Super Capacitors

Discussion in 'OnBoard Electronics & Controls' started by Doug Lord, Jan 13, 2009.

  1. marshmat
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    marshmat Senior Member

    There are of course plenty of other factors involved, robherc, but yes, you've hit on the big problem that we would encounter if we start deploying electric cars on a wide scale. Significant improvements to the generation and transmission grid would be necessary, otherwise we'd end up with widespread blackouts.

    Canada had that blackout too, it spread all through Ontario, New England and most of the Great Lakes states in minutes. Really woke us up to just how fragile the power transmission grid is.
     
  2. Doug Lord

    Doug Lord Guest

    Is it possible that as part of this development some thought has been given to extremely high capacity charging systems/generators -maybe using fuel cells or some other advanced technology? The idea would be to separate this technology from the grid?
     
  3. Boston

    Boston Previous Member

    we used to leave a live cap on the work bench just to give the folks who couldn't keep there hands off stuff a lesson
    shoulda rigged a camera to go off
     
  4. robherc
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    robherc Designer/Hobbyist

    Boston:
    Hmmm...if you're gonna use a 3.5KV, 52.2KWH cap, you might want to put a disclaimer on your electrocution bench...but the smoking body would prob. keep others away!...rofl

    Doug:
    The problem with fuel cells is that they ARE, in effect, batteries. We don't simply harvest Hydrogen from the atmosphere/mines/whatever in any significant quantities...the only way to come by enough hydrogen to power the automotive industry is to MAKE it through electrolysis breakdown of water, so you still have to generate the electricity to make the hydrogen some other way. Long description above to say: Hydrogen fuel cells may be a great way to TRANSPORT energy, but the grid still needs to be upgraded so it can generate/handle the amounts of energy required by these electric vehicles. To say "the world isn't ready," in this case, is all-too-practical an answer!
     
  5. Boston

    Boston Previous Member

    no we didn't use a very big one, but after who knows how many people being told not to touch anything ended up standing over some broken something on the floor looking stupid, we decided a nice inviting juicy blue thing placed right in the front of all the other stuff might be in order.
    worked every time.
    hey we told ya not to touch anything
    course that was way back in school and we were kinda apt to play a few "harmless" practical jokes from time to time
    B
     
  6. ancient kayaker
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    ancient kayaker aka Terry Haines

    We used to leave a Tantalum capacitor connected backwards to a DC source if we wanted to teach terminally curious folk a lesson. They exploded with a mighty bang with tiny bits of confetti drifting down from the ceiling and the most awful stink that you could actually taste. Didn't hurt, but it nailed all the other 4 senses!

    I accidentally subjected myself to this trick as a young graduate when I hooked up a bank of big ones to a 60V 50A DC supply and turned it on. I was deaf for most of the day!
     
    Last edited: Jan 19, 2009
  7. marshmat
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    marshmat Senior Member

    Clever ideas Boston & AK..... might have to try that in our lab if people start stealing stuff again....
     
  8. Willallison
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    Willallison Senior Member


    Sorry to leap way back to page 1... but I couldn't help but take exception to what can only be a typo from IV.....;)

    Bloody good thread BTW...
     
  9. Boston

    Boston Previous Member

    something inviting about a big blue thing "obviously" not attached to anything that screams pick me up play with me louder than a prom date
    let us know how it works out
    B
     
  10. sailor2
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    sailor2 Senior Member

    How about recalculating that claim.
    3.25 Wh/kg = 65Wh/20kg, a far cry from 600Wh/kg a standard battery is capable of.
    In other words you need more like 200 kg of those to match 12 kg of battery.

    Same problem with post #3
     
  11. Fanie
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    Fanie Fanie

    Mind the big caps, they can be dangerous. I've heard of incidents where large electrolytics exploded with unfortunate results.

    I once supplied a customer with a batch of units where there are 3300uF 25V caps in... one cap was the wrong way round in one PCB. I tried to find out what happened when it was switched on, but nobody that was there wants to talk. They probably all needed a change of clothes :D

    Mind the eyes folks. Even the glass ones are bloody expensive I've heard.
     
  12. CDK
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    CDK retired engineer

    Sailor2 I apologize for that stupid mistake. I sometimes try to do several things at the same time with this kind of results.
    The Maxwell datasheet really states 3,25 Wh/kg and under applications "portable power tools". What kind of tools?
     
  13. Boston

    Boston Previous Member

    your absolutely right Fanie
    although I have never seen one explode Ive sure seen one zap someone and its no joke
    well
    it is if your not the fool jumping round hollering
    we just used little battery sized ones that were easy to get a finger across
    put it right in front of the sign on the bench that says "do not touch"
     
  14. marshmat
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    marshmat Senior Member

    Sailor2,

    If you have a battery that gives you 600 Wh/kg I would love to hear about it.

    A good flat plate lead-acid battery can hold about 35 Wh/kg; some of the fancy spiral-cell ones are closing in on 50. The very best Li-poly cells I've worked with (a Saehan/Enertech product) were in the ballpark of 150 Wh/kg or more; trying to push Li-poly to 200 is not impossible, but very difficult and expensive.
     

  15. sailor2
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    sailor2 Senior Member

    I don't of course. At least that typo was already hinted at on the same post in the following line.
    So yes, it did back fire at me, but the initial typo still lead many to draw wrong conclusions about the capasitors potentials and therefore needed to be corrected. Batteries are still much better on stored energy/weight ratio, currently by at least 10 times, than best capasitors which was the point. And I don't see that changing anytime in near future, if even in distant one.
     
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