh/kg, and were charging and discharging at 10 and 20C.
I don't think it is Celsius, and Coulombs (which would be the correct SI unit) doesn't really make sense. Some number of Amps would make sense, but 10 or 20 isn't very impressive.
"A C-rate of 1C is also known as a one-hour discharge; 0.5C or C/2 is a two-hour discharge and 0.2C or C/5 is a 5-hour discharge. Some high-performance batteries can be charged and discharged above 1C with moderate stress."
Racing drone batteries can be charged around 4C and discharged at close to 100C (Unsure how many of those C is marketing), but then I think they safely qualify as high stress..
Seems to be C-rate[1], a unit specifically for battery discharge rate. Funny enough, the wiki article does mention disambiguation between it and Coulombs.
Something seems fishy. Capacitors voltage versus charge conforms to the equation C= 1/2CV*V
with half the voltage you have only 25% of the charge remaining!
With a battery, you have the 2 half cell potentials that sum to the rated voltage. As you discharge, this is a flat line voltage until the charged element is depleted and it goes to zero, (discharged).
This has the ring of a scheme to get investor $$
Agreed. Stories like this keep popping up, because this is something the whole world desperately needs. EEStor was one of the previous claimants to the title, but they flew by night.
After so many disappointments, I'm down to "Let me know when I can buy one at Fry's, until then, I am not holding my breath."
It's weird for someone selling an ostensibly breakthrough EV energy storage system to say that he's mostly focusing on plugin hybrids. Batteries aren't the major contributor to cost or complexity in PHEVs.
But if the cost is higher than lithium battery cells, their better discharge rate, (perhaps) regen efficiency, and cycle advantage would justify the premium in hybrids.
If I read the article in the worst possible way it suggests the hybrid capacitor stores 260 Wh/kg and produces 300 W/kg.
The Tesla battery stores 272 Wh/kg and produces 207 W/kg.
So this suggests the hybrid capacitor would charge 1.4 times faster.
Next question is the price, the article doesn't give a straight-forward answer other than that it's significantly more expensive. In theory (no hard proof) the hybrid capacitor would last longer.
From what I keep hearing, current EV acceleration is limited by the battery discharge rates. I haven't seen anyone talk about creating a multi-tiered (hybrid) battery.
Have a comparatively small capacitor sit as a "battery cache" for short (5-10 second) bursts of acceleration, and let the battery be the slow but efficient & steady main energy store. This would mitigate many potential downsides to capacitors (e.g. cost, leakage, energy density, etc etc).
Modern EVs accelerate incredibly quickly. Tesla uses the 0-60 time as a main feature of their marketing.
Once you have enough battery cells, a large power draw (acceleration) or power feed (charging, deceleration) becomes a very small amount of current for each cell.
> From what I keep hearing, current EV acceleration is limited by the battery discharge rates
Acceleration today is mostly limited by available traction. It's not at all clear that a liveable car could get appreciably faster acceleration than we have today without a breakthrough in tire technology.
Yep, and why every supercar's 0-60 time is limited to about ~2.6s these days. Also why tesla is claiming to be able to achieve <2.6s only with the cold gas thruster "SpaceX" package, they're no longer solely relying on the tire traction.
The exact number wasn't really the point + elon has a history of releasing high performance spec's before the actual technology is ready. Maybe they have special tires in the works, but the rubber that's on the market today can't do that
But friction is dependent on the pressure between the contact patches. More area of contact reduces the pressure per unit of area. So you’d need more pressure on said tires without augmenting mass (because then you’d need yet more friction to accelerate that mass, that’s why wings are a thing, more pressure on the tires without adding mass that you’d have to turn accelerate.
Problem with wings is that they not only add drag but they are not affecting anything at launch. Maybe if you had a big electromagnet under the car and a steel path under the asphalt.
Some race cars [1] put fans under the cars, sucking upward. This effectively created a vacuum under the car and allowed it to stick to the road pretty well. It was more for cornering fast than straight-line acceleration. But modern race cars to use aerodynamic tricks to create downforce, but only to keep the car on the ground at high speeds.
But you won't be turning that car around any time soon. The Flintstones notwithstanding it isn't particularly clever to have your tires run the width of the car because the inner and outer radius during a turn will cause the tire to wear rapidly. You could cut the width-of-your-car tire into a lot of slices I guess but that would be mechanically quite complex and you'd still have to drive it somehow.
You get into the limits of being able to transfer the rotation of the axle to the tire patch.
Mental picture time, if you will:
1. Axle spins, which rotates the metal wheel
|> since the metal wheel is metal to metal with the axle, we will consider it to be one unit, even though technically, it is not
2. Metal wheel rotates the part of the tire near the rim
|> There is only so much force which can be applied to join the tire's bead to the metal of the wheel. "Bead locking" can be done, but this is esoteric and, at least in the US, is mostly not legal for road-going vehicles. Also, the amount of space necessary for bead locking components is a complex challenge for the passenger car wheels, and is usually reserved to far larger wheels found in off-road-like vehicles.
3. The tire rim has to transmit the rotation to the tire contact patch, which happens via the tire sidewall.
|> This sidewall has to stay flexible otherwise the ride would be nigh impossibly jarring. Check videos of sidewall flex of drag tires for a practical example of this, a-la https://youtu.be/rw3LE78gwhg
There are plenty of other things in play, top, but these are the big limiting factors.
The new Tesla roadster coming soon(TM) does 0-60 mph in 1.9 seconds, and the quarter mile in 8.8, which is staggeringly fast even by ultra car standards. People that spend years and hundreds of thousands of dollars on their dedicated drag car never get that fast. I don't believe there's ever been a production car that runs in the nine second range, let alone into the eights.
I believe with EVs, traction is not as much of an issue because the computer can adjust the torque output 1000 times per second, unlike an Internal Combustion Engine which takes eons to react and change it's power output. Obviously off the line it is, but certain as you get moving more you can dump a lot of torque into sticky rubber.
Tesla are having a "battery day" soon, and I for one suspect their new batteries (maybe just for the new Roadster, maybe for all their cars) will be some kind of hybrid capacitor, or at least have some of their capacity does that way.
That's right, nobody really needs this, but the point of the Roadster V2 isn't to satisfy a need, it's to eradicate the perception that gasoline cars are better performing. By building a supercar that will humiliate all the Porsches and Ferraris, with no hope of gasoline cars remotely in the same price range ever being able to compete (unless they go hybrid?), Tesla will catch a lot of press. A new generation of kids will grow up with the clear perception that electric cars are superior technology. They will have Tesla Roaster posters on their walls instead of gasoline cars. The roaster is very much an expensive PR piece, but it will change the world and accelerate the transition to renewable energy in a meaningful way. Perception counts.
AFAIK, usually Tesla reports performance numbers conservatively. For example production version of Model Y has longer range than what it was announced to have. Why would this be any different?
I think that hybrid buses have been doing this for a long time. They have big supercapacitors on the roof which buffer the rapid charge from regenerative braking and use it to recharge the battery or provide energy for acceleration.
The problem I've always seen with supercapacitors is that their leakage current usually seems to increase as their ESR drops. So as they gain the ability to charge/discharge quickly, they lose the ability to hold charge over time.
I wonder if there are ways to mitigate that, but there are other problems like poor handling of high temperatures and mechanical vibrations / shocks; both are difficult tradeoffs for automotive parts.
They are proven solutions for buffering energy in EVs, but it's harder to justify the cost/weight in light passenger vehicles. That's why hybrid solutions like this are exciting.
These look cool - does anyone know if they have two or four dielectric layers? I can't quite tell from the article. IIRC Supercapacitors use four while traditional capacitors use two, and I feel like the self-discharge/ESR tradeoffs of supercapacitors might have a lot to do with the finnicky EDLC technology. If they've managed to make traditionally-structured capacitors with the Farad ratings of supercapacitors, that would be very cool.
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