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Supercharger protocol for diy CHAdeMO adapter

Discussion in 'Model S: Battery & Charging' started by nlc, Jul 31, 2013.

  1. nlc

    nlc Member

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    Hello all, I am French, and ordered a model S some week ago (standard 85kWh).

    Here in Europe the charging standard for DC is CHAdeMO, and for now the Tesla is not compatible until they release an adapter, and it will be expensive probably.
    It's why I am searching a way to develop one.
    CHAdeMO interfacing side is easy, everything is well explained on the CHAdeMO website. Now I just need to find the CAN bus protocol used for data exchange between the DC supply and the car, but I will have it soon because I am going to buy the specification.

    Thus to build the electronic interface, now I need to know the protocol used between the model S and supercharger, to be able to simulate it on the electronic interface of the CHAdeMO adapter cable.
    And I really don't know how the Tesla detect the supercharger and bypass the internal charger, and how it sends the current consign to the supercharger, because in Europe the charge port will be a Mennekes type 2 connector, and it just have 2 signals pin, the proximity pin and the control signal pin, same signal than the SAE J1772 standard :

    mennekes.png

    Thus actually I don't know how they will be able to detect the Tesla is connected to a supercharger and directly connect the battery pack to the charge port to do a DC charge.
    Maybe the supercharger will send a PWM with a different frequency value than the habitual 1000Hz ? In this case it's easy for the Tesla to detect it is connected to a supercharger, but how it will send the current consign to the supercharger ? Or maybe the Tesla will not be able to do that and the supercharger will always send its full current, thus only the constant current phase of a charge will be possible in a supercharger, and not the constant voltage phase ?

    If anyone has some idea or information it will be great, have a good day !
     
  2. deonb

    deonb Active Member

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    Is this for a commercial endeavor that you're trying to create?

    If not, this looks like it's going to be at least 100 to 200 hours of work to create this. It seems very inefficient to spend that amount of time to avoid paying something like $2000.
     
  3. arg

    arg Member

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    It is almost certain (from what Tesla have said publicly and from the practicalities of the connectors used) that Model S uses the J1772-DC signalling. This is the same signalling as specified for the Type2 connector in DC mode.

    DC mode starts by the EVSE driving the pilot signal at 5% duty cycle (10% is the minimum used to signal AC current - 10% -> 6A AC, 96% -> 80A AC). Car and EVSE then establish a communication channel using an RF carrier superimposed on the pilot pin. This is confusingly described as 'Power Line Carrier' since it uses the same modulation etc. as the Homeplug system for data over mains wiring, but in this case it is not using the J1772/type2 power pins! This subset of HomePlug is known as 'GreenPhy' and is used for various other applications such as Smart Meters.

    Having established this data link, car and charger communicate details of the charging session using a high level XML protocol specified in the SAE/IEC documents.

    All of this is described in the publicly available documents, though you may find that a full set of the documents is more expensive than a Tesla CHAdeMO adapter! However, you might not need the full set since you can buy modules implementing the GreenPHY layer - in theory you don't then need to know about the lower layers and just need the higher layer protocol.

    So, if Tesla weren't producing an adapter, this would seem like a quite feasible project - but given Tesla's recent promises on availability, it seems unlikely to be worthwhile just to produce something equivalent to Tesla's adapter - for a low volume product or a one-off it will very likely work out more expensive than Tesla's adapter (though admittedly we don't yet know what they are going to cost).

    There may still be merit in third-party ModelS <-> CHAdeMO adapters to produce something different once we see what Tesla come up with - perhaps Tesla's one will be limited to some lower rate such as 25kW in order to keep the size down - in which case there could be advantage in building a full-rate one, or conversely if Tesla's one is full-rate, you might be able to make a smaller one by compromising on the rating. Or other form-factors may be useful - a post-mount adapter for permanent installation next to CHAdeMO chargers, for example.
     
  4. nlc

    nlc Member

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    deonb : don't know yet, for now I try to understand things to see if it's possible to do something or not

    arg : thank you very much for details
    Thus it can be easy to select DC mode if it's just a 5% duty cycle PWM, but the PLC modulation is the problem. Yes it's possible to find chip or module to do the modem low level layer, but the problem will probably be on the high level communication protocol, it's pretty sure that Tesla implemented a proprietary data exchange between the car and the supercharger. And I see that PLC/greenphy chip always embeds AES128 cryptography capability, thus all data exchange are probably encrypted. This way they can be sure nobody can use their supercharger with another car and diy adapter cable...

    With these informations it seems it will be difficult or impossible to a third party CHAdeMO adapter cable for the Tesla :(
     
  5. arg

    arg Member

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    Well, they might have implemented some proprietary extensions, but for basic charging operations there is no reason for them to do so (and good reasons why not).

    There's nothing really very special about supercharging - it's just a high power DC charger: all the clever stuff is in the car and the SAE protocol has everything needed. They've quite possibly got something extra for the car to authenticate itself to the Supercharger (to stop non-Tesla cars stealing the power), - but the car doesn't need to care where the power is coming from so that's not needed in the other direction. Also, Tesla has declared the intent to support SAE DC charging when/if the chargers become available - if that happens, there's nothing to stop you building your own SAE DC charger, which could be in the form of a CHAdeMO adapter (the car doesn't need to know).

    In the meantime, there's a bit of risk that they have (perhaps accidentally) got something in the car's software that makes assumptions specific to Superchargers; that risk becomes smaller when they release the official CHAdeMO adapter.
     
  6. widodh

    widodh Model S R231 EU

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    My only problem with such a connector is: Where does the adapter get it's power from? You will need a microprocessor in there which will need a battery or some capacitor.
     
  7. nlc

    nlc Member

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    CHAdeMO plug has 12V pin and gnd, thus it's not a problem to get power to power the electronic board interface.
    Thus this electronic board will need to simulate a SAE DC charger for the Tesla, and will need to convert the Tesla current consign in CAN message for the CHAdeMO power supply

    - - - Updated - - -

    What you say make sense, if there is a protection, it will be only in the supercharger side to authenticate a Tesla, normally there is no reason the Tesla cannot be charged on a SAE DC charger. But actually without real testing it's difficult to say if the Telsa can actually natively support a SAE-DC charger or not, because supercharger are their own charger, and nothing say us they used standard thing :/

    - - - Updated - - -

    Found that, price is not so high : http://standards.sae.org/j2931/4_201207/
     
  8. rdrcrmatt

    rdrcrmatt Member

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    So I sent Tesla an email today on their "Contact us" section of their website asking about the CHAdeMO adapter. They said there were no plans to make one because of issues with t he CHAdeMO chargers potentially being able to override the Model S's internal charging safety systems.

    bummer.
     
  9. arg

    arg Member

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    Yes, each one is quite cheap, but there are a lot of them!

    You need to start with J1772 itself (the2012 edition covers DC as well as AC - it has the connector dimensions, and the sequence of steps needed to establish/terminate charging).

    Then there's J2847/2 which has the XML for the high level protocol.

    And in theory you need both part 1 and part 4 of the one you referenced above (J2931).

    Then there are more cross-references from those to other documents...

    I have only bought the first two so far.
     
  10. dsmith2189

    dsmith2189 Active Member

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    Not sure where you got your info from but here are the specs for the Tesla CHAdeMo adapter that they say will be available later this year. (don't remember where I got the doc, but probably a link from somewhere here on TMC?)
    Tesla CHAdeMo.png
     
  11. brianman

    brianman Burrito Founder

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    re: dmith's image...

    Interesting to see what looks like an official Tesla statement on "later this year" clearly produced at the time when they were talking about 90 kW instead of 120 kW SCs.

    There are non-Tesla (read 2nd and 3rd handle) articles from September 2012 that already spoke about "future capability of up to 120 kW".
     
  12. TonyWilliams

    TonyWilliams Active Member

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    When will we see 150kW?


    :scared:
     
  13. gregincal

    gregincal Active Member

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    That doc is for Europe. We know there will be a Chademo adaptor for Europe, but that won't work in the US.
     
  14. surfingslovak

    surfingslovak Member

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    Why not? Also, I thought the adapter was primarily meant for Japan?
     
  15. gregincal

    gregincal Active Member

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    European cars have a different connector. Presumably Japanese car will be the same, but we have zero information about the Japanese Model S.
     
  16. rdrcrmatt

    rdrcrmatt Member

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    Someone from Tesla called me back regarding my email.

    - - - Updated - - -

    The tesla rep who called me about my chademo email said the japanese car would not have the same charge port as the US car.
     
  17. nlc

    nlc Member

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    Hello all, just 2 questions :

    - Anyone knows if there is something new about the Tesla supercharger protocol (the exact way the Model S talks to superchargers) ?

    - Anyone knows if there is something new about the CHAdeMO CAN bus protocol ?

    Because the CHAdeMO adapter delivery is delayed, and IMO will not be available before begin of next year. But here in France we don't have supercharger yet, but we have CHAdeMO charger.
    I always think to build one myself.....
     
  18. nlc

    nlc Member

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    Forget this question I just bought the CHAdeMO specification :)

    Just need the Model S / supercharger protocol now :)

    - - - Updated - - -

    As I built my own wallbox, I can easily send a 5% duty cycle, and see on the pilot pin if there is a RF signaling with a scope. Will try that soon as a first step
     
  19. matbl

    matbl Member

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    As previously stated, this is probably the same as used for CCS DC-charging. Powerlink communication on pilot pins. High level protocol is XML-based.
    More details have been discussed in this thread:
    DC charging on type 2 mode 3?
    pages 2 and 3.
    You can also find some useful links there.
    BTW, I'm more interested in a CCS DC <-> Tesla converter...
     
  20. nlc

    nlc Member

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    What are "CCS" charger !? Never heard about this ?

    - - - Updated - - -

    Ok that's Combo.
    I think this kind of "standard" is totaly absord, why not use the pin of the type 2 plug to also do DC (2 pin for + and 2 pin for -), as Tesla do !??

    In your link, it's said that the Tesla is 100% compatible on the protocol (but not physical). If it's TRUE, a CCS adapter for the Tesla is just a physical thing, CSS socket <---> Type 2 plug, to send the 2 DC power pin of the CSS plug to the 4 power pin of the Tesla Type 2 socket
     

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