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P85D Vbox guys -- anyone test to see if "Max Battery Power" changes anything?

Discussion in 'Model S' started by LetsGoFast, Oct 16, 2015.

  1. LetsGoFast

    LetsGoFast Active Member

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    I've read conflicting reports on P90D launches, has anyone with 7.0 tested the Max Battery thing? If not, consider this a call to action!
     
  2. kirkbauer

    kirkbauer Member

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    Can anybody explain what this max battery mode is and I use it?
     
  3. cynix

    cynix Member

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    Max Battery Power mode heats up your battery so that it can produce higher output in a short burst. However it causes battery degradation and will reduce the longevity of your battery, so Tesla advises that it should be used sparingly.
     
  4. ArtInCT

    ArtInCT Always Learning

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    Hi Cynix: That is some interesting information. Can you please post a link as to where you read this from Tesla Motors? If you are on shore power, does the heating energy come from the shore power or the main traction battery pack? I will be getting a P90DL and would like to be "up" on the guidelines and warnings.... and how that actually works... thanks.

    ARTinCT
     
  5. cynix

    cynix Member

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    Please see more information here: Max Battery Power setting in P90DL

    I'm still waiting for v7.0 for my P85D, so I don't really have any first-hand knowledge :)
     
  6. kirkbauer

    kirkbauer Member

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    i have 7.0 on my P85D and I'm pretty sure I haven't seen this option, I'll check again.
     
  7. LetsGoFast

    LetsGoFast Active Member

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    I do not believe that that the warning is intended to say that it will reduce battery life or cause degradation to the cells. I believe they are simply saying that you will consume electrons at a more rapid rate and that the battery will enter reduced power mode faster due to overheating more quickly.

    - - - Updated - - -

    I got it on 7.0 and tried it out, but my butt dyno didn't detect any performance difference.
     
  8. cynix

    cynix Member

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    Ah, that's good to know. Thanks for correcting my understanding.
     
  9. wk057

    wk057 Senior Tinkerer

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    I disagree. Heating the cells while they're at high states of charge definitely does cause accelerated degradation. This is a well known fact of the cell chemistry. Unless the pack is below a safe operating temperature I would never heat the cells.
     
  10. ArtInCT

    ArtInCT Always Learning

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    Do you think that perhaps the MAX POWER function may take into account the current pack operating temperature and know, based upon that data point, that it does not have to heat the pack? For instance if the pack environment system was cooling the pack down already? Your thoughts? Or am I expecting too much from Tesla engineering??
     
  11. AWDtsla

    AWDtsla Active Member

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    But how hot. If it's no worse than a summer's day, then it's no worse than driving your car in LA vs Montreal.
     
  12. wk057

    wk057 Senior Tinkerer

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    Based on other's posts it does seem to take the current temperature into account. I'm assuming max power is just a high pack thermostat set point.

    Don't know. Doesn't matter though. Hotter at high SoC = more degradation. So, a pack in LA will degrade more than a pack in Montreal, although Tesla's heating and cooling system should negate a lot of this under normal conditions. The max power heating function seems to go beyond this.
     
  13. techmaven

    techmaven Active Member

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    #14 techmaven, Oct 19, 2015
    Last edited: Oct 19, 2015
    Actually, Tesla/Panasonic's NCA chemistry is pretty tolerant of high temperatures... here's the research paper, examine the 2nd graph:

    Development of High Power and Long Life Lithium Secondary Batteries

    Note that the life cycle difference at 25 degrees C and 50 degrees C is roughly the same.
     
  14. Ldub22

    Ldub22 Member

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    @Techmaven wins the thread nerd award for linking to a paper that I can barely understand outside of cunjunctions and punctuation!

    ;-)
     
  15. wk057

    wk057 Senior Tinkerer

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    This paper has the same flaw that most battery related studies have. They simply charge and discharge repeatedly and think that's valid data. Unfortunately that's not how things work in the real world.

    Instead of charging to 100% and then immediately discharging at a high rate, we tend to stay at or near 100% longer and discharge more slowly.

    If you haven't watched this video, you probably should: Why do Li-ion Batteries die ? and how to improve the situation? - YouTube
     
  16. LetsGoFast

    LetsGoFast Active Member

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    Well, there are two different issues. One is what Tesla's statement actually says, which does not say that you will experience degradation. I'm pretty confident of that.

    The second issue is the question of whether or not Tesla allows the batteries to heat beyond a point where the cells will deteriorate and whether or not Tesla takes state of charge and other operating parameters into consideration. Although I certainly agree that it is possible to overheat the cells, we actually have no evidence to suggest that this is what takes place when you activate the function. In fact, we have very little evidence to suggest much of anything about its function. It is well-known that LiIon batteries perform poorly at lower temperatures and that damage occurs most often at high states of charge and high temperatures. There is a lot of room in the middle.
     
  17. Luclyluciano

    Luclyluciano Member

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    Ok but is the car faster or not?
     
  18. P85DEE

    P85DEE Active Member

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    Not.

    See post #2 in this thread.
     
  19. Andyw2100

    Andyw2100 Well-Known Member

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