[ausev] Ultracaps

[Mike Seningen]

I think when I was looking at UltraCaps last summer they only had 2V 
UltraCaps ... so to get 200V
you needed 100 in series, but then that would drop your CAP by a factor 
of 100!

You also have to worry about the resistance of 100 in series.

Having a 15V UltraCap with the same capacitance is also a huge win.

My project was to convert a sports car to ICE comparable performance at
a reasonable budget -- sort of having all 3 points of a triangle ---- so 
I had
my work cut out for me :-)

I was thinking about having a hybrid pack that had some sort dual pack 
-- one for long term
energy and the other for short bursts for acceleration.  AGMs and 
UltraCaps were
considered for the short bursts, and LiFePO4 for high density, longer 
range storage.

I didn't get very far.....

Mike

Gil Dawson wrote:
> On Dec 31, 2008, at 10:09 A, Jim Watson wrote:
>   
>> I don't know very much about Caps,.. But I do know that they don't  
>> take very long to store a charge,...
>> Jim
>>     
>
> Turning it around, you might have put it, "They charge very quickly."
>
> On Dec 31, 2008, at 8:46 A, Brian Lasseter wrote:
>   
>> I prefer some of the Ultra-caps from Maxwell
>> Technologies.  You can get nice 15V, 50F caps for $200.  (In a form
>> factor about the size of two fists.)
>>     
>
> 15V is new, I think.  The highest max voltage I had noticed before  
> was 2.
>
> The energy stored in a capacitor rises with the square of the  
> voltage, so this is huge.  A 15V capacitor can store (225/4=) over  
> FIFTY-SIX TIMES as much energy as a 4V capacitor of the same  
> faradiddity.
>
> To compare some very rough theoretical maxima...
>
> A 12V battery rated at 200Ah can store at most    12 * 200 = 2,400  
> watt-hours
>
> A 2V 50F capacitor can store    (0.5) * (50) * ( (2) ^ 2 ) =   100  
> watt-hours
>
> A 15V 50 F capacitor can store (0.5) * (50) * ( (15) ^ 2 ) = 5,625  
> watt-hours
>
> Now, that's getting somewhere.  (Somebody please check my figures.)
>
> On Dec 31, 2008, at 12:17 P, Jim Watson wrote:
>   
>> I just looked at the data sheet on a 500.0 F, 16.2 V cap. It says  
>> that it was designed for car applications. Also this cap that I  
>> looked at was around 5.75 kilograms = 12.67 lbs.
>>
>> E = (.5)(500)(16.2)^2
>> I think that is:   E=64,000 WH   ??
>>     
>
> I concur (I get 65,610 wh.)  That's 10 times the Farads and a squeak  
> more voltage than Jim's example above, so it checks.  I'm telling  
> you, this is new.  I looked all over the web (OK, it was a year ago)  
> and 2V was the max I saw.
>
> On Dec 31, 2008, at 12:17 P, Jim Watson wrote:
>   
>> What would charging this baby look like?? Would you just plug it  
>> into the wall for less than a fraction of a second, and be ready to  
>> go?
>>     
>
> Not quite.  They probably have a max amp rate through the connectors,  
> and you'd be limited by your power supply rating.  But there's none  
> of that chemical coddling that batteries require.  They'll probably  
> let you flow full current from zip to max.  Recharging an UltraCap  
> can't be anywheres near so slow as charging batteries.
>
> Contemplate these numbers for a minute.  More energy than can be  
> stored in ten car batteries, in a device that weighs less than 13  
> pounds and takes but a few minutes to charge.  What could you do with  
> that?
>
> From: http://www.priusownersgroup.com/?p=2989
>   
>> [A]n ultracapacitor-equipped Toyota Supra HV-R coupe became the  
>> first hybrid to win the 24-hour endurance car race held at Japan’s  
>> Tokachi International Speedway. The hybrid Supra finished 616 laps  
>> of the 5.1-kilometer (roughly threemile) course—19 more laps than  
>> the second-place nonhybrid Nissan Fairlady Z. “The Toyota that won  
>> was able to deliver energy more quickly, accelerate faster, and use  
>> braking generation more efficiently,” says Kevin Mak, an analyst  
>> with research and consulting firm Strategy Analytics and author of  
>> a recent study that explores the potential for ultracapacitors to  
>> complement and possibly even replace batteries in hybrid vehicles.  
>> “The days of the large hybrid vehicle battery pack may be  
>> numbered,” he adds.
>>     
>
>
> On Dec 31, 2008, at 12:17 P, Jim Watson wrote:
>   
>> "all of these products will perform reliably for more than one  
>> million discharge-recharge cycles." What does that bit about one  
>> million discharge recharge cycles mean?? Does it mean that one full  
>> trip in you car completing 1 full charge of the caps is = to 1 out  
>> of the million charges possible.
>>     
>
> That is how I read it.  Compare to a battery... you get, what?   
> Hundreds, thousands at most?  Ultracaps are qualitatively different  
> on this point.
>
>   
>> Damn that sounds great!!!
>>     
>
> Yes, doesn't it?
>
> So, what's their downside?  Anybody know?
>
>
>
> --Gil
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>   
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