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Help with VehicleLogs concerning SOC

Discussion in 'Roadster' started by ThomasRoadster, Feb 27, 2016.

  1. ThomasRoadster

    ThomasRoadster New Member

    Joined:
    Feb 27, 2016
    Messages:
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    Location:
    Mannedorf, Switzerland
    Hi

    I am thinking about buying a Tesla Roadster Sport, had a look at it this week and downloaded the vehicle logs. Thanks for the desciptions on how to do that and how to understand them. Had a look at the log files and the SOC seems to top off at about 85%. Is this due to some sort of limitation in the charging process or is it due to battery capacity? I would very much appreciate comments on this from experienced roadster owners. If of any help, I can provide the log files.

    Best regards from the hopefully soon to be Roadster Owner
    Thomas
     
  2. slcasner

    slcasner Member

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    Location:
    Sunnyvale, CA
    It depends how you are seeing the SOC. My first guess is that what you are seeing is the level achieved by a Standard mode charge rather than a Range mode charge. The Standard mode charge intentionally does not fill the top 10% of the battery because doing so causes more stress on the cells. The battery display in the car is expanded so that this 85% charge is displayed as 95%, which is the normal result after the charge is complete and has settled.

    In Standard mode the bottom 10% of the battery is also reserved, again to reduce stress on the cells. The display goes to zero when that 10% still remains. If you are driving and have not quite reached your destination, you can switch to Range mode and the display scaling will be removed so you see that 10% available.
     
  3. thefortunes

    thefortunes Member

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    Location:
    Wisconsin
    What do the logs show as the CAC? Ideal miles after a standard charge (the 85% you are seeing)? What is the mileage, age, etc...? (We can help you evaluate if you give us a little more info).
     
  4. djp

    djp Roadster 2.0 VIN939

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    Aug 28, 2011
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    Location:
    Toronto, Canada
    Don't worry about the 85%, that's the normal level for a Standard Charge. A Range Charge will bring it up to 95%. The best measure of battery health is the Calculated Amp hour Capacity (CAC). As a first step, use Tom Saxton's parser to extract a summary of the log file.

    VMS Log Parser for Tesla Roadster

    There will be one section with the heading "timestamp, brickahmin, brickahave, bricknumber". The brickahave is the CAC. The highest possible value is 160, anything over 155 is like new. The table will show you how the CAC has varied over time and which brick has the lowest capacity.
     
  5. ThomasRoadster

    ThomasRoadster New Member

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    Feb 27, 2016
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    Location:
    Mannedorf, Switzerland
    Thanks a lot. I hoped it was something like that makes absolutely sense with the charging. Unfortunately I can't (yet) try everything, since the car is located some distance from where i live. But I will have a closer look once it is mine :)
     
  6. ThomasRoadster

    ThomasRoadster New Member

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    Feb 27, 2016
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    Location:
    Mannedorf, Switzerland
    Here is some additional info: mileage is about 23'000 km (14'300 mi), age of car is about October 2009. VMSparser run on the vms_log file shows CAC approx. 150.94 Ah. Very cool tool. Is there some sort of 'man' page for options available? I only found the explanations on the log file, but not on the parser itself. Couldn't locate the section with the headings "timestamp, brickahmin, brickahave, bricknumber". Thanks for your time, it is very much appreciated
     
  7. gregd

    gregd Member

    Joined:
    Dec 31, 2014
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    VMSParser -? will give you the options supported. You might try the -p option to see what sorts of alerts (not necessarily errors) the car has thrown in the past. The causes may have been reasonable, or the issue fixed, but perhaps something to discuss with the current owner. Don't get alarmed by the length of the list (mine is over 10.000 lines!), just scan for ones that might indicate a deeper issue with the power train, charging, or cooling system.

    Many of the items listed are described here: Roadster - Tesla Motors Club - Enthusiasts & Owners Forum

    Sounds like the car, or at least the battery, is in fine shape. After 32k mi, my CAC is around 146, so you're right on track. Enjoy!
     
  8. ChargeIt

    ChargeIt Member

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    Mar 1, 2016
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    Location:
    Chandler, AZ
    We recently purchased a 2008 Roadster, and I attempted to download the logs. I followed the instructions on Tesla's website to start the logging, but when I plugged in the USB stick nothing happened. No notice on the display and the LED on the stick never lit up. Is there any other trick to start the download, or any test to know whether or not the USB port is defective or doesn't like my stick? I've tried a couple different 4GB SanDisk sticks.
     
  9. slcasner

    slcasner Member

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    The USB stick needs to be 1 or 2 GB with a FAT16 filesystem and the root directory must contain a subdirectory named VehicleLogs.
     
    • Like x 1
  10. wiztecy

    wiztecy Active Member

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    Also the system / usb driver that loads the usb stick can act up if slcasner's recommendation above didn't work. With that the the plugs on the VMS need to be removed and plugged back in which causes a full hard reboot of the system. If you're not handy working on things you can just take your Roadster into Tesla and they should be able to help you.
     
  11. triakter

    triakter Member

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    Jan 24, 2016
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    Location:
    SLC, UT
    Thank you for this note. I had been trying with a 4GB stick ever since I bought my Roadster, and couldn't get anything to appear on the display -- it didn't seem to recognize the presence of the USB stick at all. Tried again with a 2 GB after reading this, and it worked like a charm.
     

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