DIY Electric Car Forums banner

41 - 60 of 72 Posts

·
Registered
Joined
·
44 Posts

·
Administrator
Joined
·
6,088 Posts
Why would a company use lithium cells and claim that they were supercaps?

Horribly I do think that is more likely than the huge cost and weight reductions

But I can't think of any reason for them to do that
 

·
Registered
Joined
·
44 Posts
You must have missed where they are claiming:
1 million cycles at 100% DOD with negligible capacity fade
a 45 year calendar life
operation without degradation at 85 °C
can be charged in less than 30 seconds without affecting cycle life
no risk of thermal runaway

See:
http://www.kilowattlabs.com/energy-storage-advantage.html
http://arvio.com.au/supercapacitor-brochure

And at 9:40 in this video, Paul Wilson implies they are completely non-toxic by claiming they are compostable, containing only carbon and paper, wrapped in aluminium.
https://youtu.be/WFef1VJHUaU?t=414

Every one of those claims would be ludicrous if they admitted it was a lithium ion battery (possibly with a few supercaps added for show).

But as a "Capacitor Module" those claims begin to seem plausible.
 

·
Administrator
Joined
·
6,088 Posts
I saw all that
But I still don't see how a company could hope to make any money doing this

If they have a huge demand - then people will open them up and see that they have been lied to

I just don't see how a company could hope to make money by selling something that is plainly not what they said it was

With current demand and their pricing they could sell a lot - I think that they are undercutting the Tesla product - as batteries

So why claim it's something its not and open yourself up to all sorts of legal issues?
 

·
Registered
Joined
·
44 Posts
I saw all that
But I still don't see how a company could hope to make any money doing this

If they have a huge demand - then people will open them up and see that they have been lied to
No. When you open them up, you see what looks like unlabelled capacitors. You can't tell they are LTOs by looking at them. Nor can you easily tell they are LTOs by their voltage vs SoC curves, provided you stay within the 44 V to 54 V limits specified by the manufacturer, because LTOs happen to be fairly linear in that region, particularly at the 2C rate.

The main reasons I am fairly confident they are LTOs are:
1. I have read extensively about the current state of the art in supercapacitors, and we're nowhere-near this energy density, even in the lab, let alone mass production. And the chance that some lone genius could leapfrog everyone else by about 10 years is negligible.
2. LTO cells are commercially available that look exactly like the "capacitors" in the Kilowatt Labs unit and they have exactly* the required voltage, internal resistance, energy capacity, weight, dimensions, linear region of voltage vs charge curve, and (as we've seen most recently) flammable electrolyte. * Within 5%. [Edit: And low enough cost]

Now we're waiting for Arvio to release a 1C voltage versus charge curve that goes outside of the linear region for LTOs.

At this stage, I'm assuming good faith on their part.
 

·
Administrator
Joined
·
6,088 Posts
Hi Weber

But you can tell from the voltage charge curve for a supercap - the slope on that curve is equal to the capacitance

We have been told the capacitance -
if these are batteries then they will have an effective capacitance of about four times that

So isolating one "capacitor" and doing a voltage/current curve will show what is happenning

I would LOVE it to be the supercap breakthrough!
But I think it's much more likely to be as you say
 

·
Registered
Joined
·
44 Posts
But you can tell from the voltage charge curve for a supercap - the slope on that curve is equal to the capacitance

We have been told the capacitance -
if these are batteries then they will have an effective capacitance of about four times that
Sure. But then they could just say they got the capacitance wrong and they're actually better capacitors than they thought! :eek:

So isolating one "capacitor" and doing a voltage/current curve will show what is happenning
Yes. But it has to go outside of the region where LTOs are linear. That's what I challenged them to do 4 days ago, and that's what we're still waiting for.
 

·
Registered
Joined
·
1,664 Posts
Discussion Starter #49 (Edited)
Paul W at Arvio has now posted a video of what he claims is a "recharge test of a 3000F supercapacitor"...
https://youtu.be/m_hyyQ5-d0E
It shows one of their devices charging from 0v to 2.7 v in approx 30 secs drawing something between 15 and 10 amps (cannot see the meter )
Which would suggest he has charged approx 0.3 Wh into that device !
But that implies to me that it is not a 3000F cap is in use there ?
Its going to need a lot more than 15 amps to charge a 3000F cap in 30 secs!!
 

·
Administrator
Joined
·
6,088 Posts
A 3000 Farad capacitor charged to 2.7 volts will require 8100 Coulombs

Which is 8100 Amp seconds

So if it took 30 seconds then it would average 270 amps
 

·
Administrator
Joined
·
6,088 Posts
Just watched the video

He has an average of 5.5 amps for 15 minutes - 900 seconds - 4950 coulombs

Not the full 8100 coulombs - but the way he "averaged" it looked a bit suss
 

·
Registered
Joined
·
4,606 Posts
Paul W at Arvio has now posted a video of what he claims is a "recharge test of a 3000F supercapacitor"...
https://youtu.be/m_hyyQ5-d0E
It shows one of their devices charging from 0v to 2.7 v in approx 30 secs...
I didn't bother watching the whole thing or listening to any of it, but text near the beginning notes that the voltage jumps to 2.7 almost immediately. That's presumably what misled Karter2, and it is also inconsistent with a capacitor. I assume that he is charging through a control circuit which throttles the charge rate - the voltmeter is seeing 2.7 volts, but that can't be across a capacitor being charged.

Why is nothing from these people straightforward and credible? :confused:
 

·
Registered
Joined
·
4,606 Posts
Just watched the video

He has an average of 5.5 amps for 15 minutes - 900 seconds - 4950 coulombs

Not the full 8100 coulombs - but the way he "averaged" it looked a bit suss
Suspect?

I see your comment on the video; it should be interesting to see the response. :D
 

·
Registered
Joined
·
8 Posts
As others have said .. plus -
IF they had said a 20-50% increase over what is currently available, I'd still be sus ... without seeing a string of patents and news articles in TECH magazines / papers. nada. At 50%, I'd be seriously skeptical though. But what they claim .. well, put up or shut-up :) .. your serve
 

·
Registered
Joined
·
1,058 Posts
Old news is old but...

Duncan said:
So 8.5% at 44v and 95% at 53v

Just don't see how you do that with Supercaps unless you set the "zero" at 40v
So if 2.7v is full then "zero" would be 1.9 volts

Maybe that is how they do it - it's actually a 12 kWh pack and they are only using the top 3.5 kWhs
The energy stored in a capacitor is not linear with voltage as it (sort of) is with batteries.

Energy = Capacitance * Voltage * Voltage / 2

So at double the voltage you have 4x as much energy. At 4x the voltage you have 16x as much energy.

It does actually make sense that the voltage skyrockets immediately under very little current flow, and that by the time you drain it even to half voltage, most of the energy is long gone.

Vaporwear is vaporwear.
 

·
Administrator
Joined
·
6,088 Posts
Good point so if it was 1.9v to 2.7v

That would be 3.61 to 7.29

So the 3.55kWh pack would actually be a 7 kWh pack that they were only using 3.55 kWh
 
41 - 60 of 72 Posts
Top