Use of a battery pack as opposed to a super capacitor pack

Use of a battery pack as opposed to a super capacitor pack

I realize the the super capacitor industry is struggling. Of course it is. Anything with such industry changing potential is always struggling.

Everyone knows that capacitors can store electrical energy. Unfortunately, regular capacitors can't discharge that energy slowly, they discharge all of their energy in a single flash. Enter super capacitors. Unlike their cousins, super capacitors can not only store energy like their cousins but they can discharge their energy gradually, not all at once. Thus, they work like a batteries. Unlike a battery, however, super capacitors can be charged and recharged indefinitely, no battery life problem. In addition, super capacitors can be recharged in a matter of seconds rather than hours.

I'm so impressed with the range of the Model S. 300 miles is exceptional for an EV. With batteries, some still struggle even with the 300 miles because recharging the batteries for another 300 mile drive will take hours. This means long waits every 300 miles or you have to carry multiple battery packs which is cumbersome to swop. As a second downer, batteries have life spans. The older they get the less charge they hold until they're no longer viable.

It would seem to me, a little homework and brainstorming would make it possible for a super capacitor pack to replace the battery pack with no loss in performance. You could still get the 300 mile range. However, the recharge would only take seconds to achieve. Further, super capacitors do NOT degrade with use.

What would this mean for the EV? Suddenly, the EV can compete toe to toe with fueled vehicles. You can take them on long trips and only spend seconds to recharge and continue the journey. You no longer worry about battery life because super capacitors do not degrade. Now, finally the EV can replace the fueled dinosaur vehicle technology. Fuel independence becomes a reality. With all the massive work that has gone into the Model S and roadster, wouldn't this last breakthrough using super capacitors be worth the additional design and development effort?

Well, it's a thought. I'm so impressed with what Tesla has done so far. I can hardly wait to purchase one of their vehicles when they're available. We love Toyota Hybrids and drive they all the time. We're so glad Tesla has teamed up with Toyota. May their combined efforts be super winners. Thanks, The Phoenix

Timo | July 27, 2010

There are no supercapacitors with good enough Wh/kg or Wh/L to compete with batteries. With 300 mile range you would end up with 10ton car of size of an big truck for five-seater. Or heavier. That is why supercapacitors cannot be used in EV:s (except for perhaps as buffers for very heavy regen braking).

Recharging in seconds is not battery vs supercapacitor problem. There are batteries that can be charged in less than five minutes, but you still can't charge in five minutes. It is problem with currents and volts. You just can't have very high voltage/current connection without making it a safety problem. Calculation: 100kWh battery in lets say 10 seconds. 100kW * 360 = 36000000 Watt connection. Divided by 500 volts you need 72000 Amps. Not going to happen. Raise volts to 10kV (considerable arching problem). Still 3600 Amps. That would require cables that are not usable to humans, you would need robots to move them.

Straight Shooter | July 28, 2010

"Timo" is right.......It is all about the amps. You don't even need high-tech batteries as found in Telsa cars to see that today. Today's AGM batteries, like the one in my boat can be charged at a rate astonishingly high. So high in fact that they used to burn out the anternator (before heat sensors controlled it) that is trying to keep up with the demand. My $700 AGM battery will take 10hrs to discharge at 55amps (like a 24v electic trolling motor on full speed drain) but I could charge it in mere minitues at 2000amps if I could hook it up to that kind of power (which I would not as I'd probably die).

Rather than use esoteric tech like super-conductors, I'd like to see Telsa just offer existing customers an ultra-cheap exchange policy of older batteries when newer tech becomes available in their cars. We would never be 'stuck' with 300mile batteries when the newer 500mile ones come out.

de704 | July 28, 2010

I believe this is what Elon's PHD was supposed to be focused on before he dropped out to form zip2, pay pal and eventually Tesla Motors and SpaceX. Elon has a basic understanding of what you are talking about. If and when it becomes feasible I'm sure Tesla Motors will have their eye on it.

tbw6249 | August 1, 2010

I am 61 and looking forward to retirement in the coming years. I plan to purchase the model S with the 300 mile package. The problem in rural Georgia will be the lack of a charging grid. Short trips will pose no problem, but as someone who routinely drives a 1000 miles plus every week, I would be reluctant to use the model S on many of my business trips unless they were 50 miles out and back. I am amazed at what Tesla has done to this point, and plan to purchase a model S. Thanks for the intriguing posts, as I have gleaned a lot of knowledge reading them.

Brian H | August 4, 2010

by the time you're 65, 1-2000 mile batteries could well be in place. The tech now exists, and apparently doesn't require big manufacturing retooling etc. So keep your toes crossed! ;)

Anonymous | August 12, 2010

In Norway there will be about 2000 charging stations within the end of this yeare! That is more than one for each el-car. You can get them on your GPS-map. Cool.

Paul Koning | August 30, 2010

Phoenix, you're confused about how capacitors work. Every capacitor since the beginning of time can be charged or discharged as slowly as you like.

"Supercapacitors" are simply capacitors with an unusually large capacitance. It used to be that a farad was very nearly unachievable; supercapacitors start at a farad or two and go up into kilofarads (!) But those can get pretty big, physically.

Batteries aren't usually looked at as capacitors, but you can in a way. An 18650 lithium cell is rated as 2600 mAh at 3.7 volts, which translates to 2530 farads, in a cylinder 18 mm diameter by 67 mm long. A comparable supercap is 60 mm diameter by 138 mm long.

Another way to look at it is energy density: Wh/kg. Supercaps are around 6 Wh/kg, while Li cells are around 200 Wh/kg.

So compared to batteries, supercaps have a long way to go. They may get there, but they aren't there yet.

The one thing supercaps can do that batteries can't is very fast charge/discharge.

Brian H | August 31, 2010

Yes, supercaps are useful as a kind of buffer between batteries and motor to handle surges of demand.

mbman88 | July 8, 2013

I think the Original Poster was actually talking about "Nanocapacitors" which literally do have the potential to revolutionize how mobile electricity works. The current Tesla Superchargers take 30 minutes to charge. And I've heard of a new design that could get 10 minutes, which would be exceptional for a battery. However, a nanocapacitor could charge as fast as any capacitor but the energy density is as great as a battery. So in a small timeframe and a lot of heat you could fill up on electricity as fast as it takes to fill up on gasoline. However, I do believe that nanocapacitors are still in the research and development stages.

Brian H | July 8, 2013

Without superconducting cables, they'd be too thick for anything but robotic charging.

TimC | July 8, 2013

At this point, maybe the only practical use of capacitors is in a customized Model S to provide a quick boost of power in a drag race similar to how hot rodders use nitrous oxide with an ICE.

fikret | August 29, 2013

I am looking for an investor to test my supercapacitor!
It's at beginnig so will be cost effective!

My background: over than 30 years as power engineer, a lot of power systems built like power plants (gas fired), wind power plant (biggest onshore WPP, 600MW) etc....

redacted | August 29, 2013

Also: the voltage of capacitors runs between 0 and the max voltage (unlike batteries, which reach low charge state with most of their voltage still available). One has to deal with changing voltages a lot more.

xudamo2008 | February 13, 2014

I'm a representative of a china super capacitor company. We are looking for a chance to board our business. And I believe that our product can be the one that helps us to do some experiments and tests,and build a super capacitor EV.


At present, we have built a large scale production line of supercapacitor, this line makes us have the ability to produce high voltage supercapacitor module. The highest voltage of module can reach 1500V. In the meantime, we assimilate the core technology of supercapacitor through introducing of high-end talent. These measures make the quality and performance of our products exceeding the existing ones comprehensively in the intra-industry. Our market coverage includes a series of emerging industry, such as rail transportation, electric vehicles, wind power, smart grid and military equipment. Our product has been used on a Chinese super capacitor metro program which helped them doing the testing and developing of it.

On the other hand, capacity density of our 9500F cell product is 7.29±0.8% Wh/kg, which is very competitive to lithium battery. I believe that with more contact, we can find what we can achieve through this.

Please feel free to contact me if there is any questions or further requirement.

Thank you.

Kleist | February 13, 2014

@xudamo2008 - Li ion cells Tesla is using are about 245 Wh/kg. Next generation needs to be above 300 Wh/kg... you are about a factor fifty too low.

bonaire | February 13, 2014

East Penn Manufacturing, the maker of the popular Deka battery products and other labeled batteries, is working on a combo battery called the UltraBattery. They use it for grid storage and renewable frequency response for their grid projects and also doing work in EV testing. Probably best for larger truck solutions.

The UltraBattery contains both an ultracapacitor and AGM components. It can take a fast grid charge and discharge during freq. response solutions. Should also prove good for hybridization and maybe even full electric transport solutions like fast charge buses and trucks. Not small enough for cars, i don't think.

xudamo2008 | February 14, 2014

Thank you for the infomation. I know it that currently super capacitor can‘t replace the lithium battery, but there are several part's that super capacitor has it's advantages compared with lithium battery. Bombardier used large banks of super capacitors to recapture braking energy of trains to Riversimple putting super capacitors across the fuel cell in a car. Would it be possible to use it in Tesla start-stop system to save energy? Also, battery will have a bad condition in low temperature (below -20°C) while super capacitor can work well. Would it be a part of the future picture?

carolinagobo | February 14, 2014

Realistically how far we are from a Li-Air or Li–S Battery technology to be produce commercially, 5 years? 10 years? I'll appreciate the answers.

Kleist | February 14, 2014

@xudamo2008 - the added cost of a super capacitor / Li-ion hybrid doesn't justify the small efficiency advantage. In manufacturing cost is king. Elon actually commented on this that he was in favor of the hybrid, but his engineers convinced him that once the battery is big enough the advantages are too small to make a difference.

Brian H | February 15, 2014

You are apparently under the impression you are speaking to the company here. You are not. The posters here are owners, interested persons, and future buyers. You must email or phone the company directly.

huzz1970 | February 15, 2014

There is a "minor" point to any type of capacitor-based storage- the total stored energy is 1/2*(C*V^2), and the total charge is Q = C*V, where C is the capacitance and V is the voltage and Q is the charge. The crux of the problem of using capacitors is that as you pull out charge Q (or current- Q * time), the voltage drops in proportion. You can get the charge out until the capacitor is "empty", but the voltage becomes very low, so you either need some type of dynamic converter that can constantly shift the voltage up to the needs of the motor drive, or the capacitor has to be switched out of the circuit well before it discharges. Such a system can be made, but as noted above the currents will become "interestingly large" as the capacitor discharges. It might be useful for topping on the battery, again with the appropriate circuitry, especially if you want to really jump off the line at a red light (see also the comments from Bonaire above).
There was a comment about the capacitor discharging all at once- this is not totally correct- the capacitor will discharge into the load with an initial current of I = V(C)/R where V(C) is voltage on the capacitor, R is the resistance (actually impedance) into the converter in the motor control or other load. Of course, if you have a short circuit or very low resistance, it could be exciting. Also as noted in earlier replies, the overall energy density of the best capacitors is still well below that in the chemical batteries.
It is true that the capacitor can absorb charge rapidly and discharge rapidly without incurring damage (assuming the materials and construction are good, and the capacitor is not put into an overvoltage condition). This is an advantage to the capacitors. Batteries do exhibit a small reduction in voltage as they discharge and the internal resistance increases, and then they rapidly drop in voltage as the final bits of discharge occur. The exhaustion of the battery is something to avoid because recharging can become a bit difficult as it takes some careful cycling to avoid permanently damaging the batteries while reversing the chemical reactions. This is where Tesla and battery manufacturers and others have spent significant effort to understand the limits of the batteries and charging/discharging conditions. Batteries over time do fatigue as the chemical reactions cannot be perfectly reversed throughout the volume of the cell and some of the cell materials breakdown or form other compounds depending on the chemistry and purity of the materials. This happens in ALL batteries. Panasonic has a pretty good battery group- and just signed on for billions of cells to be supplied to TM, so this is a good endorsement on both sides. Also TM is guaranteeing the battery pack for 8 years.
By the way, this is not a slam on any technology approach- just physics and chemistry. I think it was DuPont- "Better living through Chemistry"....