Lithium Battery Plus Supercapacitor equals Double Fast Charging.

[Delusional]

In my experience...
The lithium ion battery is usually charged at high amperage from zero to eighty percent capacity and then the charger switches to a lower voltage profile and it takes about the same amount of time to get from 80 percent to 100 percent. It's fast to 80 percent, then much slower to top off. This is called the CC/CV Constant Current/Constant Voltage charge profile. There are several reasons why this is done, but it's mostly fire safety. I am 98 percent positive that Tesla uses something like this in their battery charging scheme.
Supercapacitors accept a full charge in a matter of seconds.

So now we're fully charged, let's go discharge.

I went over to battery university dot com looking for this specific piece of information.
"The supercapacitor (self)discharges from 100 to 50 percent in 30 to 40 days."
My reaction was "very interesting, i would have guessed 30 to 40 minutes."
Battery University Supercap Info

Let's say that on top of the previously existing Tesla battery, you add supercapacitors with about 30 percent of the lithium battery's total capacity. Now you can do the fast part of the lithium charging (up to 80 percent), and charge the supercapacitors in seconds. Now you drive away while the supercapacitors are used to top off your lithium cells.
You have just cut in half the time spent waiting for your Tesla to reach 100 percent charge.
Or, you can fully charge both assemblies, and hold thirty percent range in supercapacitor storage for a week or two.
Or, you can discharge the supercapacitors extremely quickly. You can bet that this will be done in the Roadster 2.0.
And that's the story of the jazz discharge party hat.

Very interesting indeed.

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[jebinc]

I would wonder how; reliability, longevity and safety of a super capacitor compares to that of a battery cell? I suspect it would be much worse on some or all dimensions, otherwise Tesla would already be using them, no?

 

[ajdelange]

It gets even more interesting if you look at some numbers. The tri-motor will have a range of about 500 mi and if it can do those at 350 Wh/mi the energy storage system will have to have a capacity around 175 kWh. If the top 20% of that were in super capacitors that would mean they would have to store 35 kWh which is 1.26E8 joules. Now we go to Amazon and see that with $290 we can buy a 16V supercapacitor with capacitance of 500F that weighs 10.36 lbs. One of these, fully charged, holds 6.4E4 joules so we would need 1.26E8/6.4E4 = 1969 of them weighing 20399 lbs and costing $571,010. Buying that many, though, you will doubtless get a substantial discount.

 

[Delusional]

Supercapacitors are far superior than lithium batteries in reliability, longevity, and safety. They will barely need a management system. The only thing they don't do better is hold the charge. It's all there in the BatteryUniversity article. I was extremely surprised when they said 30 days to 50 percent charge. I was guessing seconds. I'm used to working with electrostatic capacitors, and it appears super and ultra capacitors are entirely different beasts.

When Tesla announced the purchase of Maxwell someone immediately said that their ultra capacitors would be a great way to send a fast and strong boost of power to the motors in the Roadster 2.0, but I knew that wasn't the only possible use.
This is all logical and obvious. I would be very surprised if somebody somewhere has not pointed it out. I just have not been interested in a Tesla vehicle until they had a truck.

 

[ajdelange]

When Tesla announced the purchase of Maxwell someone immediately said that their ultra capacitors would be a great way to send a fast and strong boost of power to the motors in the Roadster 2.0, but I knew that wasn't the only possible use.
This is all logical and obvious. I would be very surprised if somebody somewhere has not pointed it out. ...

It's been pointed out many times. If you need 150 kW for 10 seconds that's only 1.5E6 joules and you could hold that in 25 of the modules I mentioned in the earlier post.. Another potential use is to absorb regen energy when the battery is too cool to accept it at the rate that the motors are producing it.

 

[jebinc]

It's been pointed out many times. If you need 150 kW for 10 seconds that's only 1.5E6 joules and you could hold that in 25 of the modules I mentioned in the earlier post.. Another potential use is to absorb regen energy when the battery is too cool to accept it at the rate that the motors are producing it.

So, then cost is the reason why knowledgeable Tesla engineers are not using them in their designs?

 

[Delusional]

OOPS
So a 50 kg array of ultracapacitors could potentially input or output 650 kW of burst power, though, at 0.18 kWh, this would last just a second or so..

 

[ajdelange]

Don't consider the capacitor module I mentioned as the gold standard for super capacitors. I just pulled that one off the net to serve as an example of where the technology that anyone can buy off the shelf today is and what its implications are with respect to the EV power pack. But do take away the message that super/ultra capacitors don't have the specific energy density required for the main powersource in an EV or even a substitute for a few percent of it but that they may be a great way to handle brief bursts.

I think the reason super capacitors haven't found their way into Tesla's yet (and they may have in ways I don't know about such as backing up power for a clock chip) is that the engineers just haven't figured out how to best use them yet. I don't think Elon bought Maxwell because he has a dog named Max.

And, of course, technology will continue to advance.

 

[hridge2020]

It gets even more interesting if you look at some numbers. The tri-motor will have a range of about 500 mi and if it can do those at 350 Wh/mi the energy storage system will have to have a capacity around 175 kWh. If the top 20% of that were in super capacitors that would mean they would have to store 35 kWh which is 1.26E8 joules. Now we go to Amazon and see that with $290 we can buy a 16V supercapacitor with capacitance of 500F that weighs 10.36 lbs. One of these, fully charged, holds 6.4E4 joules so we would need 1.26E8/6.4E4 = 1969 of them weighing 20399 lbs and costing $571,010. Buying that many, though, you will doubtless get a substantial discount.

 

[Keeney]

Check the units conversion, prices, and size/capacity of available supercapacitors. I think you will find that amassing the requisite number of kilo-watt-hours with current super-cap technology is still orders of magnitude too expensive, orders of magnitude too large, and orders of magnitude too heavy.

 

[T3slaDad]

Check the units conversion, prices, and size/capacity of available supercapacitors. I think you will find that amassing the requisite number of kilo-watt-hours with current super-cap technology is still orders of magnitude too expensive, orders of magnitude too large, and orders of magnitude too heavy.

I was just about to say the same thing. The problem with super and ultra caps isn't that they aren't superior in every way possible, but that they require 10-15x as much SPACE as batteries for the same storage capacity.

To put that into perspective, even if you tried to offset only 1% of the battery pack with caps, you would need to fill the entire frunk. No frunk for the benefits of 3-5 miles worth of super or ultra caps isn't worth it, let alone where in the world would you store 20-30 miles of capacity as caps? You can have a trunk or have supercaps, take your pick.

 

[Delusional]

Why did you have to revive this thread after 10 months?
It was better off dead.

 

[T3slaDad]

Why did you have to revive this thread after 10 months?
It was better off dead.

Oh man, sorry about that! I didn't see when the last post was, it popped up in my recommended feed.