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Pack Swap on 70D to 90kWh HP?

Discussion in 'Model S: Battery & Charging' started by bswn1, Feb 26, 2016.

  1. bswn1

    bswn1 Member

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    In the future, if a 70D was replaced with a 90kWh pack somehow would the HP output / speed then increase to that of a current 90D?
     
  2. Ingineer

    Ingineer Electrical Engineer

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    Yes. The D Motors are identical on non-P cars. The reason the 70D is lower performance is because the voltage of the 70kWh pack is lower due to it missing 2 of the 16 modules.
     
  3. bswn1

    bswn1 Member

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    Got it. Is this something that could be fixed with a software update in the future much like the 85D was or is it strictly a hard voltage limit? That may be a stupid question.
     
  4. Ingineer

    Ingineer Electrical Engineer

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    I think there is artificial performance limiting according to my back-of-the-napkin calculations. I bet a 70D could have more performance, but for marketing reasons, they limit it. Don't expect it to change. Tesla likes to "sweeten the pot" only on the high-margin models.
     
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  5. Muzzman1

    Muzzman1 Member

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    @Ingineer, you'd be the one to ask. Are the inverters in the 70's the same as the Non-P Dual cars? I suspect they are?
    Back when I had my classic 85, I kinda urked me that they were charging at the time $10k for a different inverter.
     
  6. wk057

    wk057 Senior Tinkerer

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    It's not even a different inverter.

    Based on my own analysis all of the small motors and inverters (70D, 85D, 90D, front of P85D/P90D) are all physically the same. All of the large motors and inverters (S40/S60/S85/P85/S90/rear of P85D and P90D) are all physically the same.

    The only differences are firmware, and relevant battery capability. An S85, for example, could be changed to P85 performance with just software. A 40 could be changed to P85 performance with a pack swap and software.
     
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  7. bswn1

    bswn1 Member

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    As a new soon to be owner who is still learning about the hardware of the cars, this is a bit unbelievable to me.

    If I'm understanding this correctly, it's not hard to imagine a future where larger 'refurbed' packs are offered at a specific cost which would upgrade not only the range, but the performance of the car.

    To confirm, the 70D -> 90D upgrade path would be as simple as a pack swap and firmware upgrade. Correct?
     
  8. wk057

    wk057 Senior Tinkerer

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    Correct. It's not really all that far fetched when you think about it. Makes a lot of sense from Tesla's perspective. Also makes a lot of sense for them to keep the perception that it's more complicated, even when it isn't.
     
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  9. bswn1

    bswn1 Member

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    Right. It makes no sense for them to offer this right now, but in the future when there's v2 and v3 of the body style and sensors, owners with older cars would likely pay for pack upgrades vs. new cars if that was an option. With the Gigafactory running at full capacity, a trade-in of your old pack in exchange for a reduced price on a full car upgrade sounds like a great program and revenue stream for them. Could push the current gen cars to 10 year life-cycles and beyond.
     
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  10. Muzzman1

    Muzzman1 Member

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    #10 Muzzman1, Feb 27, 2016
    Last edited: Feb 27, 2016
    Wow....my mind is Blown. I cannot believe the big motors are all physically the same. Wow. P85 & S85, the same (except the firmware). Mind completely blown. :eek:
     
  11. stopcrazypp

    stopcrazypp Well-Known Member

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    #11 stopcrazypp, Feb 27, 2016
    Last edited: Feb 27, 2016
    Wait, didn't Tesla already say before production release back in 2011 that the motors were the exactly same between the P85 and S85? The only difference was the inverter (P85 inverter can do 1200A and S85 can do 900A).
    http://www.teslamotorsclub.com/showthread.php/21625-Motor-battery-combo-performance-differences-S60-S85-and-P85/page2?p=444202&viewfull=1#post444202

    It is conceivable that they decided to make the inverters the same later on to reduce configuration differences (similar to how the 40kWh is a software limited 60kWh).

    It should be easy to tell from the part numbers.

    Edit (why didn't I think to look at the wiki? performance rear drive unit has a different part number):
    1002633-00-EASY,P-TRAIN,MECH,COMPLETE,RCStandard PowertrainBetween rear wheels
    1002633-01-EASY,P-TRAIN,SPORT,MECH,COMPLETEP85 PowertrainBetween rear wheels
    http://www.teslamotorsclub.com/showwiki.php?title=Model+S+Parts+List

    I remember someone mentioning that there is a longer lead time to get a replacement performance drive unit than a standard one. If they are physically the same (only software is different) that seems like a waste of time on Tesla's part (why not have same part number and upload software later).

    Front drive unit, I was aware previously was the same physically across all models (only the firmware is different).
     
  12. schonelucht

    schonelucht Active Member

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    The problem is that their upgrades are exciting enough that people are not just willing to buy a pack upgrade but buy a whole new car to get them. Unless that ever change there is zero incentive for Tesla to offer substantial upgrades like larger a larger pack. They have made vague promises from time to time about it and have changed maybe one or two packs but those were more of an accident than a real commercial strategy.
     
  13. wk057

    wk057 Senior Tinkerer

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    Part numbers are different. Motors and inverters still the same. It's smoke and mirrors... or rather stickers and fimware.

    I've personally been a part of and have driven a 60 (early VIN salvage repair) turned P85 with just a pack swap, configuration change, and firmware redeploy. Performance was P85 performance. Inverter temps normal, etc.
     
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  14. apacheguy

    apacheguy Sig 255, VIN 320

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    Hmm. Consensus is that the P has a souped up inverter. The DU otherwise is the same. Pretty sure it's listed differently in the parts catalog so seems there's more to it than software.

    Huh, that's surprising. Seems odd though that the part numbers are different.
     
  15. wk057

    wk057 Senior Tinkerer

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    Yeah, Tesla has definitely been pretty good at keeping this one under wraps. Even the service center people I've spoken with were unaware that they were the same motor/inverter, but a couple of techs conceded that it makes sense in hindsight.

    And really, it does make perfect sense. There's no advantage to them to have multiple hardware versions of basically the same thing when the cost difference/savings for doing so, on the hardware side, is virtually non-existent.
     
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  16. bswn1

    bswn1 Member

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    To wk057... in theory, could Tesla release a firmware update that makes the 70S / D faster than the current spec? Is there reason to believe the vehicle is limited by software vs. the battery / voltage output or are we currently at the limits of the car?
     
  17. stopcrazypp

    stopcrazypp Well-Known Member

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    That's interesting. So Tesla's own techs are wasting time ordering a performance drivetrain if that is true. I wonder however if there are any hardware differences inside (as in you can run the standard inverter at performance level, but it will degrade more quickly than one that is rated for that load, similar to how in a recent thread, transformers can be run above their load ratings).
     
  18. bswn1

    bswn1 Member

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    To expand on this, I've read the 85 kWh is really a 77 - 78 kWh usable battery. That's an effective 10% increase in usable battery with a 20% drop in 0-60 time delta between the 70D and 85D. Does that lend credence to the theory they're limiting the power of the 70s?
     
  19. wk057

    wk057 Senior Tinkerer

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    I'm 100% sure they could increase the power output to the motors with firmware on the 70D/60/S85/etc. I even think they still have some headroom with the 85D/90D. The 70/60's would certainly be amperage limited, however, and could never be made faster than their larger pack counterparts.

    I thought this at first too, which is why I was closely monitoring the temperatures reported by the drive unit of the 60->P85 I helped with. One thing in particular is that it reports temperatures on CAN for the bus bars for each AC output phase. I compared the temperature data to data from my wife's P85 (a real from Tesla P85) and there were no discernible differences in the data. This essentially proves that the relevant components are the same. If say, the AC output bus bars were smaller, they would heat up faster under full load. If the IGBTs were smaller, they would heat up faster, etc etc. The data showed that this wasn't the case.

    Further, I've seen the inside of a "standard" rear drive unit. There's nothing that suggests it couldn't handle the "performance" load.

    In short, yeah... Tesla is wasting their time partitioning the two. If there is some subtle difference between them besides the sticker and firmware then it doesn't appear to be related to functionality.

    - - - Updated - - -

    The data on that kind of speaks for itself. We know they're the same motors. We know the normal packs with the normal fuses can output about 1300A. The 70 packs are basically "85" packs with with 14 modules instead of 16 modules. So, exact capacity aside, it's capable of 87.5% of the power output of the "85" pack. I also have second-hand info confirming that the fuses in the 60/70 packs are the same.

    In short, yes I'm 100% sure the 70/70D is software limited.
     
  20. bswn1

    bswn1 Member

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    Very intersting and mind blown a bit.

    Do you have any thoughts as to WHY they're limited? Is it purely marketing (the 85D obviously has to be faster than the 70D, etc.), or is there some type of safety or longevity or other argument to be made here? Apologize if the answer is obvious, I'm still learning about the mechanics of the cars.
     

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