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Losing maximum power in Roadster Sport - due to battery aging?

Discussion in 'Roadster: Performance' started by Marius, Nov 29, 2015.

  1. Marius

    Marius Member

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    Last few months I detect that I do not get maximum power at full throttle. In white performance mode the kW meter originally reached 200kW and is now reaching not more than 150 kW.
    The roadster is 6 years old. CAC 132, mileage at 240.000 km
    First I expected this reduction caused by dirt, since my last service was 1 year ago. However after service last week, kW power did not improve.
    Do other Roadster owners experience also a power loss probably caused by aging of the battery pack?
    Or is there another cause for this?
     
  2. Chickenlittle

    Chickenlittle Active Member

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    Title assumes loss secondary to aging yet you ask in the text whether its aging
     
  3. ecarfan

    ecarfan Well-Known Member

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    Loosing maximum power due to aging of batterie of Roadster Sport

    There probably aren't too many Roadster owners with anywhere near 240,000 kilometers (almost 140,000 miles) but we know the data shows that battery degradation is highly correlated with mileage, and your low CAC bears that out.
    As to whether or not that is the explanation for your power loss, I can't say for sure but it certainly seems likely.
    The way I read the OP's question, he's asking if his loss of max power is due to the battery degradation. Please note he is not a native English speaker.
    @Marius, it sounds like it is time for your Roadster to get a new 3.0 battery! [emoji3]
     
  4. djp

    djp Roadster 2.0 VIN939

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    Yes, the max power will fall as the battery ages. Over time the internal resistance of the battery increases which means you'll see more voltage sag on hard acceleration and less power. That might not explain the full loss though, there could still be other causes as well.
     
  5. apacheguy

    apacheguy Sig 255, VIN 320

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    A reduction of 25% seems too great to be caused by battery degradation alone in only 140,000 miles. What is your CAC compared to a new value?
     
  6. ecarfan

    ecarfan Well-Known Member

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    Loosing maximum power due to aging of batterie of Roadster Sport

    He posted that his CAC is 132. That is well below a new CAC of over 160 (can't recall exactly what the value is). The Plug In America battery survey shows declines in battery capacity with increasing mileage. His mileage is pretty high.
     
  7. Marius

    Marius Member

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    Beside the apparent loss of max power my Roadster is performing well.
    Anyway I want to raise the question since I read a lot of owners suspend replacement of the battery since a range loss of 15% is acceptable. However it seems that aging also brings performance loss.
    I can understand the mechanism as drawing high current from an old battery makes a bigger drop in voltage hence drop in power (kW being amp* volt)
    There are a lot more roadster drivers with a CAC of the same value as mine so it can be interesting to know if what I think is experienced by others also.
     
  8. Doug_G

    Doug_G Lead Moderator

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    Mod Note: Edited the title to clarify the topic under discussion.
     
  9. MLAUTO

    MLAUTO Member

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    Set the charge mode to performance and fully charge the battery, then see if the acceleration improves. There is a noticeable increase in performance between a standard charge and a performance charge. That will let you know for sure if it is a battery issue or something else.
     
  10. Marius

    Marius Member

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    Thanks Doug, I forgot the question mark.
     
  11. stopcrazypp

    stopcrazypp Well-Known Member

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    25% reduction seems to be a bit much just for resistance growth due to aging. If I have the time I can probably do an estimate of resistance growth effects.

    I agree with others. Try to replicate the same conditions as the original test. This includes not only battery SOC, but also air temperature.

    When you went into service, that perhaps should have been the best time to ask. They could have looked at the car more thoroughly to see if anything is limiting power.
     
  12. apacheguy

    apacheguy Sig 255, VIN 320

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    @crazypp - I would be interested to see what you could put together as far as resistance growth and performance decline.
     
  13. Juanmax

    Juanmax Member

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    Battery temp plays also a big role in power delivery. Chemical reactions happen slower if the components are cold. That is the reason why in performance mode, the battery is allowed to get hotter before cooling it down. (you get more power out, but degradation happens quicker)

    Mine has 144.000km and a CAC value of 143 and still delivers 200kW.
     
  14. MLAUTO

    MLAUTO Member

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    By the time you use the battery enough to get it warm, the advantages of the extra voltage from a performance charge are long gone. You would have to start with a warm battery and then do a performance charge. One of my roadsters is used strictly for autocross, and the battery temps hardly move. Even after going thru 1/3 of its charge in 90'+ air temps. The cooling temp for performance mode is only 3'C higher, so I'm not sure how much of a difference that would make.
     
  15. supersnoop

    supersnoop Tesla Roadster #334

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    I thought the entire purpose of "Performance Mode" allowing the battery to reach higher temperatures was to delay the cooling system from drawing power so frequently. You don't get any gain from the battery being warmer; you gain because power isn't going to the cooling system.
     
  16. apacheguy

    apacheguy Sig 255, VIN 320

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    Warmer cells have less resistance so there definitely is a benefit aside from freeing up cooling resources.
     
  17. bolosky

    bolosky Member

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    I've noticed getting 150kW lately, but I'm pretty sure that it's because the weather has been really cold and the battery is something like 8C. By the end of the day driving when the battery gets up to more like 20C I get full power, unless it's at low SOC, in which case the power is also reduced. I'm around 96K miles.

    Also, doesn't charging in performance mode actually heat the battery (using the battery heater in addition to thermal loss from charging)?
     
  18. apacheguy

    apacheguy Sig 255, VIN 320

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    It's been pointed out the perf mode on the Roadster only raises the target by 3 C so not much different.
     
  19. wiztecy

    wiztecy Active Member

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    #19 wiztecy, Dec 4, 2015
    Last edited: Dec 4, 2015
    A good benchmark for other' to compare to or use for future reference is the torque/HP screen that's in the VDS. From a dead stop and a full std. mode charge punch it and see what the values read. From there we can compare the values against others with varying CAC to draw a statistical conclusion. I already know that a lower CAC will not yield as much power, but its great for others as a reference as I mentioned.

    If you do that please post the pic. Also note what temp of the ESS is at as well as the SOC or ideal miles.

    Also when you stomp on the accelerator, what's the max reading of amps the dash reads? You might be able to calculate against say a pack that has a CAC in the 150's with yours that's in the 130's. Just another data point.
     
  20. Marius

    Marius Member

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    I have done all that is advised in this threat. Performance charging and making sure of a warm battery and so on. Still in performance mode I do not get more than about 180 kW which used to be a full 200 kW.
    I still blame it on the age and degradation of the pack.
    Are there any owners with a CAC similar or lower than 130 who can proof otherwise?
    I know on the TFF forum in Germany there is someone known as Talkredius who did more miles than me and reached a CAC of 109.
     

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