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AC vs. DC fast charge

Discussion in 'Charging Standards and Infrastructure' started by Kane, Nov 11, 2012.

  1. Kane

    Kane Member

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    Hello,

    FIRST

    As You probably know Renault Zoe have 3-phase 43 kW onboard charger.
    smart for two electric drive have about 3 kW onboard charger. Optional 3-phase 22 kW cost about $3500.
    Tesla Model S have 10 kW onboard charger. Optional upgrade to 20 kW cost about $1500

    So in smart, upgrade from about 3 to 22 kW -> 19 kW for $3500 = $184/kW
    In Tesla Model S, upgrade from about 10 to about 20 kW -> 10 kW for $1500 = $150/kW

    Lets say onboard charger in Renault Zoe cost $150/kW.
    43 kW charger in Zoe cost then $6450!

    Lets say optimisticaly it cost only $100/kW.
    43 kW charger in Zoe still cost $4300!

    Few thousands is about 25-30% of its price without battery. So, Zoe with 3 kW charger should have even few times more sales. Why they didn't chose small onboard charger?

    SECOND

    If fast DC charge (50 kW CHAdeMO or other standard) cost about $10 for use to be profitable how many uses can buy for $5000 instead of high power onboard charger? 500? Once a week it means 10 years! And I still have money on begin, less weight of the car, etc.

    THIRD

    If You even have higher power onboard charger, what will be the cost of use it? I think also about $10 because costs of power is similar. You have 3 times cheaper AC terminal then DC charger but often it will not be used with optimal power. Ex. 43 kW terminal and charging 22 kW smart or 3 kW smart. So the price of use will be same.

    FOURTH

    If EVs are future. Lets say 1 milion EVs. You need 1 milion x $5000 for 43 kW onboard chargers to give all chance for fast charge. It is $5 000 000 000!!!
    Alternatively for 1 milion EVs You can build 10 000 DC chargers for $30 000 each (15-20k for charger and 10k for instalation). It will cost $300 000 000. 16x less!!!
    More EVs on the market, more sense is for DC infrastructure. Do calculations for 10 milions and You will see.

    FIFTH

    Even low power AC charge points don't have economical sens. Less energy sold, higher price must it have - 3-4x more than average energy cost in household.

    AC fast charge, especially with power over 20 kW is no brainer for me. Good that Tesla selected DC 90-120 kW. 10-20 kW onboard for private use in home is ok because big battery packs.
     
  2. jkirkebo

    jkirkebo Model S P85+ VIN 14420 EU

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    I'd like a 22kW charger (at least) for the Model S as 32A 3-phase outlets will be much more plentiful than SuperChargers around here. Even though it's slower, it's still fast enough to be useful in a lot of scenarios.
     
  3. Johan

    Johan Took a TSLA bear test. Came back negative.

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    The big question(s) I think are:
    1) How much heavier is the Zoe for having the 43kW charger ("Chameleon charger") and
    2) How much more expensive is the 43kW charger compared to say a 6.6 kW or 10kW charger the way that Renault has constructed it?

    If the answer to 1) is a substantial weight increase and the answer to 2) is it makes the car a lot more expensive then I agree with you it's a bad idea (However, I think the expression "no brainer" actually means that it's a good idea, one that is so obviously good that it can't even be disputed). If it on the other hand is cheap and light then it makes a lot of sense to include it with today's infrastructure. One point you mustn't forget is that AC plugs will "just work" as long as the power is on while any form of DC charger will be a lot more complex and prone to different problems and issues. This is something we have a lot of real life experience with - just read on any domestic EV forum about how people often come across DC chargers that just are not working for a myriad of reasons.
     
  4. Kane

    Kane Member

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    Someone know how much Chameleon charger cost?
     
  5. Fernando M

    Fernando M Member

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    #5 Fernando M, Nov 12, 2012
    Last edited: Nov 12, 2012
  6. Kane

    Kane Member

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    150 €? If this is so cheap and brilliant why others not using it?
     
  7. Fernando M

    Fernando M Member

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    Because is a Renault patent.
     
  8. Bipo

    Bipo Member

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    In fact its cost is zero, because either you choose fast AC or fast DC the price is the same (+150 €). In one case is the charger, in the other is the CHAdeMO plug and wiring.


    IMHO, AC is briliant for under 50 kW and DC for ultra-quick charge (over 100 kW). The Combo 2 plug is the perfect choice indeed.
     
  9. Kane

    Kane Member

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    I don't belive You. Simple inlet for Type 2 cost more than 150 €. If they modified controller to use its power modules for charging it's not trivial thing and will not cost 150 €. AC Propulsion did Reductive Charger several years ago, and Tesla not implmenting it in Model S for some reasons I guess. So real price can be hidden in controller (if they really don't have speparate onboard charger).
     
  10. Bipo

    Bipo Member

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    Just look at the image above. I don't guess, I read. If it's wrong or not, I don't know.

    The Camaleón charger is briliant. I guess (now I do) that it uses the regenerative braking rectifier to rectify the input AC. Zero aditional cost.
     
  11. Kane

    Kane Member

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    It's not bad idea and this is not new idea to use inverter. It's patented and have some isolation issues. If they licenced it or developed, I think it will cost more thant 150 €. You even can't buy plug for 150 €.

    "Before Tesla had developed the Roadster's proprietary powertrain, the company licensed AC Propulsion's EV Power System design and Reductive Charging patent which covers integration of the charging electronics with the inverter, thus reducing mass, complexity, and cost. Tesla then designed and built its own power electronics, motor, and other drivetrain components that incorporated this licensed technology from AC Propulsion.[SUP][35][/SUP][SUP][36][/SUP][SUP][37][/SUP] Given the extensive redevelopment of the vehicle, Tesla Motors no longer licenses any proprietary technology from AC Propulsion. The Roadster's powertrain is unique.[SUP][38][/SUP]"
    Tesla Roadster - Wikipedia, the free encyclopedia

    SourceForge.net: Charger - tumanako

    Ok. Other want few thousands for charging higher power for some reasons. Tesla not using it any more. I'm looking foward to know why.
     
  12. Bipo

    Bipo Member

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    Another explanation that I heard about the Chameleon is that it uses the wound motor to convert AC into DC... That can explain why neither the Leaf nor the Model S can use this method, as long as they use a permanent magnet rotor, not a would one.
     
  13. Johan

    Johan Took a TSLA bear test. Came back negative.

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    S is wound induction motor, not permanent magnet...
     
  14. Bipo

    Bipo Member

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    I've checked the Tesla web and the Model S has neither a permanent magnet nor a wound rotor motor, but an induction squirrel-cage rotor. Anyway, as it has not a wound rotor, it is not compatible with the Chameleon technology from Renault (if it works as we suspect, using the motor to rectify AC into DC).
     
  15. Johan

    Johan Took a TSLA bear test. Came back negative.

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    Ok you're probably right, but I would argue that the Model S motor has to have wiring that is somehow wound, since it can create a rotating magnetic field by running current through it. The design wouldn't really matter that much would it?
     
  16. Bipo

    Bipo Member

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    Obviously an electric motor must have a wound wiring in the stator, so it can create the rotating magnetic field, but the rotor is a different case. The synchronous motor can have a permanent magnet rotor or a wound one. The induction motor can have a squirrel-cage rotor or also a wound one. The difference is that in the synchronous motor the wound rotor must be feed with DC but in the induction motor it must not be feed at all, only should be self-connected through an impedance (or without impedante at all, that is the same case of a squirrel-cage design).

    The main advantage of a wound rotor is that makes possible the perfect control of the magnetic fields of the rotor, so you can get the optimum torque and performance in every scenario. The cons are that you need rotating contacts (friction rings) to feed the rotor wires. That means a more complex design, with friction parts and more expensive maintenance. But the advantages IMHO make it worth it.
     
  17. Kane

    Kane Member

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    To rectify 3-phase current with different power levels (11, 22, 43 kW) You need 6 power transistors bridge - power modules from inventer with PWM. No matter what type of motor it have (of cours 3 phase stator motors). In my opinion modifications will not cost 150 €, and I see some drawbacks (insulation, voltage level, some motor rated contactor in they way = less efficiency when driving).
     
  18. Johan

    Johan Took a TSLA bear test. Came back negative.

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    We can at least agree that the engineers at Tesla are probably the best in the industry and I think they have good reasons to have chosen the motor design that they have chosen (the car and it's performance is the living proof of that!) even if this design does not let them use the motor/inverter as an AC to DC rectifier, but instead they need the separate charger unit for this. Remeber they have chosen the modular design where each charger is 10kW and you can stack 1 or 2 in the car and you can also stack 12 of them and make a 120kW Supercharger! This modular design gives you a lot of gains in easy manufacturing and economics of scale.

    Also, to come back to the original post, I think that high power DC charging makes the most sense for fast charging while AC charging is for home use where you usually have the night to charge so 10 or 20 kW is enough even with the big battery. With the big batteries that Tesla is putting out even 43.5 kW of charging (400V/63A 3 phase which is the maximum input for the Zoe) is too slow for true "Fast charging". The one setting where you want to use this if for long road trips, and then to wait even just little over one hour for the battery to fill up is too slow, I think Tesla is doing the right thing with the 90kW (future 120kW) superchargers for road trips.
     
  19. Bipo

    Bipo Member

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    #19 Bipo, Nov 13, 2012
    Last edited: Nov 13, 2012
    But all those transistors exist already because, as long as the Zoé has a wound rotor, it needs P.E. to feed the wires in the rotor!! So the additional cost should not be very high.


    IMO, Tesla has chosen the induction motor with squirrel-cage rotor because its extreme reliability: it is rock solid an has no friction parts. In addition, there is no three-phase distribution in USA as we have here in Europe. In the States the most extended voltage is 240 split phase, but here we can get 400 V x 3 almost everywhere. So for Tesla AC fast-charge was not a priority as long as in USA is not useful.

    In the other hand, Renault has developed the optimum system for the Old World, where you can deploy a very affordable AC fast-charge grid to feed also affordable cars. Here in Europe, DC charge makes sense for highway routes only, and always using power levels over 90-120 kW (the target must be to get +10 km range for each minute you're plugged). Here is where the Combo2 plug makes sense, allowing both low-mid-fast AC charge (3.5/7-11/22-43 kW) and ultrafast DC charge (90-120 kW).

    Tesla has designed the charging system for America, nor for Europe, it's obvious: Tesla plug CANNOT manage three-phase.

    So, returning to the topic, my bid is:

    America: AC 3.5 kW (120 V), 3.5-7-10 kW (240 V) and DC 20-50-90-120-150 kW (400-800 V).
    Europe: AC 3.5-7 kW (230 V x 1), 11-22-43 kW (400 V x 3) and DC 90-120-150 kW (400-800 V).

    IMHO Tesla and the other companies will be pushed by the market to offer three-phase charging up to 43 kW in Europe, I have no doubt.
     
  20. Johan

    Johan Took a TSLA bear test. Came back negative.

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    @Bipo I agree with all of the things you are saying. There has been some good discussion about the 3-phase problem with the connector, possible solutions both with regards to the plug, inputs and charging, in the 3 phase charging for Europe thread.
     

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