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How does Tesla limit range in the SR?

Discussion in 'Model 3: Battery & Charging' started by djroberts, Jul 7, 2019.

  1. djroberts

    djroberts Member

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    The salesperson told me they just don't let you charge the batteries all the way by switching the software limit internally so that 90% actual equals 100% available.

    If that's the case, you could charge the SR to 100% and still maintain your battery as if you're only charging to 90%.

    Anyone know the answer to this?
     
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  2. OCR1

    OCR1 Active Member

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    Tesla has not released this information so we do not know if it is top locked or bottom locked. You will get a warning on the SR if you charge it to 220 miles (100%). Whether this is meaningful or not is not clear. I know a number of owners have asked this question to various Tesla personnel and nobody has posted a definitive answer on this forum.

    On the Model S that is software locked I believe we do know it is top locked and therefore safe to charge to 100% but I would not assume this to be the case on the Model 3 SR unless we hear it from someone credible.
     
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  3. ucmndd

    ucmndd Active Member

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    Yes, all software-locked Tesla batteries to date have behaved as you describe. You can safely charge the SR to 100% every day, which is about 92% actual SoC. The car will still bark at you every third or so charge warning you against charging to 100%, but that’s easy enough to dismiss.

    I did this for 40,000 miles on my Model S “60” before I purchased the upgrade to unlock it to a 75.
     
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  4. ucmndd

    ucmndd Active Member

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    Sure we do.

    Can you regen at “100%” on a Model 3 SR? Yes.

    Does supercharging slow to a trickle as you near “100%” on a Model 3 SR? No.

    Both indicators that there is obviously remaining capacity.
     
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  5. OCR1

    OCR1 Active Member

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    The Model S uses a different battery technology than the Model 3. This information is anecdotal and may be correct but I would not personally feel comfortable routinely charging to 100% unless I had a better understanding of the technical aspects of the software lock.
     
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  6. ucmndd

    ucmndd Active Member

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    There is nothing anecdotal about having regenerative braking available when the battery reads “100%”. That’s not physically possible on a battery actually at 100%.

    Nor is there anything anecdotal about supercharging in the tens of kilowatts when nearing “100%” charge, when batteries that are actually approaching 100% full supercharge at 1 or 2 kw.

    Even if Tesla came up with some super good reason to not use the code already present in their vehicle software that they’ve used to lock every other battery so far because the Model 3 has a “different battery technology”, they can’t change the characteristics of how batteries behave when they’re actually full.

    The idea of a bottom lock is silly, and doesn’t match confirmed history or observed reality.
     
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  7. Zoomit

    Zoomit Active Member

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    I haven’t seen any Supercharging reports from SR owners. Have you seen them on this forum? If not here, where?
     
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  8. ucmndd

    ucmndd Active Member

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    I swear I had but I'm not finding anything at the moment. That said, I'll eat my hat if it doesn't mirror the curve of the SR+ and finish up around ~15kw at "100%".
     
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  9. Zoomit

    Zoomit Active Member

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    Totally agree. I don’t think I’ve published my prediction for the SR charging curve, but it could still be at 24 kW when it hits 100% indicated SoC; 15kW will be more typical.
     
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  10. vickh

    vickh Active Member

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  11. albtrssp

    albtrssp Member

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    A bottom lock would be crazy. It would be really bad PR for a Tesla to artificially run out of charge in the middle of nowhere when it actually still had 10% left.
     
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  12. vickh

    vickh Active Member

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    Re: warning on the SR I did get one this week, but wrote it off since it's another programming flag they have to put in for the SR. Plus it would reward those who went cheap vs SR+

    Having range anxiety (as a new SR owner) I might continue doing it but my question is battery routine 100% considered abuse for warranty purposes?
     
  13. OCR1

    OCR1 Active Member

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    The warranty only guarantees 70% retention of the original full charge of the battery. So while there is nothing in the warranty excluding charging to 100%, it’s unlikely that doing so would cause the battery to degrade more than 30% in the first 8 years so you would most likely not have a valid claim.
     
  14. vickh

    vickh Active Member

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    fair enough. I don't want to intentionally harm the battery and claim, and I intend to trade in for the SR Y b/f the warranty expires. If 100% doesn't degrade battery, what other harm does it do?
     
  15. OCR1

    OCR1 Active Member

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    Theoretically someone looking to buy a used Model 3 could request that the seller charge the vehicle to 100% to see what range a full charge shows and compare it to the originally quoted range when the car was brand new, and draw some sort of conclusion about the battery health. But in practice I just don’t see people talking about doing this. So most likely any long term wear and tear you place on the battery by charging to 100% every day will only impact a future owner many years down the road.
     
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  16. pdx_m3s

    pdx_m3s Member

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    No one here knows for sure whether or not charging to 100% is equivalent to charging an SR+ to 90%. Someone posted screenshots of Tesla chat personnel saying it’s OK, but they have been wrong about so many things in the past.

    I’m in the small camp that believes the SR is bottom-locked rather than top locked.

    Only way to know for sure would be to measure battery pack voltage for similar age batteries at identical temperatures and charge percentage. If top-locked, the SR at 100% should read the same voltage as an SR+ at 90%.
     
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  17. ucmndd

    ucmndd Active Member

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    Super curious to know what has led you believe this despite all evidence, prior work, and common sense.

    Or, you know, check to see if the car has regenerative braking available and supercharges at a higher rate as the battery approaches “100%”.
     
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  18. ucmndd

    ucmndd Active Member

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    Your battery warranty is extremely straightforward. It’s warranted to retain 70% of its capacity in the first 8 years or 100k miles. Even if you charge it to 100% every single day. There is no exclusion for “abuse”.

    Very interested in hearing how your car behaves at 100%, particularly in regards to regenerative braking and supercharging.
     
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  19. ucmndd

    ucmndd Active Member

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    Not to mention all of the other negatives associated with it like battery degradation, slower charging at shared resources like superchargers, etc etc. There is literally no good reason for them to bottom lock the battery. Not one.
     
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  20. pdx_m3s

    pdx_m3s Member

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    From a future liability/warranty standpoint, bottom-locking a battery is more advantageous to Tesla, as it is easier on the cells: 99% of SR owners will follow the recommended daily charging guidelines and there is no risk to the cells being overly depleted (since the minimum they can get to is 10%). Remember, Tesla is going to extreme lengths to make the Model 3 profitable, even deleting panel clips; it would make perfect sense for them to reduce their battery liability by bottom-locking the battery.

    And the methods you mentioned are indirect ways to estimate charge limitation (top or bottom), but both are not fool-proof and can be interfered with via software. Measuring voltage is the direct means to determining charge limitation methodology.
     
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