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Battery interior and Repair of Model S

Discussion in 'Model S: Battery & Charging' started by nir, May 31, 2014.

  1. nir

    nir Member

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    #1 nir, May 31, 2014
    Last edited: May 31, 2014
    This is the continuation of another thread - My P85 Salvage Story - Help!. I split it up because this related much more to the battery, and troubleshooting with pictures is below text.

    If you followed the thread above, you will know that i bought a Tesla p85 that was in a frontal (drivers-side) accident after 2 weeks. We discovered that the battery was hit in the corner. We repaired the bodywork of the car, and I now took the car to "Santa Monica Hybrid" . They specialize in electric and hybrid cars, and are the first in LA that specialize in hybrid and electric. Martin and his brother run the shop. They are very knowledgeable and professional with electrical batteries and have the correct equipment to diagnose and repair batteries.

    I brought him the car on Thursday, and by Friday, Martin had taken the battery out of the car and had diagnosed the problems. Here they are enumerated:

    1. I had tried unsuccessfully to charge the battery. It turns out that when Tesla received the car after the accident, they had disconnected the battery from the car, and covered the poles with plastic covers, and hid it back in the bumper - So it was NEVER going to charge (duh!) First problem solved.

    2. The front left corner was hit and impact raptured the coolant line in the first square (there are 12 compartments, with 2 battery packs in each - see pics).

    3. The bottom battery(they are stacked one top of the other) in that first square was also hit and some coolant affected.

    4. Martin tested all the other batteries, and the good news is that there is still some juice (20V) after 9 months of no charge, so my biggest concern of it being bricked, apparently is addressed.

    Martin believes that if we change the battery pack (which is tested as dead and repair the lines, then there is "99% chance" that battery will work.

    So the procedure at this point is:

    1. Source 1 battery within the pack, and replace it. Left and right packs are different. Alternatively find someone to repair that pack, but that apparently is more difficult. He has contacted Tesla to see if they will replace it (at cost). Since Martin is a professional with 22 years of experience, they might sell it to him. DC current is no joke and will kill you, so this is no Amateur work here. Please don't take this warning lightly - AC current will jolt you, DC Will grab and not let go.

    2. next step is to take each pack out of the car and charge/discharge 3x. It Takes 9 hours on a specialized machine, to bring all the batteries to the same level of charge. Martin believes that if you just plug it in and let it charge normally, that it might charge unequally, and affect he range. He checked all of the other battery packs and they all work.

    3. Repair the lines coolant lines - Thankfully because all the quadrant are separated, none of the coolant leaked onto the others. He checked them all.

    4. Once battery is charging we will deal with the software updates, and replacing the airbags.

    Thank you for reading... My apologies for the length of the email, but i wondered to be as thorough as possible.

    If any of you can source or know of any battery packs - salvaged or not please let me know. I will update as things develop. I would appreciate any feedback.

    20140530_124529.jpg 20140530_131236.jpg 20140530_131217.jpg 20140530_124804.jpg

    20140530_124752.jpg 20140530_124551.jpg 20140530_125331.jpg 20140530_125740.jpg
     

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  2. ThosEM

    ThosEM Space Weatherman

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    Thanks for the photos, and good luck with the process. It's good to know there are shops specializing in hybrids and electrics!
     
  3. MrIanB

    MrIanB Member

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    Why does that lt rear tire look more worn than the rt one??

    are the savings from salvage purchase worth what you may end up paying at the end to get the car running as if nothing ever happened??

    ian B
     
  4. dm33

    dm33 Member

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    400+ V DC will kill you just as well as AC. It is very deadly. Not sure where the DC vs. AC ideas come from.

    I think (but am not sure), that Tesla manages the battery charge at a much lower level than half a pack. It will try to balance the cells to maintain proper change. Not sure if its down to individual cells or a relatively small group of cells.
     
  5. Tharo

    Tharo Member

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    Very interesting.
     
  6. stopcrazypp

    stopcrazypp Well-Known Member

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    #6 stopcrazypp, May 31, 2014
    Last edited: May 31, 2014
    If you take a picture straight down on a left "pack" and right "pack" (since you say they are different) such that we can count the amount of cells, you can finally be able to help us solve the mystery of how many cells the Model S contains. If I'm not mistaken, there are 16 modules (or as you call them "packs") in the 85kWh pack. You show 14 in the flat section (1 damaged one taken out). There should also be two more stacked on top of each other near the front of the car.

    - - - Updated - - -

    Yes, it's a much smaller level. From looking at pictures of the battery diagnostic screens, Tesla manages it at 6 groups per module. Given 16 modules in total (for 85kWh pack) that's 96 groups of cells. One group would have all the cells wired in parallel so that they self balance (however each group must be balanced individually).
     
  7. yobigd20

    yobigd20 Well-Known Member

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    fascinating
     
  8. captain_zap

    captain_zap Electron tamer

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    I believe someone a while ago figured out there are 96 series groups of 74 cells in parallel in the 85 kWh pack. This has been deduced from photos of the diagnostic screen, pics of battery pack guts, observed min/max charging voltages, and also seems to work out in a spreadsheet using known min/max voltages of the cells. So that's 7104 cells.
     
  9. nir

    nir Member

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    20140530_131225.jpg
    I think this is the pic that you asked for. There are in fact 16 "modules" (thank you for correcting my nomenclature). you will see 7 right, 7 left, and 2 center ones.
     
  10. stopcrazypp

    stopcrazypp Well-Known Member

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    #10 stopcrazypp, May 31, 2014
    Last edited: May 31, 2014
    The number of cells in a parallel group were never verified. The closest we got was when the NHTSA posted pictures of the pack opened up, but they were too blurry to get a clear count of the cells.
    http://www.teslamotorsclub.com/showthread.php/21850-NHTSA-Opened-Up-the-Model-S-Battery-Pack-Pics

    We are pretty sure about the 96 series group number (this can be figured out from many sources), but the 74 number can't be figured out simply by math or other indirect means (only by counting the actual cells in the pack, which this is a perfect chance to do).
     
  11. nir

    nir Member

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    Why does that lt rear tire look more worn than the rt one??

    are the savings from salvage purchase worth what you may end up paying at the end to get the car running as if nothing ever happened??

    ian B


    Ian, It is just the picture. they are both the same tread. I can not answer whether this will be economically sound. My guess would be probably no. I did not do it for the $ only. Journey vs destination argument. I do know however that i am much more confident about the car now, and its brand new tech, because i understand first hand all the failsafes that have been put in place, and i certainly have learned a lot, albeit at my cost.
     
  12. stopcrazypp

    stopcrazypp Well-Known Member

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    Thanks for verifying there are 16 "modules". Actually the picture needed would be a straight top down of at least one of the modules. Similar to this one, except from a top down perspective and showing the whole module (so that it's possible to count the number of cells in a module):
    This would be further complicated if what you mean is that the modules on the left and on the right side are different (and have different number of cells per module). That means we would need a picture of one of the "left" modules, and one of the "right" modules.
     
  13. nir

    nir Member

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    This is the best one i have. I will take others when i go back there next week. TO be clear the number of cells should be the same. it is just that the connectors are in the opposite directions. 20140530_131221.jpg
     
  14. stopcrazypp

    stopcrazypp Well-Known Member

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    #14 stopcrazypp, May 31, 2014
    Last edited: May 31, 2014
    This one is perfect. I would imagine the number of cells should be the same too.

    Edit: I just counted this one. It seems to be 444 cells, which if we break into 6 groups would be 74 cells per group (verifying the guess from before). Total cell count would be 444*16 modules = 7104 total cells, which matches the best guess we have had so far.
     
  15. MrIanB

    MrIanB Member

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    Ok, ok, it only has to make sense to you. Wish you luck and hope u r able to get it running and pass inspection.

    ian B
     
  16. SCW-Greg

    SCW-Greg Active Member

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    Yep, good count.
    Interesting in how they're grouped in this picture, with the different break lines.
     
  17. Electricfan

    Electricfan Member

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    Thanks for posting about your restoration project. Hoping you're driving with the Tesla grin very soon. Please post more pics and info about how it goes. Maybe there are more "totaled" Model S.s out there that can be salvaged with lessons learned by you and your mechanic. Hope you spread the word. Maybe the shop doing this work can offer this in the future as a specialty. I want to "upgrade" to a performance model - maybe this is something that could be done by specialty shops someday. I wish Tesla had made this kind of upgrade easy. Seems like they could have designed the car so that it was "upgradeable". Why isn't swapping out an electric motor and inverter and gearbox easier than replacing an ICE?
     
  18. swegman

    swegman Member

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    It is easier. Its just priced expensively to discourage people from doing it.
     
  19. invisik

    invisik Member

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    Do you think you could rewire to bypass that damaged module?

    -m
     
  20. stopcrazypp

    stopcrazypp Well-Known Member

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    #20 stopcrazypp, Jun 1, 2014
    Last edited: Jun 1, 2014
    One module is responsible for 6.25% of the voltage of the pack (as it's responsible for 6 groups wired in series out of a total of 96 groups). So a simple bypass will not work without tweaking the firmware to simulate a 60kWh pack, which has a lower pack voltage from using two less modules than the 85kWh version. This will also affect the performance of the car (from lower pack voltage).

    One option is to rewire the other modules to make up the difference (for example, rewire 6 modules to have 7 series groups instead of 6), but then those modules will tend to get out of balance relative to the others, and it might also limit your total capacity (because of how balancing works). And the performance problem will also pop up (the 6 rewired modules might be over-stressed).

    It's far simpler to just repair the damaged module or find a replacement module.
     

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