Discussion
delta0 said:
JonnyVTEC said:
Plus they don’t store much energy…
They were on the concept car for my car, a 2001 Honda Insight.
Capacitors no but supercapacitors yes. Supercapacitors have not been used in production form (vehicles or otherwise). They were on the concept car for my car, a 2001 Honda Insight.
DonkeyApple said:
Capacitors aren't exactly ideal for powering EVs but what is the reason that we haven't considered using them to bridge charging times?
On paper your EV could have a capacitor and a battery to allow you to stop, bang in a slug of electricity to a capacitor quicker than filling a petrol tank and then drive off with the capacitor discharging into the battery to recharge it as you carry along.
Is it cost, packaging or physics that makes this implausible?
Already being tried, but without the batteries.On paper your EV could have a capacitor and a battery to allow you to stop, bang in a slug of electricity to a capacitor quicker than filling a petrol tank and then drive off with the capacitor discharging into the battery to recharge it as you carry along.
Is it cost, packaging or physics that makes this implausible?
https://www.sustainable-bus.com/news/smartbus-turi...
https://chariot-electricbus.com/cmproduct/12m-ultr...
TheDeuce said:
What is the energy density compared to contemporary li-ion?
The best current supercaps have an energy density between a 20th and a 10th of a modern Lithium Ion cell. Things like Graphene and Carbon Nanotubes have the potential to push that up to maybe a third of the density of current Lithium Ion cells but at an enormous cost and by the time they are production ready (if they ever are) one has to imagine batteries will have improved at least to some degree. Edited by kambites on Thursday 16th December 20:09
TheDeuce said:
What is the energy density compared to contemporary li-ion?
Per weight supercapacitors hold 10x more power. However they can’t discharge slowly so they will have lower energy density. The best solution is a combination of the two. Imagine being able to charge very quickly and using the supercapacitors for rapid acceleration and deceleration. Then lithium batteries for the range and absorbing some of the energy from the supercapacitors. Whenever you put your foot down and lose a load of range that could be solved with this as well. Edited by delta0 on Thursday 16th December 23:45
uknick said:
Lamborghini Sian uses them. Admittedly, a car that's not in many people's budget.
Good to know. I hadn’t picked up on that. Hopefully they will trickle down from the high end vehicles into more mainstream ones. They are like a turbo for a hot hatch so I could see them being a big selling point in future. JonnyVTEC said:
Just like a 2010 Honda CRZ, or indeed 2013 when they moved from NiMh to lithium cells and more power … at 34bhp the Sian isn’t really adding more.
It’s being used as a KERS system in the Sian and will take energy from regenerative braking to be used for immediate acceleration. It can dump that power faster than a lithium battery and also it weighs a lot less than batteries do so you can see why they would do it. I imagine they will want to up the power a bit on them eventually though so it can dump down a couple of hundred bhp, that would make a big difference, especially with very little weight addition to the car. delta0 said:
Per weight supercapacitors hold 10x more power.
That sentence doesn't make sense - things don't hold power they hold energy. Supercapacitors can supply roughly ten times the peak power of a LiIon battery of similar weight but have roughly a tenth the total energy capacity.delta0 said:
Per weight supercapacitors hold 10x more power. However they can’t discharge slowly so they will have lower energy density. The theoretical best solution is a combination of the two. Imagine being able to charge very quickly and using the supercapacitors for rapid acceleration and deceleration.
I've added a very important word in bold into your post above ^^^^ :-)The problem is that in practice combining caps with batteries is a expensive nightmare in terms of power electronics. Your traction inverter needs a reasonably stable DClink voltage, and chemical batteries provide that. You high power but low energy capacitors might well, on their own, be able to supply a very high peak pulse power, but you can't feed that directly to your traction inverter or in parallel to your battery because the voltages don't match. This forces you to place DC/DC conversion steps between these sources and the load(s). And if you want high power, then that votlage converter also has to be high power, which means it's big and expensive and complex!
BTW, perhaps the best option is to make the front axle a high peak power device with supercaps, because it only drives hard at low speed (for max longitudinal accel, ie peak tractive effort) or during heavy braking, and make the rear axle a lower peak power battery device (because it provides the long term average tractive effort) and put a single bi-directional DCDC between the two, allowing the front to be charged from the rear (batt-> cap) for performance driving, and regen energy from the front to be moved to the battery (cap->bat) and used for cruising
A modern lithium battery is already powerful enough for a passenger car. People like Tesla are pulling the best part of 1,000 horsepower from their battery. As batteries get bigger on average in terms of energy storage in order to furnish sufficient range, then they get more powerful by default.
Edited by anonymous-user on Friday 17th December 11:57
Thanks for the responses regards power density guys. I already pretty much knew the answer... There's a reason there is billions being invested in new cell tech as opposed to super capacitors.
This goes way beyond EV too. Every aspect of modern tech is crying out for better energy storage. I type this as my phone has just bleeped to ask me for more charge... We need better batteries. Clever stop gap solutions might help a little here and there, but nothing will be as impactful as the next generation of cells will be.
Sadly, we can have no idea if that technology will arrive tomorrow, next year, or in twenty years time. All we can know for certain is the that current EV's will feel like dinosaurs when eventually the new breed comes along and weighs less than ICE and goes twice as far. In the mean time, at least we can say that current li-ion is getting the job done well enough. Driving an EV today isn't a struggle - even if we can imagine it being improved in the future. The same way we all lived very happily with tapes ahead of CD's
This goes way beyond EV too. Every aspect of modern tech is crying out for better energy storage. I type this as my phone has just bleeped to ask me for more charge... We need better batteries. Clever stop gap solutions might help a little here and there, but nothing will be as impactful as the next generation of cells will be.
Sadly, we can have no idea if that technology will arrive tomorrow, next year, or in twenty years time. All we can know for certain is the that current EV's will feel like dinosaurs when eventually the new breed comes along and weighs less than ICE and goes twice as far. In the mean time, at least we can say that current li-ion is getting the job done well enough. Driving an EV today isn't a struggle - even if we can imagine it being improved in the future. The same way we all lived very happily with tapes ahead of CD's
TheDeuce said:
We need better batteries.
Other things too.Hydrogen cars that use a piston engine are coming through- but how to store the hydrogen?
How does the weight of a hydrogen tank compare to that of batteries? Or can a softer tank be used?
Fuel cells might be able to use capacitors instead of batteries for load levelling.
Some EVs are more efficient in miles per kwh than others - size, weight and aero.
TheDeuce said:
Thanks for the responses regards power density guys. I already pretty much knew the answer... There's a reason there is billions being invested in new cell tech as opposed to super capacitors.
This goes way beyond EV too. Every aspect of modern tech is crying out for better energy storage. I type this as my phone has just bleeped to ask me for more charge... We need better batteries. Clever stop gap solutions might help a little here and there, but nothing will be as impactful as the next generation of cells will be.
Sadly, we can have no idea if that technology will arrive tomorrow, next year, or in twenty years time. All we can know for certain is the that current EV's will feel like dinosaurs when eventually the new breed comes along and weighs less than ICE and goes twice as far. In the mean time, at least we can say that current li-ion is getting the job done well enough. Driving an EV today isn't a struggle - even if we can imagine it being improved in the future. The same way we all lived very happily with tapes ahead of CD's
Given the typical length of investment cycles being around ten years, the typical length of time for bringing an extraction plant on stream (up to 15 years from start of finance raising to profitability) the amount of money going in does tend to make it clear that no significant change is anticipated for very many years. Since the late 90s, retail gamblers have been hurling their savings at any penny share entity working on graphene. As of yet to no avail and pretty much to the point that we now just walk out of the meeting if it transpires that someone's been silly enough to entertain a discussion on it. It'll happen at some point but it's for dumb money to bankroll, smart money is going to the dumb tech that actually works now. This goes way beyond EV too. Every aspect of modern tech is crying out for better energy storage. I type this as my phone has just bleeped to ask me for more charge... We need better batteries. Clever stop gap solutions might help a little here and there, but nothing will be as impactful as the next generation of cells will be.
Sadly, we can have no idea if that technology will arrive tomorrow, next year, or in twenty years time. All we can know for certain is the that current EV's will feel like dinosaurs when eventually the new breed comes along and weighs less than ICE and goes twice as far. In the mean time, at least we can say that current li-ion is getting the job done well enough. Driving an EV today isn't a struggle - even if we can imagine it being improved in the future. The same way we all lived very happily with tapes ahead of CD's
It would be a genuine 'black swan' event that delivered a commercially viable, mass produced new solution that was smaller, lighter and released the biggest shackles to mankind in the 21st century.
If we just spend a moment considering the existing tech that would be manifestly changed in its use and capabilities of it were possible to store power efficiently then you begin to see that such a breakthrough will change the world more than the internet did or smart phones. It is a truly momentous event in waiting from micro tech to massive industrial solutions. 1859 was when Gaston Plante invented the rechargeable battery and in 160 years it is just about the only technology that genuinely hasn't moved forward in a major step change. In 2021 we are still utilising the same rules of chemistry to produce an extremely large, heavy and low energy density battery. Only hype and spin prevents the clarity of seeing the absence of significant change.
100 years on from really, really crappy petrol out competing batteries as a means to power a car and in 2021, petrol remains superior as a mechanism for storing energy for a car. The absolutely farcical complexity of getting petrol from several miles below the Earth's crust into a car still cannot be bettered by a battery despite the magnitudes of superiority the electric motor has over the comically complex and inefficient internal combustion engine.
However, like you point out with our smart phones, the battery isn't very good at all but we have all adapted around that fallibility to the point that it's genuinely a non issue. We charge our phones at night, we top them up when out and about without giving it a second thought. Those of us who have lifestyles that keep us away from USB sockets for long periods of time have adapted and found other solutions to charging.
The same is true with batteries in cars. They might be crap but the reality is that they are already good enough to work. There are very few people in the U.K. who couldn't make an EV work if they had no choice. The vast majority of humans wake up each day and simply do exactly the same as they did the day before. They've even made films about the repetitive mundanity of almost all human life. At the same time all these humans adapt instantly and almost without any thought to changes and evolutions in how their environment works.
The reality is already clear, has been for a few years and is exactly as predicted: in the main, excluding the apex shoppers who have to have whatever is new in order to find any happiness and confidence in life, people will simply switch to EVs based on the price being at their spending level and refuelling being easy and cheap. All we are seeing today is the start of the millions of households who know they never need to go a long distance with a particular car and are also unlikely to ever need to refuel away from home. We've had a few years of obsession over the hypermiling, 1980s travelling salesman that really just hasn't existed for years. There aren't millions of blokes ploughing hundreds of miles a day in a Vectra or Mondeo any more. All those blokes are now retired and just driving to garden centres, country pubs and doing tens of identical local journeys. And those who still have no choice but to travel long distances will be among the last to switch in 15-20 years time if their employers don't create private networks for them which many are to facilitate staff movement between regional business units and many business are to facilitate customer and partner EV needs.
While these tens of millions of suburban runabouts are slowly switching to EV as more and more EVs hit consumer budgets all these private remote charging networks that they don't really need will be growing, Li tech getting marginally better and maybe new Li tech such as solid state coming on stream. The more easily scared humans will become less terrified as the change becomes more boring and less new. Some of the most rabid antis will have their statistically inevitable conversion to being rabid enthusiasts full of hate for what they once were. People will naturally come to terms with the reality and mundanity of their day to day existence. They'll still post all their fabricated billionaire, action hero tripe on social media, still rush to tell anyone who'll listen just how dynamic and awesome they are as a human but they will have long since accepted that the reality is that they drive to the exact same place on the exact same day, at the exact same time and do the exact same thing and that their EV works perfectly as a result.
There will be no issue with the Grid because the Grid will price consumers away from the peak hours and consumers will follow the pricing without a second thought.
There will be no issue with fast charging because pricing will deter those who really have no need of it.
Grazing will become as common place as Nectar points. People will plug in everywhere they stop to claim their reward for being special and important.
The same people will be sitting by the same roads waiting for someone to arrive with some fuel for them.
Employers and landlords will add endless numbers of chargers to facilitate business and to avoid tax penalties. Employers will also evolve their roles so that they work within the remit of EVs. Their staff will have to drive EVs so the employer will have to ensure work charging so as to not legally discriminate against their poorer employees and they will have to use more local labour to avoid the uncompetitiveness of sending a work unit on a 400 mile journey that would involve hours of zero productivity. No employer wants to be paying a worker to be sitting in a car doing no work if they can avoid it anyway. It's exactly why the number of those jobs has fallen off a cliff in recent years.
For many people on this planet, switching to EV is an impossible dream without a step change in pricing and technology. For a small island like Britain that is one of the wealthiest places on Earth and where workers, employers and lifestyles can easily adapt almost without sentient thought, it is a piece of piss that the vast majority of people could do today if the initial purchase price were down to their desired level, which will eventually happen even with Li batteries.
My pondering around capacitors was whether they could become one of the transition bridges over the next 20 years until Li battery tech is replaced to facilitate a 'splash and dash' fudge solution where a user can dump 50-100 miles into a car very quickly and drive off with the capacitor then releasing that energy into the Li pack which the motor draws from. Such a solution would come close to doing away with the hybrid phase that awkwardly sits between pure ICE and pure EV.
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