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Fifteen (15) second bus charge

Discussion in 'Charging Standards and Infrastructure' started by Ciaopec, Aug 1, 2016.

  1. Ciaopec

    Ciaopec Reservations at Restaurant at Universe end

    May 3, 2016
    Close to where SpaceXploration begins: 32952
  2. ecarfan

    ecarfan Well-Known Member

    Sep 21, 2013
    San Mateo, CA
    The photo at the top of the article shows a Mercedes FCEV bus, but the article is about a bus built by a company called "Tosa". Poor image choice.

    The article states: "The fully electric buses roll into bus stops as they usually would, but then a contact on top of the bus rises to meet an overhead charger. Thirteen of 50 stops have the charging technology. The flash charger delivers up to 600 kilowatts for 15 seconds. At the bus depot, the chargers fill up the bus in three to five minutes using 200 kilowatts."

    I am wondering how an EV battery can charge at a 600kW level, even if only for 15 seconds. I looked all over the website but could not find any technical details. Closed I got to an explanation was here
    But that isn't an explanation of how it works.
  3. thimel

    thimel Member

    Feb 27, 2015
    The article in the OP makes clear that the charging station uses supercapacitors to store the energy the bus needs. My GUESS is the bus also has supercapacitors. Only 2.5 kWh is needed to take a 600 kW charge for 15 seconds. It also has batteries to allow it to go the longer distance from the depot to the route.
    Supercapacitors can charge and discharge VERY rapidly, limited only by inductance and lead resistance. Microsecond discharge times are possible in a properly designed system.
    • Informative x 1
  4. RichardL

    RichardL Member

    Oct 6, 2013
    San Carlos, California
    As far as I understand it allows a slow charge of the supercapacitor, in order to not overburden the local infrastructure, then a quick 15 second burst to transfer the roughly 2.5 kWh to the bus (maybe 5 - 6 miles worth of range).
    It doesn't seem to mention how the bus is designed - I guess it means that another supercapacitor on the bus receives the energy, and then it discharges to the battery at a much slower rate - the opposite of what happens in the charging station. I don't know if this is possible (or I misunderstood) - if it is, the idea of a 'flash transfer' is a great idea (equivalent to transferring a full charge to an 85 in less than 10 minutes)

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