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120KW vs 90KW & flatter curve

Discussion in 'Model S: Battery & Charging' started by napabill, Jun 28, 2013.

  1. napabill

    napabill Active Member

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    Regarding the recently announced Supercharger changes I have a couple of questions that don't appear to be answered in any existing thread I could find. Specifically,
    1. What does upgrading the SC from 90KW to 120KW really mean? A 33% increase in speed of charge? Anyway of knowing which SC's have that increased KW? Is this a rolling upgrade, and if so, what is the schedule. I assume the new SC locations this month will all be at the 120KW?
    2. The so-called flattening of the curve to allow higher rates of charge as one approaches 100%. Where is this accomplished? In the firmware of the car? Or in the SC. If in the firmware, has that already been incorporated, and if not, when? If in the SC, has that change occurred? If not, when?

    Pardon me if this information has been covered. But as usual I find nothing specific in TM's communications.
     
  2. apacheguy

    apacheguy Sig 255, VIN 320

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    Both features will require a software update. The software is supposedly in the beta stage now.

    TM is also upgrading existing chargers to Gen 2 with 120 kw support. I believe the Harris Ranch SC has been upgraded as well as Hawthorne and potentially more of them. The new stations going in now are obviously all Gen 2.
     
  3. JRod0802

    JRod0802 Member

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    Just in case you haven't seen it, cinergi posted a graph of what the charging looks like back in January:

    Then, after Elon announced the supercharger upgrade, this is what he had to say about it:

     
  4. napabill

    napabill Active Member

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    I sent this post in an email to TM Ownership. Here is their reply:

    "Thank you for reaching out to Tesla Motors and thank you for your inquiry. I will do my best to answer your question to the extent that we are allowed too at this time, so I apologize if some of the answer I give are vague.

    1) Currently our Super Chargers have an output lower than its full potential. When our Engineering team in charge of Super Chargers are ready to increase the output it should increase power output to an ideal potential of additional 30% (speculation and not fact at this time). This upgrade will likely come inform of firmware and hardware (not on the Model S but on the Super Charger units) but details will likely not become public, but if it does it will be available on our web site or made public by Elon Musk.

    2) The newest Super Charger is in Normal, IL is still at the reduce output or the old Super Charger set up, but can be retrofitted for higher output.

    3) We do not have an exact date when all units will have the higher output rate. Currently on the Super Charger website were show casing mainly the expansion plan of future Super Chargers as well as a potential future method of swapping out battery packs on road trips (not currently available).

    4) The flattening curve when Super Charger is a combination of technology from the vehicle and the Super Charger. I was told by Engineering that we would need clearance to release any more sensitive information other than what can be found on our website. Understand we will unlikely be given clearance to release more detail information, and when we do release more information it will be available on our website."
     
  5. drees

    drees Active Member

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    That's a nice chart right there, and it does look a little bit conservative compared to other fast charging of lithium batteries.

    A typical lithium charger will charge the pack at either max power or max current (which ever is the limiting factor) until a cell reaches max voltage. At that point the charge current will taper off as needed to keep the highest voltage cells from exceeding the max voltage. See Charging Lithium-Ion Batteries Battery University for example.

    So if you look at the chart, it's pretty clear that they start tapering off current well before the pack hits it's max voltage of slightly over 400V, so there's quite a bit of time there that could be spent charging at a higher rate.

    Now if you want to be more aggressive you can pump in even more current so that the pack voltage rises higher than the resting voltage at a full charge - this results in additional heat being generated in the cells and you have to even more carefully monitor temperatures and cell voltages to avoid accidental overcharging.

    I wonder how much current the connector and plug are rated for...
     
  6. goneskiian

    goneskiian Active Member

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    This also jives with some comments made by JB Straubel to a member of the officicial forums over at Teslamotors.com. SamoSam posted that JB had told him that the SC's were capable of higher than 120KW output.

    My Conversation with JB Straubel at Hawthorne Battery Swap | Forums | Tesla Motors

    Cheers!
     
  7. Robbo

    Robbo Member

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    Last weekend I met a member of the SC engineering team. He told me that Elan wants all of the SCs to be running at 120 by the end of August.
     

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