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No Supercharging for 40Kwh :(

Discussion in 'Model S: Battery & Charging' started by fairlycool, Dec 20, 2011.

  1. fairlycool

    fairlycool Member

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    Tesla won't be supporting supercharging for the base model which leaves me pretty disappointed. The only reason why they won't do it of course is to drive you to buy the 60 or 85 Kwh models which is pretty sad since I can't justify spending 10K extra just for that option though it would be nice to have.

    So sad :(
     
  2. Citizen-T

    Citizen-T Active Member

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    I'm pretty sure there are technical reasons.
     
  3. Zextraterrestrial

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    so that supercharge stations need not be so close together?
     
  4. Todd Burch

    Todd Burch Electron Pilot

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    Almost certain it's due to the limited C rate as a result of being a lower capacity battery pack (and possibly, to a much smaller extent, older Li-Ion chemistry).
     
  5. stopcrazypp

    stopcrazypp Well-Known Member

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    #5 stopcrazypp, Dec 20, 2011
    Last edited: Dec 20, 2011
    I kind of predicted this in older discussions (and also how the different packs might have different performance specs). The pure technical issue for this is that at the same power input (90kW), the 40kWh pack will have to charge at 2.25C vs 1.5 and 1.06 for the 60kWh and 85kWh packs respectively. 2.25C is going to degrade the pack significantly faster, while even the 1.5C is kind of iffy for frequent use (1.06C is okay; Panasonic cells are cycle tested at a 0.5C-1.0C). That's probably why Tesla is offering an unlimited mile warranty on the 85kWh pack (and probably won't even need to condition it against supercharger usage).

    I don't see why they can't offer the supercharger running at half power though, for the 40kWh pack. Although maybe they are considering that a 40kWh pack running at half power is going to take up the space for longer (on a per mile basis). And I'm no sure what the "optional" part for the supercharger on 60kWh pack means. Doesn't the same connector already support the supercharger? Maybe there are extra electronics needed (they didn't list a price)?
     
  6. AnOutsider

    AnOutsider S532 # XS27

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    There was mention of software: "Includes all software and on-board hardware"
     
  7. Norbert

    Norbert TSLA will win

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    Another reason may be that it is more difficult to install Superchargers at shorter distances along the highways.

    EDIT: Zextraterrestrial actually already mentioned that above...
     
  8. EVNow

    EVNow Active Member

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    Well, if a 24kWh Leaf battery with no cooling can be quick charged, I don't see why a 40kWh liquid cooled pack can't be. Besides, as you say, they can always use lower current.
     
  9. Todd Burch

    Todd Burch Electron Pilot

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    #9 Todd Burch, Dec 20, 2011
    Last edited: Dec 20, 2011
    90 kW in a 24kWh battery? YIKES. That battery might last 10 cycles :).

    If you want to use a lower current, why not use a 240v 50A socket?

    I don't think we know for sure that you won't be allowed to use the Tesla Superchargers. I think all we know for now is that you won't be able to charge at 90kW with the base pack.

    EDIT: After reading it again, I see that it's under a heading of "Super Charger Access" with "Includes all software and on-board hardware"....so it would seem that perhaps the base pack is mechanically or electronically prevented from having access to the Supercharger...so I think you're right about that.
     
  10. EVNow

    EVNow Active Member

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    #10 EVNow, Dec 20, 2011
    Last edited: Dec 20, 2011
    Just to re-iterate, the battery capacity shouldn't affect quick charging.

    A 85 kWh battery can be quick charged to 80% in 30 minutes by applying approximately 136 kW of power. That is 1.6C.

    A 40 kWh battery can be quick charged to 80% in 30 minutes by applying approximately 64 kW of power. That is 1.6C.

    So, even though you don't get the same # of miles out of a quick charge in a 40kWh battery compared to a 85 kWh battery, technically there should be no problem in quick charging the lower capacity battery at the same C rate as the larger pack.

    To use Nissan Leaf example, the 24kWh pack is quick charged to 80% in something like 24 minutes @ 2C. Nissan says the battery can be charged much faster - infact they recently talked about a 10 minute charger (which was badly mangled by most of the press).
     
  11. Todd Burch

    Todd Burch Electron Pilot

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    To paraphrase a former US president:

    That all depends on what your definition of Quick charge is...

    EVNow, what are you referring to when you say "Quick Charge"?

    Battery capacity absolutely affects quick charging, if you are referring to Tesla's supercharger (90 kW)...end users don't care about C rates...what matters for the end user with Quick Charging is miles/hour of charging. Since higher capacities give higher miles/hour of charge, there's an effect.

    I agree, there shouldn't be any problem quick charging the lower capacity battery at the same C rate as the larger pack.

    I'd say the lack of supercharger support for the base Model S is for at least 3 reasons:

    1) Tesla wants a way to pay for a nationwide network of Superchargers...forcing the upgrade to a 60 or 85 kWh pack is one way to help subsidize it.

    2) With the base pack, the superchargers would need to be MUCH closer together (perhaps 75-100 miles instead of 200 or so) for base customers to take advantage of them for long distance travel. That might require (VERY rough ballpark estimate) on the order of four times as many supercharger installations.

    3) Base pack customers are likely to be getting the car for short-distance commutes, and therefore a NEMA 14-50 is plenty for overnight charging.

    I'm sure there are more reasons.

    Edit: EVNow, I completely agree with you on a technical front (same C rate shouldn't matter)...I'm coming from an end user perspective, where the customer associates quick charging with miles per hour of charge.
     
  12. GSP

    GSP Member

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    I don't know, "Joe six-pack" might just as well recognize "80% charge in 30 min" as the definition of "fast charging." No reason to expect the smaller packs to have the same number of miles.

    I think that Japan's experience with ChadeMo has been that customers get much more use of low milage EVs, making them much more suitable to replace a gas car.

    It is a shame that Tesla will not offer fast charging on their 160-mile car. Best to get a TwinCharger and hope for some 80 amp ESVEs to pop up. Hope is not a good plan however. I know that wasn't how Japan got ChadeMo stations.

    GSP

    PS. The Leaf, the "i" and probably GM's Spark EV all support DC fast charging. Tesla is not keeping up in this department.
     
  13. Todd Burch

    Todd Burch Electron Pilot

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    I'm still not seeing where you guys are saying the 40 kWh pack doesn't support quick charging...maybe I'm missing it?

    All I'm seeing is that the 40 kWh pack doesn't support the Tesla Supercharger (and I think this is for business reasons, not technical reasons).

    But is there anything that indicates it can't do other types of DC quick charges?
     
  14. qwk

    qwk Model S P2681

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    Nope, they are just ASSuming....
     
  15. Norbert

    Norbert TSLA will win

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    I see your point, however Tesla also doesn't offer an 80 mile range or 100 mile range option. If you consider all the points made above (and in related threads), I think it comes down to Tesla's philosophy of offering good solutions first at the necessary higher price point and then drive the price down, meaning for Bluestar, or perhaps earlier, the price for an about 60-85 kWh pack including supercharging will be significantly lower. Tesla first focuses on offering a good solution and then lowering the price, whereas others focus on starting with a low price and try to squeeze in features.
     
  16. stopcrazypp

    stopcrazypp Well-Known Member

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    Completely different chemistry. The standard Lithium cobalt laptop cells in the 40kWh Model S are probably the worst in terms of charging/discharging C-rates and cycle life out of the battery types being used in EVs. Tesla just addresses that problem by using lots of them. Standard cycle life tests done by Panasonic (and probably most 18650 manufacturers) have a charging rate ranging from 0.5C-1.0C. The 2.25C is way over that and likely will affect the battery life significantly even if it can be safely done. But I do agree that lowering the charging current will easily address that.

    To be fair, the general, most commonly used, definition for "Quick charge" is any significant charge (70+%) that is under an hour. Although there really is no "official" definition.
    http://www.cars21.com/files/news/EVS-24-3960315%20Botsford.pdf

    But I do agree that the charging speed figure that matters the most in the end is the miles/hour (although most people don't realize this, which gives PHEV sellers a chance to brag about how little time it takes to charge their relatively small battery pack).
     
  17. EVNow

    EVNow Active Member

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    There is another thread talking about this. Merge ?

    Options / Pricing gripes for 160 mile version

    BTW, my impression is people getting the 300 mile model are saying it is OK for 160 mile model not to have QC. I'm interested in hearing what people who reserved a 40kWh "160 mile" model think about this. I can't beleive they are happy about this turn of events.
     
  18. qwk

    qwk Model S P2681

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    I don't think anybody is saying it's OK. I think that most are saying it was inevetable due to the smallish pack and battery chemistry.

    I for one think that this is a mistake. Tesla would sell more cars if they offered the supercharger charging at a lower rate for the base cars.
     
  19. EVNow

    EVNow Active Member

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    #19 EVNow, Dec 20, 2011
    Last edited: Dec 20, 2011
    Anyway, as I've explained this is not a technical limitation. This was a purely business decision.

    Ironically, Elon Musk called Nissan's battery "primitive". LOL.

    BTW, I should say I'm always aghast when EVs don't include QC option. I think it is very important to have QC option for widespread EV acceptability. I had the same reaction when news that Focus EV, RAV4EV or Fit EV wouldn't include QC came out.
     
  20. GSP

    GSP Member

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    #20 GSP, Dec 20, 2011
    Last edited: Dec 21, 2011
    The Leaf, the Mitsubishi i, and probably the Spark EV all offer DC fast charging with smaller packs than the 160-mile Model S. I doubt there is a technical reason that prevents Tesla from offering this.

    GSP
     

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