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Tesla Model S wiring diagram (for alarm and range extender)

Discussion in 'Technical' started by nlc, Jan 14, 2014.

  1. nlc

    nlc Member

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    Hi, Anyone knows if the wiring schematic diagram is available somewhere ? I need it to be able to easily implement some add-on in the car.
    I receive my model S in less than 2 month and want to install an anti car jacking and home jacking system.

    And I also work on a range extender for the Model S (20-25kW), need to see if I will be able to send DC current in the car without perturbating the battery SoC calculation.

    The idea is to never charge the battery (the range extender stops generating current when the battery current becomes negative), but try to maintain the battery current to zero. This way, all 0-20kW power demand from the inverter will be compensated by the range extender, and the battery pack will see no current consumption.

    Theoretically the current injection will not perturbate the battery pack SoC, because I want to connect directly to the DC bus of the inverter, this way the current I inject will not pass through the battery pack current sensor :smile:

    Anyone has a photo or something to see how the 400VDC bus arrives to the inverter ?
    Regards
     
  2. tom66

    tom66 Member

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    There are some teardown pics around the inverter area showing the HV cabling is direct from battery to inverter.
    If you interrupt this and inject your own, you will be stuck with crappy 25kW acceleration. It will do 0-60 never!
    It's not safe to bypass the charging circuitry. You need to use onboard charger. But they don't work in Drive, so you'd need to trick it into charging while moving.
    Long story short you'd be better modifying something like a Prius….. yeah it might not be as sexy but it's been done before.
     
  3. nlc

    nlc Member

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    the goal is not to replace the pack, but connect the range extender in parallel on the inverter's DC bus and inject current when the inverter need. In other word, the pack current will be the inverter current minus the range extender current. Thus it will not change the 0-60 perf ;)
     
  4. nlc

    nlc Member

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    I searched the forum but unfortunately I don't found anything :(
    Any idea where they are ?
    Regards
     
  5. CroDriver

    CroDriver Member

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    This won't work with bypassing the battery-pack. The ICE won't be able to supply the power when the inverter demands is. I.e. the ramping-up and ramping-down of the range-ex is too slow for the electric powertrain. You need some kind of buffer in between.
     
  6. qwk

    qwk Model S P2681

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    You won't find any wiring diagrams, because Tesla doesn't share any information about anything technical. If you wanted to implement what you are asking about, reverse-engineering and new code will be the only way to do it. Not to mention it will void your warranty.
     
  7. nlc

    nlc Member

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    #7 nlc, Jan 14, 2014
    Last edited: Jan 15, 2014
    As I said, the Rex will be in parallel on the inverter dc bus, thus the buffer is the 85Kwh battery pack...

    - - - Updated - - -

    I was talking about pics of the inverter where we maybe can see some wirering, it can helps a little
     
  8. nlc

    nlc Member

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    That's OK, I found what I was looking for, in the emergency response guide :

    Capture-7.png

    We can access easily to the DC bus of the can in the high voltage junction box. The DC bus from battery pack enters this junction box and is dispatched to the 2 chargers, the inverter, and the DC/DC 12V power supply.

    I just hope there is only one current sensor inside the pack for the SoC calculation, and that's not each peripheral (inverter, dc/dc/charger) which measure how many amp they draw/inject from/to the battery pack, and inform the main ECU which does the global calculation :crying:
     
  9. tom66

    tom66 Member

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    #9 tom66, Jan 16, 2014
    Last edited: Jan 16, 2014
    I am pretty sure that the inverter and battery computer will be constantly talking to each other. I have heard, I do not know if it is my imagination, that the contactor in the pack, on 60kWh, clicks when you regen. So there is at least that. It probably will do a "Car Needs Service" message if you make the current imbalanced.

    If you do get it working, I predict fire when your Rex overcharges the pack.

    And dear god WHY? WHY would you take the BEST pure EV car out on the market now and stick a dirty, noise, inefficient gasoline engine in it???
     
  10. mnx

    mnx 2013 P85

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    Good luck with your project. I love that some people are willing to mess with their cars.

    How are you planning to generate 20-25kW of power? A giant towable generator?
     
  11. nlc

    nlc Member

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    That really curious, I developed some inverters and there is no reason for that. Regen cycle appear each time you leave the foot from the pedal, it would be curious they commute a contactor each time, and I see no reason to that !?

    Will not happen, because I will configure the Rex to work as a voltage generator with current limit, and with a max voltage lower than a full battery pack voltage. For exemple 380V. It means the Rex will only be able to push current when the cell will at 3.8V, thus absolutely no possibility to overcharge the pack.
    And also, I plan to only inject current when the inverter consumes current, and never when it consumes no current (car stopped) or during regen. In other word, the Rex will never inject current to charge to pack.

    Maybe yes, maybe not. There is no reason they compare the battery current and the inverter current. The main Ecu probably send current or regen current consign to the inverter, based on multiple information (throttle, pack temperature, pack SoC, etc...). If the current sensor for the SoC calculation is in the pack, current injection on the DC bus will not perturbate the SoC calculation.
    And if I inject current only when the inverter consumes current, the pack will see less current consumption, and SoC will decrease slowly.

    But I will be able to conclude if there is a chance to work when I will receive the car and do some verifications.

    That a good question, and the answer is that for now in France we don't have SC, and before all the SC will be installed (winter 2014 normally, thus up to march 2015 !!), I have multiple big trip to do (>=1200Km) with very short delay and thus no possibility to wait 3 time 4 hours to charge on a 22kW public charger.
    And I prefer do my trip in Tesla with a Rex rather than do these trip with an infamous gasoline car :scared:

    - - - Updated - - -

    Thank you :wink:

    Yes absolutely, with this power at stabilized speed there is no range limit.
    I found a good motor candidate, a 800CC bi-cylinder, with electronic injection. Its weight is 45Kg, and I will have approx 15-20Kg for the generator.
    The problem with the Tesla is that normally it is not allowed to tow. A hitch exists but here in France it will be illegal to use it and have a trailer, because on the car official paperwork the authorized total weight of car + trailer location is empty :cursing:
    Thus my options are to suspend the Rex at the rear of the car, or to mount it on the roof rack....
    But on the roof rack, than maximal authorized weight is 75Kg. This is not huge, but maybe doable....
     
  12. VolkerP

    VolkerP EU Model S P-37

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    If you honor your time at $25 per hour, I predict it will be cheaper to buy 2 extra Model S and swap empty with full car along your planned 1200km trip than doing this rex project.
     
  13. mnx

    mnx 2013 P85

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    Or the OP could fly? :)
     
  14. nlc

    nlc Member

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    Certainly not ;)
    2 more Tesla = 234,000$, thus 9350 hours of work :rolleyes:
    Don't worry about my time, I am an ardent developer and I love what I am doing thus my time is free :biggrin:
    And I don't want to do a one shot work, this kind of industrialized Rex can interest a lot of people IMO. From my actually calculation an industrialized version of this Rex can be sold for <6-7,000$
     
  15. tom66

    tom66 Member

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    #15 tom66, Jan 16, 2014
    Last edited: Jan 16, 2014
    Other concerns are that the battery cannot be charged AT ALL below about 0°C and how will your Rex cope with a sudden deceleration - a genset takes considerable time to spool down and could overvolt the pack if near peak SOC at low temps. (Cell voltage falls with temperature.)

    If I were to do it (and I wouldn't, but...) I'd look at the comms interface between BCM (body control/electronic module) and charger.

    There's probably a simple inhibit signal over the CAN BUS which is sent when car is in DRIVE, and also a hardware interlock (pack relays, etc.) You could feed 230V AC into it if you could trick the chargers into running while the car is driving and get up to 22kW charging.

    Problems I see:
    - the chargers may be most displeased about sudden pack SoC and voltage changes due to acceleration causing it to go to a safety abort
    - the chargers may time out after the charge has not finished for some time
    - cell balance may not be possible / may be inaccurate during high discharge - possibly to damage battery or cause fires
    - there may be some reverse interlock: ECU cannot drive while charging, rather than the chargers cannot charge while driving... that could be a LOT harder to overcome.

    It is known the Tesla can use shore-power, allowing it to AC from the chargers by keeping pack SOC constant. However, that may be reliant on the load being less variable than say, the drive inverter, which can swing from <1A to over 1,200A in under 2 seconds.
     
  16. nlc

    nlc Member

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    As I said, the Rex will have a limited voltage output of 380V for example, it will never be possible to overcharge. And it will never inject current if the invert don't draw current.
    The Rex will be very fast to stop injecting current because the rpm range between no current and full current will be very narrow (Maybe between 100 and 200rpm), thus the Rex throttle will be like a torque control, and output current reaction can be very fast.

    No, probably not. I think the chargers are just slaves and listen for instructions and current consign from the main ECU, which calculate charging current with a lot of parameters (pack temperature, etc...). That's the best possible architecture because they just need to update software of the ECU, not the charger firmware if they need to change or update algorithms.
    Be able to have the inboard charger working during drive is IMO the best way to have a warning or an error on the dashboard :eek:
    Because we need to bypass the ECU consign to charger and replace them by our own.

    Thus I totally forget this idea because it needs hacking of the Tesla CAN bus and/or embedded software, IMO direct current injection (only when inverter draws current) on the DC bus is the best way. But this will work only if the current sensor for SoC calculation is integrated in the pack (it will see less current out of the pack during current injection on the DC bus and SoC will just lower slowly).
     
  17. tom66

    tom66 Member

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    There's definitely a master and slave charger so it makes at least some sense that the chargers are automated, but I don't know for sure.

    Also, how quickly can the Tesla go from 310kW (with Rex pumping +20kW) to 0kW (regen disabled in cold?) Let's say less than a second? Can your Rex really spool down from 20kW to 0kW in that time?

    Injecting 380V is not the issue. The cells simply CANNOT be charged at low temperatures - doing so can destroy them. If you do even slight charging you plate metallic lithium on the cells, risking severe damage and fire.

    Please, have a sign on your car "Modified Hybrid Tesla - Fire is my Fault" because the LAST thing Tesla needs is more fires because you try this crazy idea.

    The other question is, how will you handle the situation of the inverter power being modulated with battery SOC? As battery discharges peak duty cycle increases - how do you avoid over loading the Rex if your battery SOC is low?
     
  18. nlc

    nlc Member

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    Yes

    The pack temperature is regulated and will never be under 0°c during driving

    There will be no fire, don't worry, electronics and power electronics is my job, I exactly know what I am trying to do ;)

    The Rex will have the same behavior than a voltage supply with current limit (CC/CV), thus the Rex cannot be overloaded
     
  19. tom66

    tom66 Member

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    Pack temperature isn't that well regulated - hence why regen is disabled below about 0°C and inhibited below about 20°C.

    Power drives are my hobby / field of study, I've only built one rated for about 100W brushless so far though.

    You seem to be convinced that you can do what you say so go for it, but be very careful with what you do.
     
  20. nlc

    nlc Member

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    Anyway, the Rex will be fast enough to cut current injection if battery current is zero or negative (regen from inverter)

    Mine too, and I am lucky I worked/work on really interesting project, as this one : Global Website - E-Fan
    I build for them the 2 lipo battery pack ( 2 pack of 60 cell 40Ah kokam), developed and integrated the specific BMS, and developed and integrated the 2 very specific inverters for the two AC motors :smile:

    That's clear that if I have any doubt, I will do nothing, don't want to break my beauty :love:
     

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