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Twin Chargers: Why?

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

  1. smorgasbord

    smorgasbord Active Member

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    Am I missing the advantage(s) of the Twin Chargers option? I don't see any:

    20KW means something like 90amp delivery, which means over 100amp circuit breaker. You're not going to find those on the road, so it's only for home, where you've probably got enough time to charge at the usual 40/45 amps.

    For Supercharging, we apparently don't need the Twin Chargers, just the 85kWh battery. That's what we'd target for long road trips.


    So, why get the Twin Chargers? This is reason alone for me to not upgrade to a Signature model (don't want to pay for options I won't ever use).
     
  2. markwj

    markwj Moderator, Asia Pacific

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    I guess that is the reason why they split it (10KW+10KW).

    With the roadster, everyone has it, has to pay for it, but most don't (or rarely) use it. Making it an option is a good compromise, imho.
     
  3. clea

    clea Member

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    i was thinking the same thing ...

    I now need to spec out the car without the options given by the signature that i don't need and think about if i want to downgrade or not ...
     
  4. Kevin Sharpe

    Kevin Sharpe Active Member

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    We already have a number of HPC's charging at 60A and 70A in Hotels and similar locations in Europe... I use the UK HPC network to undertake long distance trips and to extend range... no reason why you shouldn't do the same (assuming you can get HPC's installed) :wink:
     
  5. AnOutsider

    AnOutsider S532 # XS27

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    isn't the 20kw option needed for the HPC? Maybe I need to go back and re-read the page
     
  6. PopSmith

    PopSmith Saving for a Model 3

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    The HPC just says "with a power supply of up to 20kW". Since it says "up to 20kW" I think that means it will work without the Twin Charger option.
     
  7. dsm363

    dsm363 Roadster + Sig Model S

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    I'm not sure if it's required but you couldn't charge any faster than the standard 240 included charger.
     
  8. GSP

    GSP Member

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    I would consider the Twin Chargers if I was buying a 160-mi car. For some unknown reason Tesla is not supporting DC fast charging on these. The 80-amp TwinChargers allow you to add range at about 60 mph, instead of "only" 30 mph for the 40-amp standard unit. When on a road trip this will be well worth the TwinCharger price.

    You will have to find a 70-80 amp EVSE to take advantage, but Tesla might sell an adaptor for the "Tesla" (Roadster) stations in California, and maybe some 70-80 amp J1772 stations will spring up. Even with 80 amps only available at home, you could add extra miles after work, or when running multiple errands during the weekend. This is more likely to be needed with shorter range cars, and during the winter.

    That said, 30 mph, 40 amp, charging will be plenty for me, and probably 99% of the population, except when on road trips.

    Note that DC fast charging will allow 320 mph! This is an order of magnitude less than a gas pump, which can "recharge" at about 3000 mph. However, this will be all that is needed to almost completely replace gas cars, I think.

    GSP
     
  9. Todd Burch

    Todd Burch Electron Pilot

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    I agree, GSP. With the expected nationwide supercharger network, I think Elon may truly be putting the range anxiety question to rest...or at least we're on the very verge of that!
     
  10. TEG

    TEG TMC Moderator

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    I would assume that a car with only 10kW charger could plug into an HPC and charge at 10kW even if the HPC was configured to allow higher levels.
    Basically the EVSE offers a possible level, and then the charger in the car draws as much current as it can _up to_ that level. So basically, lowest common denominator.
     
  11. Todd Burch

    Todd Burch Electron Pilot

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    I mentioned this in another thread, but I believe Tesla is restricting base pack access to the Supercharger for business reasons, not technical reasons.

    Force users to upgrade to help subsidize a nationwide charging network.
     
  12. Mycroft

    Mycroft Life happens

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    I disagree Todd. I think it's because of technical reasons. The supercharger only works to fill the batter half-way in 30 minutes and that's if the battery is completely empty. So in the real world, the 160 mile battery would be down to 20 miles charge and the supercharger would only be able to toss in about a 60 mile charge in 30 minutes. Not quite what the intention of having supercharging stations every 150 miles or so.
     
  13. smorgasbord

    smorgasbord Active Member

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    I think (almost) all the public Tesla stations are now J1772 equipped, many at 70 amps. So the Model S's standard J1772 adapter should work fine.
     
  14. richkae

    richkae VIN587

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    Here are several reasons to buy the 2nd onboard charger, none may apply to you:

    1) You have a small fleet of Model S cars. You know that your usage model does not require charging faster than ~20kW, nor do you want to spend the money installing your own Superchargers. However at $1500 per car, fully utilizing your own ( very inexpensive ) ~20kW AC hookups is total worthwhile.
    2) You are a private owner, you know you will make one or more specific trips that are unlikely to be served by Superchargers on a regular basis and it is worth your while to install your own ~20kW charger ( HPC ) on the route.
    3) You believe that publicly available ~20kW level 2 chargers will be more plentiful than Superchargers ( or plentiful enough to be useful ) in the future.
     
  15. EVNow

    EVNow Active Member

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    #15 EVNow, Dec 20, 2011
    Last edited: Dec 20, 2011
    That is still a business decision - not a technical one.

    It should be technically very easy to achieve a 40kW charging of the 40kWh pack @ 1C. That would give a decent "80 mile" range boost in 1/2 hour - enough for me to go to Vancouver or Portland from Seattle.

    BTW, I should say a 20kW charger for the 40kWh car, would come in quite handy even if SuperCharging is not allowed.
     
  16. NielsChr

    NielsChr Member

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    is there something about the regen is using the cars built in charger to put the energy back into the batteryes ? - if so, the regen can be more effecient if a 20 kw charger is onboard - potentially giving a longer range....I don't know, maybe others know how roadster handle this
     
  17. bolosky

    bolosky Member

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    I'm not quite sure how the Roadster handles it, but max regen is ~36kW, and the fastest charging you can get is < 17kW (240V x 70A). So, either it's got a bigger charger than it needs for plug-ion charging just to do regen, or else it's doing something else.

    10kW regen on a heavy car like the S would be really wimpy.
     
  18. Robert.Boston

    Robert.Boston Model S VIN P01536

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    I would love to know whether Tesla can retrofit a Model S with a second charger after delivery. Currently, I see no need for one. But if the world evolves to have a lot of 70A public charging stations, I'd hate to be limited to using just half that capacity. Nearly all the public chargers around New England, however, are all below the 10kW mark, so currently I would never have any use for the second charger.
     
  19. dpeilow

    dpeilow Moderator

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    Often a device (charger, wire, etc) can operate at over rated power for a few seconds without overheating or destroying itself. That's enough for braking. However long durations require it to be used at a lower power.
     
  20. ljbad4life

    ljbad4life Member

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    Tesla restricting access to super chargers probably has to with the warranty. traveling and fast charging a 160 mile battery puts a lot more cycles on it than a 300 mile pack (traveling the same distance). Ex: I have a 300 mile pack, I travel NYC->Boston. A 160 mile pack would have to charge 1-2 times. while a 300 mile pack would have to charge 0-1 time. The longer the trip the number of super charges become multiplicative. Boston->DC 300 mile pack super charges 1-2 times while 160 super charges 3-4 times. The super charging really adds up for the 160 and that's what Tesla wants to avoid. Li-ion battery packs have a cycle life. So to provide a warranty of 8 years would require them to sacrifice the super charging.
     

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