TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker or making a Paypal contribution here: paypal.me/SupportTMC

Flash Charging a Model S?

Discussion in 'Model S: Battery & Charging' started by AMPd, May 31, 2013.

  1. zeron

    zeron Member

    Joined:
    Dec 30, 2012
    Messages:
    72
    Location:
    Milky Way
    That bus probably uses supercapacitors, not batteries like the Model S. They allow for that ridiculous charging power at 400kW.
     
  2. deonb

    deonb Active Member

    Joined:
    Mar 4, 2013
    Messages:
    3,020
    Location:
    Redmond, WA
    Interesting - it will recharge 1.6 kWh in 15 seconds. I would think the bus probably gets no better than 2 kWh per mile. So it gets just under a mile of charge at every bus stop - probably all it needs.

    Cool model!
     
  3. jeff_adams

    jeff_adams Member

    Joined:
    Mar 18, 2013
    Messages:
    617
    Location:
    Monterey
    On May 9th Elon announced "there is a way to recharge a model s faster than you could fill up a tank of gas." That sure sounds like some sort of flash charging. Javier repeated that statement later on.

    What I find interesting about the timing of that statement is a news story came out in the spring about a high school girl in Silicon Valley that won 2nd place in a Science competition. She used a supercapacitor to recharge a cell phone battery. Could the process that she discovered be duplicated in recharging an EV? Could Tesla have hired her since she already lives nearby?
     
  4. deonb

    deonb Active Member

    Joined:
    Mar 4, 2013
    Messages:
    3,020
    Location:
    Redmond, WA
    Because Elon forgot all of his Ph.D. studies in Super Capacitors and now need to hire a high-school kid to re-educate him? :)

    The last he talked on this subject was May 20th in regard to her prize.
    elonmusk: @yes_andre I'm a big fan of ultracapacitors. Was going to do my PhD at Stanford on them. But we need a breakthrough in energy density...
     
  5. jeff_adams

    jeff_adams Member

    Joined:
    Mar 18, 2013
    Messages:
    617
    Location:
    Monterey
    Maybe her breakthrough wasn't so much the capacitor, but how she used it to charge. Did she have to remove the battery from the phone first? Was she as able to charge it up through the existing plug? How would she have gotten so much energy through it without melting something?

    It's the transfer of a large amount of energy in a short time without over heating the battery that I wonder about. Pulse charging? Some other method?
     
  6. deonb

    deonb Active Member

    Joined:
    Mar 4, 2013
    Messages:
    3,020
    Location:
    Redmond, WA
    #7 deonb, Jun 2, 2013
    Last edited: Jun 2, 2013
    Eesha Khare's invention did not have anything to do with charging a phone battery. The 'fast charging a phone' scenario was just an idea that made her interested in researching the SuperCapacitor field in the first place. The mainstream media as always has no idea what it is she actually invented, so they focused on that one aspect and ran with it.

    Her actual invention (what she got the prize for) was about improving the energy density of a SuperCapacitor:
    http://www.usc.edu/CSSF//History/2013/Projects/S0912.pdf

    Basically she created a new nanostructure that allowed her to get storage capacity of around 238 F/g. Then she manufactured some, charged it up in 20 seconds, and used it to power a LED. So her project has nothing whatsoever to do with a phone.

    Her claim is that the 238 F/g that she achieved is up from a previous max of 80 F/g. However, the Kaner/El-Kady DVD-laser graphene supercapacitors gets 276 F/g. However, I'm not sure if it a fair comparison to compare graphene against nanorods. (Well, at least you can make graphene :)). Either way, 238 F/g is still awesome.

    However, to put things into perspective - the energy density for her SuperCapacitor is 20.1 Wh/kg. The Model S battery cells are 241 Wh/kg.

    So the SuperCapacitor would still weigh 12 times more than the current battery. That's why Elon said we're not quite there yet.
     
  7. dpeilow

    dpeilow Moderator

    Joined:
    May 23, 2008
    Messages:
    8,572
    Location:
    Winchester, UK
    I had a ride on this bus this week. Amazing bit of kit.

    It is doing a test loop between Geneva airport and the Palexpo exhibition centre where the motor show takes place, part of route 5. This takes in a short stretch of highway and is about 1 mile between the two stops. Consequently, as there was no big show on I had the bus to myself.

    It really does recharge in 15 seconds. When I returned to my start point I got out and crossed the street. By the time I reached the other side, the pantograph had lowered again and it was ready to leave.

    Not only that, but it performs like any other bus and has enough performance to accelerate onto the highway feeder road that takes it to the airport. I know the Geneva bus route 5 quite well and this section has to be the toughest for it to tackle.

    I tried to find out further information on the drive train. The charging station itself is using ultracapacitors to keep the grid demand at 50 kW, while supplying 400 kW to the bus when needed. There's little info on what is in the bus, but my guess is lithium titanate batteries as the storage is put at 40 kWh and they can give the bus a long charge at the depot.


    20131217_132553.jpg

    20131217_132311.jpg

    20131217_132321.jpg

    20131217_132711.jpg



    Not only that, but my old friend the Geneva Model S was stationed at the hotel where we were meeting again. I drove this one last time I was in town.

    20131217_090920.jpg



    And to top off a trip of fast EVs, I found myself riding down there on the world speed record holding train (yes, that's 360 mph) :)

    130920112628674154.jpg
     
  8. mknox

    mknox Well-Known Member

    Joined:
    Aug 7, 2012
    Messages:
    8,556
    Location:
    Toronto, ON
    I think that was in relation to the Battery Swap system that does recharge a "Model S" (as opposed to a Model S Battery) faster than filling up a gas tank.
     

Share This Page