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Ultrafast-charge and -discharge bulk battery electrode

Discussion in 'News' started by suxxer, May 10, 2011.

  1. suxxer

    suxxer ElektroVolt

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    The guys from the Paul Braun Research Group at the University of Illinois have published a very interesting article about fast charging. We could see fast-charging batteries by 2013!

    http://braungroup.beckman.illinois.edu/

    Published in Nature Nanotechnology:
    http://www.nature.com/nnano/journal/v6/n5/full/nnano.2011.38.html
     
  2. raymond

    raymond Member

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    90% of 56kWh in 2 minutes requires 1.5MW. The Roadster has the advantage that when charging there is at least the theoretical possibility of charging each cell individually. The still requires 219W/cell. At 3.75V this is almost 60A to each cell. 60A requires AWG 4 wire (5mm or 3/16" diameter).

    I can't see a charging system with 2x 6831 AWG 4 wires.

    On the other end of the spectrum you might want to run two single wires charging at 400V / 3750A. Having just talked to my friend at the railroads this isn't as impossible as I thought. Trains (in the Netherlands) actually run at up to 1500V / 4000A. I wouldn't like to plug in that 500mm2 cable (each wire being approx 5cm / 2" thick).

    Does anybody here have any ideas on how this is going to work out in real life? Assuming cell chemistry will improve this much, what's the charger going to look like?
     
  3. dwegmull

    dwegmull 2013 Model S 85

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    That was my first thought as well... Maybe this could be useful for city busses, that could have relatively small batteries that are recharged at each stop via an automated contact arm built into the ground...
    This could also allow sustained regenerative braking while going down a long mountain road. Maybe for use in a long haul hybrid truck.
    Come to think of it, the "simplest" use is for high power application like in a sports car where there are a lot of bursts of energy, in both directions. The fast charge / discharge would be limited to the "internal energy path" while external charging would be pushed to whatever practical limit (Level 3 is already quite bulky / expensive) without battery life reduction.
     
  4. zack

    zack Member

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    The solution is obvious. Charge batteries with batteries. Charging stations will have a large pack of their own that's always held ready to dump into a car. It can charge back up when not in use.
     
  5. Kipernicus

    Kipernicus Model S Res#P1440

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    Are we on the starship Enterprise?
     
  6. TEG

    TEG TMC Moderator

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    Or with capacitors. With stationary storage, size isn't as important. Capacitors tend to do very well in discharge rate, and cycle life which would both be important for something like that. (Particularly if it were a shared quick charger handling many different EVs in a popular location.)
    Then you could put quick chargers in places that don't have 50kW+ power lines. Hmm... Maybe just build a box that sucks amps from J1772 on one side, stores it up, then can dump it out quickly on CHAdeMO when someone pulls up for a quick charge. Downside - expensive, and you have to wait a long time for it to recharge itself before it is ready to do another quick charge ouput.
     
  7. rabar10

    rabar10 FFE until Model 3

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    As mentioned above, even if the batteries themselves will accept it, coming up with a charger and the rest of the infrastructure (plugs, wiring, etc.) to do ultra-fast charging is quite the challenge. This is one of the places where gasoline has spoiled us. Quick math:

    - Electrical energy equivalent of a gallon of gasoline: 33.4 kWh
    - Speed of a fast US gasoline pump: 10 gallons per minute

    So the power equivalent of pumping gas into an ICE car is 334kWh/min, or ~20 MW(!).
     
  8. Norbert

    Norbert TSLA will win

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    Maybe by the time this is ready, metallic nanotubes will be ready as well, with about 10x the conductivity of copper at 1/6 of the weight... :)
     
  9. stopcrazypp

    stopcrazypp Well-Known Member

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    #9 stopcrazypp, May 10, 2011
    Last edited: May 10, 2011
    Keep in mind the differing pump/plug to wheel efficiency though: the Leaf gets 99MPGe which would adjust that downward to 1/3 or 6.68MW for the equivalent mph charge speed.

    An average tank holds about 13 gallons, so that points to only a 1.3 minute fueling time, which probably isn't typical of most pumps. I think about 5 minutes is already more than reasonable, which would adjust that to 1.74MW. If you are willing to double the charge time or take half the charge, that will further halve the calculation. In the end, fast charge only needs to provide a reasonable charging time for road-trips. It doesn't need to match the fastest gas pumps.

    1.5MW is probably not completely out of possibility. The Proterra bus already uses a 0.5MW charger (built with battery banks).
     
  10. suxxer

    suxxer ElektroVolt

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    Let's assume a 10min stop at the charger.

    We need to charge 90% of 56kWh in 10 mins. That gives us the need of 302.4 kW.

    302.4 kW supplied at 400 Volts requires 756 Amps. Thats approx. the max output of the Roadster which is 700 (non sport) / 800 (sport) Amps ;)
     

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