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bwilson4web
User Rank
Gold
Could do with a designer guide or app notes
bwilson4web   6/11/2013 11:08:07 PM
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Are their app notes or designer guidelines to help us size the ultra capacitor for the cell size and capacity? 

For example, single cell NiMH, LiON chemistries, and lead-acid batteries are going to have practical charge and discharge limits, typically a multiplier of the cell C rating. Given the C limit, what sort of capacitance provides what sort of C range extensions?

I know this reads like a Gadge Freak proposal but having a guide lets the designer make a practical choices.

Bob Wilson

Koldban
User Rank
Iron
Re: This would require a really large cap
Koldban   6/11/2013 12:51:26 PM
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The capacitor(s) are smaller and lighter than most would think.  I agree with what Jermey is trying to say in his article.  My company www.koldban.com has been marketing our KAPower supercapacitors for engine starting for several years.  The key here is that no one current technology offers both power and energy.  Power being how much and energy being how long.  By using a supercapacitor (a.k.a. ultracapacitor) in combination with a battery, it will minimize a battery's exposure to any high power transients.  Thus, allowing the battery to do what it is good at and that is providing energy.  In addition, in applications with multiple batteries one or more of the batteries can be removed since they are no longer needed to supply power.  ie: engine starting.

Jim S
User Rank
Gold
Re: This would require a really large cap
Jim S   6/10/2013 4:01:25 PM
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Agreed

Ratsky
User Rank
Platinum
Re: This would require a really large cap
Ratsky   6/10/2013 3:47:57 PM
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Jim, I tend to agree with your statements, but there is so much more that is not disclosed by the author.  This is more of a puff piece than what I would expect in something published by engineers for engineers.  What is the basic technology?  What are the tradeoffs?  I remember the earliest ultracaps (just a few years ago) were very low voltage (a few volts WVDC at best) and had an absurdly high internal resistance.  What allows these units to be described as essentially lossless?  Without some hard information and checkable references, this could easily be pie in the sky!

Jim S
User Rank
Gold
This would require a really large cap
Jim S   6/10/2013 12:21:35 PM
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The article doesn't address the size of cap needed for this. Let's say we have 1000F. The delta V ov the cap is say 100V on top of the normal 380V rail. This contains enough energy to power a 50Kw motor for 100 sec. assuming everything 100% efficient. While this would fill gaps for accelleration/decelleration, How big and heavy is a 1000F cap rated at say 600V?

jhankwitz
User Rank
Platinum
Surge Currents
jhankwitz   6/10/2013 10:39:54 AM
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It will be interesting to see how they manage surge currents.  Unlike a battery where the voltage drops considerably when a near dead short occurs as a starter engages, ultra capacitors will instantly pump near infinite current. They'll need to have a very robust wiring and electrical contact switching system to handle this.

TJ McDermott
User Rank
Blogger
Re: Who uses them
TJ McDermott   6/9/2013 7:54:58 PM
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I'd like to know what vehicles they are used in as well.

tekochip
User Rank
Platinum
BOM Vs Performance
tekochip   6/9/2013 11:46:13 AM
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Anytime you have to start up a motor repeatedly a big cap is the way to go.  Most of the time the expense of the capacitor precludes you from including it in the design, but an electric car is the perfect application.  The Bill of Material cost just isn't as important as performance is.  At least, for now.
 
I have gotten to use super capacitors in an application where battery life was very important.


Greg M. Jung
User Rank
Platinum
Re: Ultracapacitors, batteries join forces for fuel eficiency
Greg M. Jung   6/8/2013 6:07:24 PM
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Good article which presents many good points.  In addition to the previous question on why we haven't seen these earlier (cost/economic reasons?) it would also be interesting to know the weight per capacity tradeoff (i.e. larger capacitors can carry a larger charge, but are also heavier and can slow vehicle performance).  How is the size of the capacitor optimized for each vehicle?

Gorski
User Rank
Platinum
Ultracapacitors, batteries join forces for fuel eficiency
Gorski   6/7/2013 9:17:53 PM
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I can follow the wonderful things ultracapacitors can do according to the article. The items listed sound logical and seem to be exiating technology. So why haven't we seen or heard about automakers doing these things? Are they married to battery makers? As far as gasoline prices going down when consumption does I don't think that will ever happen. If it does it will be in far, far distant future.

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