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Minimum ambient air temp to avoid regen limitations of a cold battery

Discussion in 'Model S: Battery & Charging' started by autodidaddict, Nov 12, 2015.

  1. autodidaddict

    autodidaddict Member

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    Greetings. I went looking for this information because I could've sworn I had seen it elsewhere before, so apologies to the moderators if this has been asked and answered. Today I noticed that after the Tesla sits for a decent amount of time (raining, 50F air temp), when I get in the car the yellow "regen limited" line is showing on the gauge in the dash. After a few minutes of highway driving, this goes away.

    I was wondering what the minimum air temperature is to avoid the "regen limited" light. Also - since my trip would have been mostly highway anyway, should I even be concerned about this limitation since I wouldn't have used much regen at all? And, would preheating the cabin with range mode off have made a big difference in power consumption with the air temp being a relatively mild 50F? I can totally see the desire to do this had the car been sitting cold in like 10 or 20 degrees F, but is it really worth doing anything at 50F?
     
  2. gimmi80

    gimmi80 Member

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    From what I understand the heating of the cabin is separate from the heating of the battery.
    If the battery gets cold regen is limited. The battery has a heating/cooling system but is regulated automatically and can not be activated by the user. If the car is plugged in to a 220v connection heating/cooling of the battery is more aggressive then if you are unplugged or plugged to a 110v.
    You can pre-heat the cabin but that will not have effect on regen, you will still get in the car and find the yellow dotted line.

    Some speculated that keeping the car in range mode, has an effect on the self activation of heating/cooling of the battery extending the window of activation in order to save battery power. Someone in a previous post also alluded to the fact that this could have a negative impact on battery life, however I seems to be a mere speculation.

    If you are plugged in preheating the cabin is definitely economical (on battery power) if you are not plugged in I think it does not have any effect on total energy used for your trip, as anyway you are going to heat the cabin while driving, so sooner or later you use that battery power anyway.
     
  3. Max*

    Max* Autopilot != Autonomous

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    My non scientific observations put it around 60F
     
  4. 5thumbs

    5thumbs Member

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    Are we talking about a yellow triangle with and exclamation point on it, at the bottom right of the energy diagram on the dash? I have been seeing this when I get in the car and hear a beeping. I could not figure out what it was. I live in CA and in my garage it does not get much below 55.
     
  5. Andyw2100

    Andyw2100 Well-Known Member

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    A lot of the above is wrong.

    There are many posts on this, from well-respected posters like jerry33.

    With range mode off, preheating the cabin will heat the battery pack as well. Depending on the temperature, it may not heat it enough to completely eliminate the regen limit. With range mode on, heating the cabin does not heat the pack.

    When you begin driving, with range mode on, no extra energy is used to heat the pack, and if you have a regen limit it will take some time before it goes away. With range mode off, energy usage will be higher, as the pack will be being heated, and the regen limit will go away sooner.

    One very effective way to minimize the regen limit is to time your charge such that it ends just before you are going to start driving. The pack has to be heated in order to charge. Again, depending on your climate, this may not eliminate all of the regen limit.

    Many of us have been hoping for a separate battery heating option. Here are two related threads:

    Suggestion for battery pre-heating and charge-end scheduling sent to Tesla

    Would you use battery heating if it were available?
     
  6. autodidaddict

    autodidaddict Member

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    @Andyw2100 this is what I was looking for. I've been reading the other threads about separate battery heating controls, etc. and this is what made me curious as to what the temperature is that typically triggers the cold battery regen limiter. When I'm at home, and I know what I'm going to do the next day, I can definitely try and time the charging so it finishes just before I leave, keeping the battery warm.

    But, when I'm out in a parking lot and not plugged into anything, I think I'll preheat based more on driver comfort rather than trying to predict what level of heating will drop my regen limit.

    Thanks!
     
  7. mknox

    mknox Well-Known Member

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    I feel this has changed with recent versions of 6.x and 7. I am heading into my third winter with the car and do not recall seeing re-gen limits in the past until I was very close to the freezing point. I too am seeing the re-gen limit when temps are in the 50's and often higher:

    IMG_0532.JPG
     
  8. Andyw2100

    Andyw2100 Well-Known Member

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    Happy to help!

    Another reason we need battery pre-heating is so that people can choose to never drive with a regen limit if they prefer to do that. Some people may prefer to not have to adjust how they slow down, based on whether or not their regen is currently limited, and based on what that limit currently is. They may prefer to use a little more energy--either shore power or even battery power before starting the drive--to eliminate the regen limit entirely. There's no reason Tesla can't provide this option. Tesla has now provided the option to heat the pack to a higher temperature, just to get an extra couple of tenths of a second of performance out of the cars with the Max Battery Power option. They should also provide the option to heat the pack for more typical every-day use.
     
  9. Oba

    Oba Member

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    I concur... 15C for the battery temperature.
     
  10. gimmi80

    gimmi80 Member

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    THanks for the correction. I'm happy to learn how the system really works.
     
  11. Andyw2100

    Andyw2100 Well-Known Member

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    No problem!

    Interestingly just last night I started a thread because I think there is a chance there has been a change in version 7 of the firmware, but I'm not certain. That thread is here:

    Possible Change to Battery Heating / Range Mode in Version 7
     
  12. cinergi

    cinergi Active Member

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    It's around 60F as noted. It won't show on the energy mini app until close to 55 tho. You can have some regen limit without it showing. This has been true the last 3 years I've owned the Model S.
     

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