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Battery is big disappointment

Discussion in 'Model 3: Battery & Charging' started by azred, Jul 28, 2017.

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  1. Cloxxki

    Cloxxki Active Member

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    What snippets of info are you basing this on? The official curb weight difference between SR and LR is 120kg. Looks like extra modules to me. Say, 5 modules of ~10.5kWh for the SR, 8 modules for the LR. Possiby one with fewer cells, or simply some extra capacity to play with on the LR pack which is so well paid (~$400/kWh for the upgrade alone, 3-4x cost).
    SR could also be 6 modules each with a few cells less than fits, LR 8 very full modules of ~9.5kWh each.
     
  2. Trancela

    Trancela Member

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    Internal cell resistance is nominally 100 mOhm. So at 4.3C, each cell generates a whopping 21 W of heat. Now imagine a few of the 8,000 cells are at 200 mOhm due to manufacturing variances. So now you have a cell generating 42 W of thermal energy. In no time will the thing reach 100 to 150 degrees and destroy the cell if not cause it to ignite/short.

    For the Ludicrous, the rate is 5.8C. So that will generate 78 W and soon the thing would be glowing! They better use a different chemistry and hand select the cells so they have the least internal resistance.
     
    • Like x 1
  3. ShockOnT

    ShockOnT ⚡️⚡️⚡️⚡️⚡️

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    Wait for the dual :)
     
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  4. Cloxxki

    Cloxxki Active Member

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    From acceleration power graphs we know that the 5.8C is gone is pretty much exactly a blink of the eye. It takes a while in racing type situation to dip below 2C though.
     
  5. Trancela

    Trancela Member

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    #105 Trancela, Jul 29, 2017
    Last edited: Jul 29, 2017
    Modules have a fixed voltage, and I doubt that Tesla would make two different modules, one for the SR and one for the LR. Thus if they don't have the same number of modules, the voltages will be different which impacts all the electronics and motors, software, etc. I believe Tesla like with most other manufacturers have standardized on 96 serial cells which is either 6 x 16 or 8 x 12. So the architecture is either 6M16S43P or 8M12S43P. Thus it is not possible to change the number of modules within the same model as that would be too costly. What they can do is make the module have less energy capacity for the SR, by using cells of lesser capacity (or fewer actual cells in parallel). Thus both T3 are let's say 6M16S43P, but the SR uses 3.4 Ah cells (either the model S 18650 fit in a 2170 can, or a low-capacity 2170) while the LR uses standard 2170 at 4.9 Ah. This way the battery pack is identical -- same number of modules, same module sizes, same number of serial and parallel cells, same voltages. This streamlines the production as there is only one drive train for both vehicles. The difference is which cell they choose to put into the module and some minor software adjustments.

    And in the future they could even put the same cells, but software cripple the drive train from 310 miles to 265 miles or 215 miles, and charge a premium for uncrippling.
     
  6. Trancela

    Trancela Member

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    Yes, I suspect the reason the 100L seems to fall back towards the end of the race is because of software throttling as the cells have reached their thermal limit.

    This issue will probably go away when we get a 150L, where 3.9C will have the same effect as 5.8C (minus the extra battery weight). Or if they use a high-power (resulting in low energy) chemistry.
     
  7. R.S

    R.S Active Member

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    It's the motors. An induction motor starts to loose power after a certain RPM. In the case of a P100D, the motor power starts dropping after 100mph. If it had two gears per motor, it could be quicker above 100mph.
     
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  8. Cloxxki

    Cloxxki Active Member

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    Both stator and cells heat up from the moment a L session gets underway. I doubt that would a better cooled or large motor, the cells would hang on to 5.8C for much longer. Seconds at most. And perhaps theycould, but Tesla doesn't let the management system waitt for critical temperatures, throttles output before it gets there so the fall-offf is not as abrupt. Also, 5.8C can't be great for the cells. Even with cooling twice as effective, pulling the cells that hard can't be good. Not when there'a great warranty policy on the pack. Which seems to change for Model 3.
     
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  9. R.S

    R.S Active Member

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    I din't mention heat, it's just the basic working principal of an induction motor.
     
  10. Farmer

    Farmer Member

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    #110 Farmer, Jul 29, 2017
    Last edited: Jul 29, 2017
    I see you're in Maine. The speed limit on 95 north of Old Town is 75 all the way to Houlton, from mile 193 to mile 304. 'Just saying... :)
     
  11. kort677

    kort677 Banned

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    if you require more range than what is offered in the model 3 then maybe you should consider a car with a range that meets your needs
     
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  12. jelloslug

    jelloslug Active Member

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    Its not even noticeable on my Model S.
     
  13. jelloslug

    jelloslug Active Member

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    Exactly, there are lots and lots of people here with Model 3 reservations that don't currently have EVs and still have that "OMG, I need 300 miles of range for my two long trips a year I take".
     
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  14. scaesare

    scaesare Well-Known Member

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    I don't believe we know that (or anything else) about the new cells yet.
     
  15. scaesare

    scaesare Well-Known Member

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    Doing this is not practical.
     
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  16. scaesare

    scaesare Well-Known Member

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    Read what he wrote. He's not talking some abstract notion based on a spec sheet of a cell that's not necessarily the same as the ones in the car. He's telling you what the car does in practice.
     
    • Disagree x 1
  17. kort677

    kort677 Banned

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    I don't know where you are from but in a good part of the US the speed limits on interstate like highways is posted at 70 mph and in a few places the limit is higher, most people drive the speed limit + a few miles over so I think that you comment 75 mph isn't a normal speed is misinformed.
    fwiw I've taken many long distance trips and on good weather days on roads without long upgrades I've found that driving my s90d at between 70-75 MPH is a good balance between speed and efficiency.
    YMMV
     
  18. ahaer

    ahaer Member

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    I'm not thrilled by the price difference either. 90 miles for $9000 would make the price (not cost) of the base battery $22,000. Which means the price of everything else is only $13,000... This is like Apple charging $100 to go from 32G to 64g when a 64G chip only costs $5 more...

    It especially annoying when the major difference in the battery pack is that they just have more of the same battery cells, probably even in the same case. It would be different if they had to use "more expensive" cells to achieve greater range instead of just more of the same cell.

    There could be some additional upgrades to motor/controller as well that are part of the improved performance of the longer range. My guess is that Tesla wouldn't make two different motor/controllers for simplicity in production and the additional performance is solely the result of more current available from the larger pack.

    Also they are marketing this as a range feature ("standard" vs "long range") not a performance option
     
  19. Candleflame

    Candleflame Active Member

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    In europe the police would probably pull you ever for going 55mph on a motorway. lol Even lorrys go faster than that.
     
  20. ProtomanX

    ProtomanX Member

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    $9000 did seems a lot at first, but when you look at the Model S, it cost roughly $20k to go from 259 to 335 miles. It is not really that bad plus with tripling supercharge by next year, road trip with base some be more viable.
     

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