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Internal battery questions?

Discussion in 'Roadster: Technical' started by chris22104, Mar 8, 2012.

  1. chris22104

    chris22104 Member

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    Has anyone ever opened up a battery pack to work on it? From what I've read, the cells are in sheets, correct? If so, how many sheets, and how many cells in a sheet? What does a "brick" of cells refer to then? Any pics out there? Anyone work on a pack themselves? Having a lot of experience in smaller versions of ni-cad and ni-mh packs in series, I'm quite curious....Nobody else makes replacement sheets for the roadster, right? Are the individual cells available?
     
  2. rabar10

    rabar10 FFE until Model 3

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    Roadster Technology - Battery

     
  3. dsm363

    dsm363 Roadster + Sig Model S

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    You void your warranty if you mess with your battery pack so I'd imagine too many people haven't done it. The link above is a good article though.
     
  4. dhrivnak

    dhrivnak Active Member

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    It also weighs 1000 lbs and has to be removed from the underside while on a lift. No easy task.
     
  5. roblab

    roblab Active Member

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    Sixty nine cells per brick, but only NINE bricks per sheet, 11 sheets, makes 6831.

    I thought my math was goofy for a second. OK, it's goofy, but I can at least do add and subtract. Had me worried.
     
  6. chris22104

    chris22104 Member

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    Anyone out of warranty pay to have their pack tested/serviced? What needed to be done, and what was the cost?
     
  7. The_User

    The_User Member

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    I agree, not that I would ever venture to remove a 1,000lb battery to begin with....each sheet will be close to 100lbs alone continuing to make the battery hard to service unless you really had all the correct equipment. Damaging the casing or sheets would be my largest concern. In pictures I've seen and at the local dealership, they have special holders and lifts to remove, install and work on the battery packs. I had the batteries leak tested in a 2009 Roadster last month. It was still under warranty (free).
     
  8. Bearman

    Bearman Member

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  9. Doug_G

    Doug_G Lead Moderator

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    From what I've heard, removing/installing the battery is a very time-consuming and quite difficult job even with the proper equipment.
     
  10. hcsharp

    hcsharp Active Member

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    Yeah. It was enough to make me decide to buy the battery replacement program. Something like 12 person-hrs to swap a battery. You have to remove pretty much the entire drive train.
     
  11. Installing and removing the battery is not nearly as difficult as trying to open up the casing of the battery, replacing the cells and then trying to make it all work.

    I think most any competent shop could probably remove and install the battery, it would be far more difficult to open up the casing replace sheets/bricks/cells, put it all back together and still have a working vehicle.
     
  12. Mookuh

    Mookuh Member

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    A few questions for Roadster owners (I hope this thread is appropriate enough):

    The battery loses charge over time when not plugged in, *relatively* quickly so when coming from a full charge.
    Does the Roadster actually draw power to make up for this loss when plugged in, or is keeping it connected enough to prevent power loss by applying voltage?
    Is the discharge coming only from the monitoring/cooling systems or is it electrons "sneaking their way around the battery"?
    How much power does the Roadster draw when connected but fully charged in a day/a week?
     
  13. dhrivnak

    dhrivnak Active Member

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    As for replacing the battery one of the larger challenges is you pull it from the bottom of the car and at 975lbs it is quite heavy and normal lifts for engines will not work.

    As for the battery discharging you lose one ideal mile a day so it would take 180 days or a half year to discharge. If you keep it plugged in then yes it will wake up about once a day and top off using about .25KWH per day.
     
  14. Dragon

    Dragon Lightning Green Fairytale

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    The discharging rate drops faster with a high state of charge, it's not constant. My car consumes 0.4 KWH per day.
     
  15. Alfred

    Alfred Member

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    The Roadster will check once every 24 h if it has to add some charge to reach again its "Standard"- level, corresponding to a charge to about 85%. I have set the roadster to charge at 3 a.m. The loss between the end of a recharge then and 3 p.m. is not quantifiable with any accuracy. The sources of losses are diverse. I would expect that the largest losses are due to self discharge. I have not checked whether there is a steady load also between the charging cycles mentioned. The manual says: "When plugged in, the vehicle optimises the lifetime of the Battery by managing its charge level and temperature. The vehicle wakes up every 24 hours and, if needed, automatically initiates the charging process to keep the Battery at an optimum charge level."
     
  16. Doug_G

    Doug_G Lead Moderator

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    From what I have seen, if you put the car in storage mode, the battery depletes about 0.5% a day. I believe most of that is due to the control processors, which are constantly running to monitor battery state and safety.

    The exception is extremely hot conditions, when the battery requires active cooling to preserve its lifetime. In that case the drain can be much larger.

    In Normal mode the car tops up once a day. In Storage mode it wakes up once a day to see if anything needs to be done, then immediately shuts down - unless the battery is very low in which case it tops up a bit.
     
  17. Mookuh

    Mookuh Member

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    Thank you for the responses.
    I remember seeing a thread in the Model S section about the "Model S battery impossible to 'brick'", but I seem to be unable to find it right now. It did mention a non-linear discharge of the Roadster battery when stationary, which implied it being the Battery discharging itself and not the monitoring systems sucking up the power.
    Money wise, the static discharge of 0.25 Wh/d to 0.4 Wh/d are a non issue.
     

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