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When do the twin chargers kick in?

Discussion in 'Model S: Battery & Charging' started by metafor, Aug 7, 2013.

  1. metafor

    metafor Member

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    So I have a NEMA 6-50 installed at home. The theoretical max is 240V/50A, I believe. Now, obviously I'm not going to realistically achieve that but I've noticed that it seems capped at 40A while charging. On the charge screen, it shows 40A/40A (or sometimes 39A/40A). This gives me pause as it appears that 40A is the absolute maximum charging rate. I've not tried to charge at an HPWC or Roadster 70A charger yet, so perhaps it sets that limit based on charger type. Does everyone else with twin chargers see this? Would having an 80A max charge rate allow me to go above 40A (slightly) on a NEMA 6-50 connector?
     
  2. Lloyd

    Lloyd Active Member

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    You are only allowed 80% of the rating for the recepticle for a continuous load. The 6-50 is also a 50 amp recepticle and would be subject to the same 40 amp limitation.
     
  3. metafor

    metafor Member

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    Ahh, so it'll cap you at 80% of whatever the recepticle is? Interesting, wonder how it would detect that anyway considering there's no smart protocol for non-HPWC or Supercharger sockets...
     
  4. Lloyd

    Lloyd Active Member

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    #4 Lloyd, Aug 7, 2013
    Last edited: Aug 7, 2013
    It's in the UMC adaptor for the plug.
     
  5. deonb

    deonb Active Member

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    There is :). The car detects which adapter you have connected to the UMC. If you have a 14-50, the cap is 40a.
     
  6. Cosmacelf

    Cosmacelf Active Member

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    The only way to get more than 40A charge into a dual charger equipped car is through a high power J1772 charger and your J1772 adapter. That and a supercharger, of course.
     
  7. deonb

    deonb Active Member

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    HPWC.
     
  8. Cosmacelf

    Cosmacelf Active Member

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    Sorry, brain fart on my part.
     
  9. Gear

    Gear Member

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    To add to that, can we non twin charger equipped car owners charge at 40A at the high power J1772 chargers? It's my understanding that the Level 2 chargers don't charge at 40 amps. Is that correct?
     
  10. GSP

    GSP Member

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    Most of the public J1772 stations are limited to 30 A. There are a few with higher ratings, like 70 A. If you can find one of those, your single charger MS can charge at 40 A.

    GSP
     
  11. Lloyd

    Lloyd Active Member

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    Level 2 chargers (EVSE's) are rated to charge at up to 80 amps. 30 amps are more common, at least partly because our government, and other car companies, dictated it to be that way.
     
  12. ChadS

    ChadS Petroleum is for sissies

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    And this was despite the fact that the ONLY EV available at the time the DOE awarded the grant was the Roadster which charged at 70A. But they heard the Leaf and Volt were coming and the originally only charged at 15A, so...sigh. That still honks me off. They didn't even say 30A was recommended; they said L2 installed with federal money COULD NOT be higher than 30A.

    The DOE has admitted they screwed up (though they won't say who made the mistake; I assume it was set that way on automaker - not Tesla, obviously - advice) and they will consult with owners next time. There have been a lot of silly infrastructure mistakes that could have been avoided if people would have contacted Plug In America some time before sending an invitation to the unveiling ceremony. Fortunately as the market picks up we are getting more early contacts.
     
  13. Cosmacelf

    Cosmacelf Active Member

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    @ChadS - that's very interesting. I always wondered how we ended up with a pseudo standard of 30A charging. I can totally see the big auto companies intentionally sabotaging the process. More charitably they probably took a line that cheaper charging stations would translate into more charging stations being built. The tragedy, of course, is that, especially with expensive commercial chargers, the cost from going to 30A to 80A is only a small percentage of overall cost.
     
  14. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    Notwithstanding the receptacle limitations mentioned earlier (40A continuous load limitation on 50A circuit), even if you had an HPWC capable of doing 80A you would still not be able to get 41A into a single charger at 240V (9.84 kW).

    This can get confusing, but the bottom line is that Tesla's chargers are limited by current (amps), not power (volts x amps), and a single charger is limited to 40A regardless of input voltage. This is because the current-carrying capacity of a piece of wire or a trace on a circuit board is determined by current alone. However, charging times and energy consumption are all based upon power, so Tesla simplifies it and makes an assumption of 250V in its calculations, hence 250V @ 40A = 10 kW.

    From a pure rating standpoint, Tesla's single charger is capable of doing anything from 3.4 kW (85V) to 11.08 kW (277V), and it depends upon your input voltage. If you only have 240V, then you are limited to 9.6 kW with a single charger.
     
  15. Lloyd

    Lloyd Active Member

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    And to continue in this...... It's up to US as Tesla owners to DEMAND the higher power EVSE's or it will not happen!! I would like to see Malls, Hotels shopping etc. installing HPWC's. They are cheaper than a clipper creek unit that is typically installed, and they look better!

    Tesla should offer a discount to HPWC's that will be installed for free public use, in public locations.
     
  16. Gear

    Gear Member

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    I can't see that happening. HPWC's can only be used by Tesla owners, right? There are lots of other EVs out there.
     
  17. gnelson

    gnelson Member

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    Wouldn't it be a good idea that the twin chargers could be implemented even at low amperage to minimize temperature effects on the battery.
     
  18. Puyallup Bill

    Puyallup Bill Member

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    And, the Roadster HPC at 70 Amps with an adapter.:wink:
     
  19. capt601

    capt601 Vin02324

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    But tesla owners are not buying the cheapest EV or hybrid EV's out there. They normally have the money to spend on things or food while they are charging. And are not just looking for a free ride.
     
  20. bluetinc

    bluetinc Member

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    Hey ChadS,

    I have heard that a number of times before, and I've repeated it a few times myself. Do you happen to have a pointer to it in some government doc? I'd love to be able to pass that document along during some discussions.


    peter

     

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