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This discussion relates to Technology Review's article Battery Breakthrough?.

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  scotty1024
  

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  01/23/2007 04:07 PM

  All I want to know is

  How do you deliver 15KWH into an energy storage unit in a vehicle at home in 10 minutes?
  
  You need a peak energy capacity of 90KWH to achieve a 10 minute charge.
  
  Even if the owner installed a 3 phase hookup the device would, with 100% efficiency in conversion from AC to DC, consume 187.5 amps of current for 10 minutes.
  
  That seems a bit impractical to me even ignoring how one would achieve 100% efficiency.
  
  Perhaps they are going to sell you two ESU's? One in the vehicle and the other slowly charging up at a more practical charge rate and then use some 3500V DC transfer process to dump 15KWH into the vehicle in 10 minutes? Even that would involve handling a peak current of 26 amps at 3500V.

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  • 
    gh
    

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    01/23/2007 07:32 PM

    Re: All I want to know is

    I think the point of the "10 minutes" number was that an ultracapacitor doesn't intrinsically have a long charge time; if you can pump the power in at 187 amps, it can absorb it.
    
    However, if you assume a 1 hour charge time, it's under 32 amps; similar to an electric range.
    
    On another topic: sensitivity to low temperatures is a non-issue.  As a practical matter, people who live in climates where -40º C occurs - maybe 1 in a million car owners? - generally have garages and plug-in engine heaters, because lubricants are too viscous to work properly at those temperatures.  The vast majority of cars never experience even -25ºC.

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    • 
      lazz
      

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      01/24/2007 05:15 PM

      Re: All I want to know is

      I'm sorry, but that projection is not at all accurate. As an example, Calgary, AB, CA reached a temerature of -30.6 degrees Celcius on November 28th of this year. that's a city of just over one MILLION people, not to mention the surrounding cities of Banff, Lake Louise, and even Edmonton, another large city. And while many residents have garages, few are heated. All cars sold also come with block heaters up there, but that's only handy if you've got a plug, meaning anyone living in an apartment or townhouse or condo that doesn't have that available with their parking can't use it.
      
      There are many additional cities in Canada and the  northern US that see temps in the -20 to -30 range. not to mention European and eurasian cities. They drive too, you know.
      
      So I've got to point out that many cars do indeed regularly see lower temps than -25C. It helps to think globally instead of nationally when dealing with a potential technology that would (if it works) absolutely havea  global impact.

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  • 
    karn
    

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    01/23/2007 08:58 PM

    EV charging power classes

    There are three more-or-less "standard" power classes of EV chargers.
    
    Class 1 uses what you can pull from an ordinary 120V convenience outlet, about 1800W @ 15A. The portable "convenience charger" carried in the Gen 1 EV1's trunk was a class 1 charger. Most home "conversion" EVs also use Class 1 chargers.
    
    Class 2 is about 6 kW, roughly what an electric clothes dryer takes, and requires hard-wiring to a 240V supply. The EV1, Honda EV+ and several other EVs all used Class 2 chargers consuming about 30A @ 240V.
    
    Class 3 is about 50 kW. GM built a prototype class 3 inductive charger for the EV1, but they never put it into production. Obviously such a load is difficult to handle in a residence, so it would normally be a public recharging station fed with 3-phase 480V.
    
    The Tesla proposes a fast charger that draws 70A @ 240V (16.8kW). This is still within the capability of most homes, especially at night when other large loads are off. Based on my 5 years of experience driving the EV1, this increase in charging speed over the 6kW EV1 charger would be very nice to have.
    
    

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  • 
    GaryB
    

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    01/24/2007 04:26 PM

    Re: All I want to know is

    I'm a machine learning dude, quite useless here.
    Could one of you EE majors discuss the potential and problems of inductive charging? 
    
    Couldn't you make roadways with sections of underground inductive charging where you get an electrical boost from driving over it while your monetary charge account gets a dent?  Sort of like gas stations on the go.  Using this, maybe your battery/hyper-capacitor wouldn't need to have such a large range. 
    
    How fast could you pragmatically transfer energy this way?

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  • 
    Neilzero
    

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    10/10/2007 01:15 AM

    Re: All I want to know is

    I hope scotty will forgive me for copy, paste and edit of his post. scotty1024  01/23/2007 4:07 PM
     
    How do you deliver 15KWH into an energy storage unit in a vehicle at home in 10 minutes?
    Me: Your utilty has several thousand volts, single phase, on a pole about one  hundred feet from your house. They will run this into your house for about $1000, and they will charge you a higher rate if you use 90 kw a few minutes per day. This is called use of demand. They will also charge you extra because your charger will distort their sine wave significantly. If you want even faster charging they will likely charge you more than $1000 for the hookup. If you use a second ultra capacitor to limit the charge rate they may give you a reduced rate as you will be doing power factor correction, and less sine wave distortion. With good luck you won't need a transformer. You may also get a reduced rate if you charge slower after midnight.
    scotty: You need a peak energy capacity of 90KW to achieve a 10 minute charge.
    
    scotty: Even if the owner installed a 3 phase hookup, the device would, with 100% efficiency in conversion from AC to DC, consume 187.5 amps of current for 10 minutes.
    Me: That is high for average, I think. Perhaps somewhat more when you first start charging the discharged ultra capacitor, unless you add a costly constant current device. The electric utility will likely charge you $10,000 for a three phase hook up in a typical residential neigborhood.
    
    scotty: That seems a bit impractical to me even ignoring how one would achieve 100% efficiency.
    Me: 98% efficiency is possible if you can avoid using a transformer. If the power company voltage is a bit low, you can cool the ultra capacitor perhaps as cold as minus 20 f until the charge is complete. The capacitor voltage will rise as the ultra capacitor warms, assuming the ultra capacitor has a negative temperature coefficient of capacitance.
    
    scotty: Perhaps they are going to sell you two ESU's? One in the vehicle and the other slowly charging up at a more practical charge rate and then use some 3500V DC transfer process to dump 15KWH into the vehicle in 10 minutes? Even that would involve handling a peak current of 26 amps times 6 = 156 amps at 3500V.
    Me: 26 amps is average for a 60 minute transfer time. Perhaps 200 amps the first minute of 6 minutes, unless you add a costly constant current device.
    Things get really difficult if you want to put 100 KWH in your big SUV in ten minutes. The Tesla roadster uses a 53 KWH battery for a 200 mile range, so EE must be thinking a tiny car.  Your extra ESU can power your house if the utility is blacked out, but you need 3 or 4 special design inverters with inputs in series for 3500 volts.
    I'm wondering how EE will switch 3500 volts to provide a near constant output voltage to the load as the ESU nears discharged? 3500 volt solid state relays are costly even at low current.   Neil  

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  Draq Wraith
  

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  01/23/2007 08:02 PM

  Hum doesn't sound very green

  Hi all, one question for you.
  Isn't barium a radioactive isotope?
  Seems to be if and when this device fails your are going to have major waste disposal problems down the road.
  If it is discharged with a wire across both terminals it should heat up and radiate, or at a  full maximum charge it should heat up and radiate due to extra electrons bouncing around.
  Not sure which way it goes.
  Can someone test it for me with a dosimeter?
  
  Thanks
  Sincerely;
  Draq Wraith

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  • 
    henrys
    

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    01/23/2007 10:00 PM

    Re: Hum doesn't sound very green

    Radioactive isotopes are not a problem in any way. ENRITCHED radioactive isotopes are, as well as artificial radioactive isotopes.
    Why would there be a problem with disposing of an element taken from nature? If you take material X from a mine, use it and then dispose it in an environment similar to the one you took it from, it wouldn't produce any damage to the environment.
    If you take a material that has an extremely low concentration of a cetain isotope and concentrate it thousands of times, that's a more difficult waste to dispose of, but still feasible without impact. The real problem comes from artificial isotopes. If you take an isotope with a half life of a billion years and transform it into an isotope with a half life of a thousand years, significantly more radioactive, THAT's a thing that's difficult to dispose of.

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  • 
    zwol
    

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    01/23/2007 11:04 PM

    Re: Hum doesn't sound very green

    No, barium has lots of stable isotopes.  In fact, (according to Wikipedia) all of its radioactive isotopes are synthetic.  Natural barium isn't radioactive at all.
    
    Possibly you are thinking of radium, which is one row under barium on the periodic table, and is indeed extremely radioactive?

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    • 
      Draq Wraith
      

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      01/24/2007 03:16 AM

      Re: Hum doesn't sound very green

      Dear zwol; No, I am thinking of Hospitals use of barium enema's for radiology to get a picture of the rectum. I guess it could be made to preform for just that purpose.
      
      And It also states all "All water or acid soluble barium compounds are extremely poisonous"
      
      That is the part that gets me thinking this is not a very green (By green I mean cradle to cradle recycling) technology. Everyone who has had a radio or player of some kind has had a capacitor fail or a resistor fail. These devices will fail at some point in the life cycle and when they do it will more than likely be thrown away in a landfill. This technology is a good start but lets hope they find a more earth friendly way to do it.
      
      D~W

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      • 
        matt_kizerian
        

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        01/24/2007 04:19 AM

        Re: Hum doesn't sound very green

        The barium compound (a suspension of barium sulfate) used in radiography isn't radioactive. Quite the opposite, it is opaque to X-rays (gamma rays) and is used to add contrast to radiographs of the intestines and urinary tract, enabling the radiologist to better see tissues that would otherwise lack detail.
        
        Even though barium is toxic, barium sulfate can be used safely because it is so insoluble in gastric juices and is completely eliminated by the digestive tract.

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        • 
          elecdrivr
          

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          01/29/2007 12:19 PM

          Re: Hum doesn't sound very green

          Sodium and Chlorine are extremely dangerous and poisonous, yet common salt, NaCl, in small amounts is an essential mineral in our diet

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      • 
        kale
        

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        01/24/2007 04:22 AM

        Re: Hum doesn't sound very green

        environmentally friendly?
        compared to what? Lead-acid batteries lasting a mere 500-700 cycles?
        ICEs producing countless dangerous substances during it's hot and inefficient short lifetime?
        
        for everybody's sake i hope EEStor delivers and be the enabler to go electric and change our mobility for ever.

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  • 
    run
    

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    01/26/2007 10:47 PM

    Re: Hum doesn't sound very green

    Green would refer to it's collateral impact not it's owner/users/customers/etc. aspect.
    
    Toxic is not the antonym especially if it rendered people extinct.  The polar bears etc. would have less of a challenge surviving global warming for that then if we manage to hang around.
    
    AM I wrong about this?  I thought 'green' referred to the earth and future days beyond our mortality or even that of our species.  It's the external aspects of gadget or conduct that matter most.  Bring poisons and hazards closer to people is not relevent to assessing greeness.......

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    • 
      Elroch
      

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      03/22/2007 06:27 AM

      Re: Hum doesn't sound very green

      Just in case anyone is confused by the original (very poorly informed) comment in this thread, barium (like every other element up to lead, except technetium) exists as stable isotopes under natural conditions. Like every other element (including carbon, hydrogen and oxygen), it has radioactive isotopes which only occur naturally at very low levels.
      
      And the barium used in hospitals is, indeed, non-radioactive.

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