Author Topic: charging up your electric car in 10 minutes - supercapacitors  (Read 3002 times)

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Offline digsys

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #25 on: March 09, 2018, 04:32:52 pm »
Quote from: BrianHG
If swap-able batteries came to be available in mass, can you just imagine the con re-furbished junk which will be guaranteed to eventually end up in the market.  1 day you have a good battery.  The next, you wont make it back home, though the gauge says you should be able to.  It will be the stupidest choice a consumer can make since they wont be able to confirm exactly what distance and wattage they are getting.  I prefer having a battery pack design which exceeds the available amount of driving range you can do in 1 day.
Better place tried to push his "battery swap" model all over the world (incl Australia), and it failed everywhere. I am proud to be involved in a
team that helped rid them from OZ. Apart from what you point out, the logistics of moving 1,000s (eventually) of battery packs, and these will be huge,
around the country, to all "charge sites" is monumental, not to mention the large volume / weight of the packs. Which also, places severe limits
on vehicle design / shape / loading. Trying to standardize all makes / models would be impossible.
Easy replacement though is still VERY desirable, the packs we design can be swapped out as easily as a normal battery. They are usually app
2-3X the size, but we make sure they don't exceed ~20Kg each. It means, should something go wrong, they can be easily exchanged a station.
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Offline BrianHG

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #26 on: March 09, 2018, 04:33:50 pm »
I am pretty sure that hot swappable batteries would end up tracking their own performance. An inbuilt micro probably. The car has to know the available mileage. It can learn that with a single installed battery, but for swappable batteries, the information has to come with the batteries.

You would think there would have to be some kind of rules, such as when a battery pack drops to 80% capacity, it can no longer be recharged by a charging station - it has to be returned for recycling.
Ahem, haven't you heard of re-furbished printer cartridges with manipulated serial proms.  Those messed up cartridges which screw up your printer due to either ink eventually getting clogged in the print head, or, color toner speckles appearing all over your printout after a weeks use.  Do you honestly believe these batteries wont be hack-able.

And don't think this cannot happen with fuel.  Locally, a gas station was caught adding water to their fuel, just enough to make a few extra $, but, motors could still burn it.  Years ago, I was stuck going to a no-name gas station and my engine got f---ed and sand was found in my gas tank.
« Last Edit: March 09, 2018, 04:35:34 pm by BrianHG »
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Offline digsys

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #27 on: March 09, 2018, 04:42:21 pm »
Quote from: amspire
  ...  Obviously, if you are going to use capacitors, you design for the voltage swings ....
Designing a motor controller to work at min ~96% efficiently (ours is 98.5% min), over a wide power band is tough enough with a 20% Vin
variation, to design it at the voltage swings seen with a capacitor source is near impossible (we've looked at the idea). Maybe one day.
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Offline julianhigginson

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #28 on: March 09, 2018, 04:44:23 pm »
For the near future I really like the idea of cars like the chevy(holden here) volt... full electric car, with a petrol motor that is purely a generator. But for some reason, electric cars with petrol generators just aren't that popular...

For short drives you stay pure electric, and recharge off the grid where possible. As you start to extend your range, the motor kicks in to charge up the battery, which then keeps you going... I'm not sure why this hasn't been so popular? seems like a pretty good idea to me. I understand you need extra stuff (ie a motor and a petrol tank and a generator) but it means you can use existing infrastructure where needed, and the petrol motor can be far more simple than a car engine - it just needs to run at an optimum rate to get good electrical efficiency into the batteries. And no gearbox needed.

I like it better than toyota's hybrid thing.. that just seems really complicated. And you are 100% powered by fuel still.... Though admittedly it gets pretty amazing fuel efficiency...
 
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Offline amspire

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #29 on: March 09, 2018, 04:44:53 pm »
I am pretty sure that hot swappable batteries would end up tracking their own performance. An inbuilt micro probably. The car has to know the available mileage. It can learn that with a single installed battery, but for swappable batteries, the information has to come with the batteries.

You would think there would have to be some kind of rules, such as when a battery pack drops to 80% capacity, it can no longer be recharged by a charging station - it has to be returned for recycling.
Ahem, haven't you heard of re-furbished printer cartridges with manipulated serial proms.  Those messed up cartridges which screw up your printer due to either ink eventually getting clogged in the print head, or, color toner speckles appearing all over your printout after a weeks use.  Do you honestly believe these batteries wont be hack-able.

And don't think this cannot happen with fuel.  Locally, a gas station was caught adding water to their fuel, just enough to make a few extra $, but, motors could still burn it.  Years ago, I was stuck going to a no-name gas station and my engine got f---ed and sand was found in my gas tank.
Of course they will be hackable. Just the same at petrol pumps can be fiddled with. You can have big penalties and make it hard though. Every time that battery is charged, the data can be required to be recorded - maybe to a distributed blockchain database. If one charging station has all its batteries increasing in capacity by 50% suddenly, then they get audited and the batteries they are offering are tested. Fraud is a criminal offence - they can go to jail.

I do not what what the system will be, but there would be a system. It wouldn't work otherwise.
 

Offline Psi

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #30 on: March 09, 2018, 04:47:20 pm »
TOPIC: charging up your electric car in 10 minutes - supercapacitors

I can start my car engine in ~300ms of cranking (when it's warm) because i replaced my car battery with supercaps.
The voltage doesn't drop under 400A load, so the voltage at the starter motor is the full 13.8V instead of like 8V
It cranks over SUPER fast.

Does that count?
« Last Edit: March 09, 2018, 04:49:20 pm by Psi »
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Offline julianhigginson

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #31 on: March 09, 2018, 04:57:48 pm »
as for a 10 minute charge on a regular electric car... yeah...

Given a 100kWh battery (tesla model s?) that's going to need charging at 600kW, before you even consider charging efficiencies...

That's some insane voltages or some insane currents (or both!) across/through the charging connector.

Come to think of it, I'd love to see what a pluggable connector for applying 600kW to something outdoors would look like. I imagine it'd be pretty big.
 

Offline digsys

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #32 on: March 09, 2018, 05:09:53 pm »
Quote from: julianhigginson
For the near future I really like the idea of cars like the chevy(holden here) volt... full electric car, with a petrol motor that is purely a generator ....
As you start to extend your range, the motor kicks in to charge up the battery ... seems like a pretty good idea to me.
It is an excellent idea, and been around for ages .. diesel electrics .. in trains, trucks, mining machinery etc etc etc
All the EV makers have had it as an option (or planning it), and it is usually an all-in-one unit (a petrol tank swap-out?).
And as you say, it is EXTREMELY efficient, both due having a total EV drive, plus the generator is optimized JUST for charging.
The bonus is, it alleviates range anxiety. It's around, and still being developed, not sure why it isn't mentioned more though

Edit: found this, good article - www.bioturbine.org/Publications/PDF/microturbine-01-HILTECH.pdf
« Last Edit: March 09, 2018, 05:13:03 pm by digsys »
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Online Berni

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #33 on: March 09, 2018, 05:19:24 pm »
TOPIC: charging up your electric car in 10 minutes - supercapacitors

I can start my car engine in ~300ms of cranking (when it's warm) because i replaced my car battery with supercaps.
The voltage doesn't drop under 400A load, so the voltage at the starter motor is the full 13.8V instead of like 8V
It cranks over SUPER fast.

Does that count?

Now that is the correct use of supercaps.

Tho in Australia i don't think there is that much use for it since it doesn't get all that cold. Over here in Europe that would be more useful. If you have a big diesel sitting outside in -15°C all night and its battery id a fair few years old you will get some seriously slow cranking out of it. To the point where you can easily coun't how many compression cycles the engine did while you pray that it will fire up.

Lead acid batteries really get there internal resistance shooting up when they get very cold. The diesels are not only difficult to turn over due to there high compression ratio but also use glow plugs on cold starts to help it ignite and those take around 100A for a few seconds after turning the key after all that the battery has to then crank it.
 

Offline Psi

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #34 on: March 09, 2018, 05:24:01 pm »
It's not cold here either, i only did it for fun :) and i was sick of replacing car batteries every 2 years.
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Offline amspire

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #35 on: March 09, 2018, 05:26:33 pm »
as for a 10 minute charge on a regular electric car... yeah...

Given a 100kWh battery (tesla model s?) that's going to need charging at 600kW, before you even consider charging efficiencies...

That's some insane voltages or some insane currents (or both!) across/through the charging connector.

Come to think of it, I'd love to see what a pluggable connector for applying 600kW to something outdoors would look like. I imagine it'd be pretty big.
The present 120kW Tesla Supercharger is something like 480v and 250A.

The 1MW Megacharger for the trucks I gather will probably double the voltage - so basically is will be 1000V at 1000A. The connector has 8 big pins, so that would be 4 circuits with 250A each. That would mean 8 copper cables of something like 12mm each. They could go thinner if they don't mind the cable getting warm. It will be heavy.
 
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Offline julianhigginson

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #36 on: March 09, 2018, 05:39:22 pm »
It's around, and still being developed, not sure why it isn't mentioned more though

yeah, It just seems really rare in practice.

I was having a think about what my next car might be the other week. I really want to move away from petrol (not like my standard western lifestyle doesn't consume plenty of petrol in supply chains anyway, but I would like to do what i reasonably can...)

But as much as I'd like a full electric car I live far enough away from where I need to get to and back from sometimes, that most EVs would not be an option. I was looking for anything to do the job without ending up in a toyota hybrid (which isn't THAT bad an option, though it's still entirely a petrol powered car)

I found the Volt, but that's not even got a current model in Australia any more. It was withdrawn from the market after just a few years of very low sales. Which is sad, because the reviews seemed pretty positive.

I haven't found any other generally available electric car with range extension this way in Australia.
 

Online Berni

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #37 on: March 09, 2018, 05:39:44 pm »
It's not cold here either, i only did it for fun :) and i was sick of replacing car batteries every 2 years.

Well a car battery should certainly last longer than 2 years, tho the Australian heat likely is not good for those batteries ether. But im pretty sure a supercap can extend the life of it by 3x easily. Perhaps the batteries even age slower if they are not repeatedly exposed to those large discharge currents.
 

Offline james_s

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #38 on: March 09, 2018, 05:50:13 pm »
Yeah 2 years does seem awfully short. I just recently replaced the battery in my car that was more than 10 years old, I've had several batteries last that long.
 

Online Berni

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #39 on: March 09, 2018, 08:52:06 pm »
It is a question however how do the giant lithium batteries in electric cars perform after 5 years of use. Its pretty common for batteries in phones and laptops to really loose a lot of there capacity over a few years of constant cycling.
 

Offline NANDBlog

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #40 on: March 09, 2018, 09:46:38 pm »
I was testing large supercapacitors some 2 years ago. It was about half a kilogram, and some 1000s of Farads. A half kilogram capacitor had about the energy of a AA NiMH battery.
This could work for a bus line, where stops are every few hundred meters (in fact, the capacitors were for this application) but not for an electric car.
The article Homer linked to states that the super capacitors are not intended as primary storage but just to handle the big current surges during accellerating and braking. It makes sense to use super capacitors there in order to prolong the life of the Li-ion batteries. I don't see super capacitors as a primary energy storage any time soon because their energy density is way to low.
You are right, I havent read the entire article, as it seemed like those general articles, which only concentrate on one issue.
I see that they want a hybrid capacitor-battery storage. My question is: Why? They claim that:
"Supercapacitors don't store as much energy but their response is instantaneous. So a supercapacitor could handle acceleration and energy recovery under braking - taking care of the stressful part of a battery's life - possibly doubling or tripling a battery's life expectancy."
So for example a Prius in microcycling can handle hundreds of thousands of cycles. Breaking and accelerating is microcycling, on a full electric car it is even less impact. A battery pack large enought to handle the range easily can handle the peak currents both ways.
And of course the supercap has nothing to do with the 10 minute charging.
 

Offline cprobertson1

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #41 on: March 09, 2018, 10:21:41 pm »
It is a question however how do the giant lithium batteries in electric cars perform after 5 years of use. Its pretty common for batteries in phones and laptops to really loose a lot of there capacity over a few years of constant cycling.

This self-reported data gives you an idea of how the range degrades with time - obviously this contains confounding factors.

Nissan guarantee their batteries at 70% capacity after 5 years/60'000 miles (but I don't know how that would overlap with battery leakage figures).

It depends on the climate as well - Nissan were having problems with battery degradation in hot states, so it might be worse in some cases - while data collection on other cars suggested they might still have between 80 and 85% capacity after 100'000 miles.

New batteries are also prohibitively expensive in some cases - £100/kW (£6'500-£8'000 for a few typical battery assemblies that I had a look at) seem fairly common from a cursory google search.
 
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Offline woodchips

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #42 on: March 10, 2018, 07:21:58 am »
The snag with capacitors, super ones or not, is that they lose half the charge energy when being charged, Q=1/2CV^2. This is rather inefficient.

Lead acid batteries are not at their best in very cold conditions. But, by taking current from the battery and hence warming it up you will get more than the energy taken to warm the battery. The warm energy level is still in the battery, just that the cold stops it being used. Sneaky. So using the heater plugs is a good thing, in fact use the heater plugs for as long as you can without burning them out.
 

Offline mtdoc

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #43 on: March 10, 2018, 07:48:53 am »
It is a question however how do the giant lithium batteries in electric cars perform after 5 years of use. Its pretty common for batteries in phones and laptops to really loose a lot of there capacity over a few years of constant cycling.

In the case of the Chevy Volt, it has a 8 yr, 100k mile warranty on its 16 kWh battery pack. There have now been many 6+ year old volts on the road with > 100k battery miles (some with >300k total miles) and at least as of a year ago or so, Chevy reported no battery replacements due to decreased capacity.  It’s worth noting that the Volt’s engineers chose to be extremely conservative in their setting of charge/discharge limits so that only the middle 80% or so of the battery capacity is used.
 

Offline nctnico

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #44 on: March 10, 2018, 08:56:23 am »
The snag with capacitors, super ones or not, is that they lose half the charge energy when being charged, Q=1/2CV^2. This is rather inefficient.
That doesn't make sense. You can't magically loose half the energy (laws of energy preservation). What you are probably referring to is that you can't use all of the energy stored in a capacitor because at the end of the discharge the voltage will be too low to do anything usefull.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline nctnico

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #45 on: March 10, 2018, 08:59:35 am »
It is a question however how do the giant lithium batteries in electric cars perform after 5 years of use. Its pretty common for batteries in phones and laptops to really loose a lot of there capacity over a few years of constant cycling.
Lithium batteries in cars are treated much better compared to phones and laptops which have a designed lifespan of 3 years. A good example is the Toyota Prius. As far as my information goes very few batteries failed in these cars. What they typically do is charge the batteries up to 80% to 90% and don't discharge them under 20%. That way you can get many more cycles out of a Li-ion battery. Bonus points if the battery pack is actively cooled or heated (which is missing on the Nissan Leaf BTW).
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 
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Offline james_s

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #46 on: March 10, 2018, 09:25:22 am »
When the Toyota Prius first came on the market I was certain that within a decade the junkyards would be filled with perfectly good hybrid cars that just had bad battery packs. In reality they have proven to be *far* more reliable than I ever imagined and replacement packs cost ~1/5th what they used to. My other half has a 2002 Prius still going strong on the original hybrid battery, I replaced the original 12V AGM battery a couple years ago when it failed. It remains to be seen how well the Li-ion batteries in pure electrics hold up but I know several people with early generation Nissan Leafs that are still doing fine.
 
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Offline SL4P

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #47 on: March 10, 2018, 07:32:24 pm »
(Energy + Heat) / Time = Fire
Don't ask a question if you aren't willing to listen to the answer.
 

Offline digsys

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #48 on: March 10, 2018, 07:36:55 pm »
Quote from: james_s
When the Toyota Prius first came on the market I was certain that within a decade the junkyards would be filled with perfectly good hybrid cars that just had bad battery packs. In reality they have proven to be *far* more reliable than I ever imagined and replacement packs cost ~1/5th what they used to. My other half has a 2002 Prius still going strong on the original hybrid battery, I replaced the original 12V AGM battery a couple years ago when it failed. It remains to be seen how well the Li-ion batteries in pure electrics hold up but I know several people with early generation Nissan Leafs that are still doing fine

The biggest surprise is - that swapped out battery packs from ALL EVs are in HUGE demand !! We have groups of people snapping up USA swapouts
by container load (not full of course). 20% down in a car may be undesirable, but they have a LOT of other uses, especially since you know that most
are from the same batch and pretty well matched. Any extra conditioning is a snap. Tesla swap-out packs are in hysterical demand, Tesla owners
often swap them out at 5% (or less) down. They need to always beat every car on the road it seems :-)  win-win
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Offline Psi

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Re: charging up your electric car in 10 minutes - supercapacitors
« Reply #49 on: March 10, 2018, 08:12:56 pm »
It's not cold here either, i only did it for fun :) and i was sick of replacing car batteries every 2 years.

Well a car battery should certainly last longer than 2 years, tho the Australian heat likely is not good for those batteries ether. But im pretty sure a supercap can extend the life of it by 3x easily. Perhaps the batteries even age slower if they are not repeatedly exposed to those large discharge currents.

I'm pretty sure it's just crap/cheaper materials used, and no desire by the local manufacturers to make them last longer.
It's very common here to buy a jap import car and have the jap brand battery last for 7 years. Only to replace it with a local battery that then lasts 2-3

Also i didn't add the caps in parallel, i replaced the battery with caps. <gasp>
sure, if i leave the lights on it's flat in 4min not 2 hours, but they should outlast the car.
« Last Edit: March 10, 2018, 08:15:45 pm by Psi »
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