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Battery Heating May Have Changed

Discussion in 'Model S: Battery & Charging' started by Andyw2100, Jan 31, 2017.

  1. Andyw2100

    Andyw2100 Supporting Member

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    It has long been the common belief here on TMC that if one preheated the cabin, while on shore power, with range mode off, the battery pack would also be heated, provided the pack was cold. (if the pack had been charging, it may not have been cold.)

    I think there is a chance that this behavior has recently changed. I am saying that because of some posts in another thread. Here is one of the relevant posts:

    TeslaFi.com

    Basically using TeslaFi, we can see when our battery heater is on. And it appears it may not be turning on when preheating the cabin.

    Additionally, it seems that the battery heater may not come on 100% of the time the battery is cold and a drive is started with range mode off. The common belief here had always been that the battery heater DID come on in this situation, which was one of the reasons wh/mi numbers are quite high during short, cold drives.

    It would be great if others with the ability to monitor the battery heater weighed in on this.

    Thanks!
     
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  2. Cyclone

    Cyclone Cyclonic Member ((.oO))

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    My battery is currently somewhat cold, exhibiting regen limited to 30 kW when I moved it between garage stalls a few minutes ago. What testing would you like?

    Meanwhile, I'll go through some of my driving history via TeslaFi. I know I saw some entries with battery heater on, but I don't recall the details.
     
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  3. Andyw2100

    Andyw2100 Supporting Member

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    With range mode off, and plugged in, if you started cabin heating now the old theory was that the battery heater would come on. So if you tried that, and then looked at the TeslaFi data to see whether or not the battery heater came on or not, that would be helpful.

    If you wanted to take it a step further, you could go for a short drive, after preheating the cabin a bit, and see if the battery heater came on during the drive. Obviously I'm not going to ask you to go for a drive, though, just to test this. You could do the same test the next time the battery is cold, and you're going for a drive anyway.

    Thanks for being willing to help!
     
  4. apacheguy

    apacheguy S Sig #255

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    The pack heater should come on, but only until it reaches the target of 8 C.
     
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  5. Andyw2100

    Andyw2100 Supporting Member

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    Thanks.

    Is that true for the cabin pre-heating only, or for both cabin pre-heating and driving? Also, as far as you know, has this number--8 C, or 46.4 F--changed at all recently?

    Finally, do you know at what battery temperature there would be no regen limit? Do you know if this has changed? (My gut feeling is that about a year ago, give or take, the regen limit started kicking in at higher temperatures than previously, meaning the battery needed to be even warmer to not have any regen limit at all.)

    Thanks again!
     
  6. Hugh Mannity

    Hugh Mannity Mediocre Member

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    By looking at teslaFI how do you know the batt heater is in? I don't see that info in the raw data.
     
  7. Andyw2100

    Andyw2100 Supporting Member

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    After I exported the data the "battery heater on" column was column W.
     
  8. Hugh Mannity

    Hugh Mannity Mediocre Member

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    Oh I've never exported. Thanks! Will try thay
     
  9. Andyw2100

    Andyw2100 Supporting Member

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    You mentioned "raw data" so I thought that is what you meant.

    You can see the battery heater status within TeslaFi too. You can "edit" the layout, and there are two blank fields. You can select the "battery heater on" criteria in the drop down.

    Good luck.
     
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  10. ThisIsTrue

    ThisIsTrue Dismember

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    My garage is always >46.4 F. The way I warm the car up before going out in the cold is to kick up the charge limit 30-60 minutes before I leave, under the theory that charging warms the battery. So far, I've NEVER seen limited regen, though I only have about 6000 miles on the car so far. (Cut me some slack: I've only had it for 6 weeks!)
     
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  11. apacheguy

    apacheguy S Sig #255

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    It is certainly possible that the newer firmware have changed the heating target. But AFAIK when the pack is online and providing any kind of energy the thermal limits are enforced by the thermal controller.
     
  12. ev-now

    ev-now Member

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    Slacker ,,,
     
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  13. crash90D

    crash90D New Member

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    I'm in Canada, it's currently about -10DegC (14DegF) and my battery was stone cold. I haven't completed the TeslaFi Login, but cabin preheating does to a job of warming up the battery .. to a certain extent. In the colder than -20DegC (-4DegF) we have about 2 weeks back, the batter just got to warm (no dotted orange bars) after 30 minutes of cabin warming AND 35km of driving. I'm looking forward to 8.1 ..

    That said, the rest of the heating and defrosting system has been brilliant this winter.
     
  14. bjornb

    bjornb Member

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    I've taken a look at other fields as well from this morning when I did a preheat which is of interest:
    battery_current, charger_current and charger_voltage.
    Before starting preheating battery current was at -0.3A (a load of 100W+ or so since I use the always connected setting in my car).

    When I started heating battery_heater_on remained false, but I can see current flowing from both the wall and the battery.
    Iit did at one point pull 14.7 amps from the battery and 12A (at 229V) from the wall. If we assume a conservative (?) pack voltage of 390V (SOC at 80%) that gives us a power consumtion in the car at: 14.7A x 390V + 12A x 229V = 5733W + 2748W = 8481W total power

    Shouldn't this mean that both battery and cabin heating is active? I have read elsewhere on this forum that the car has 6kW cabin heater and 5.5kW battery heater, and since total consumed power is more than the cabin heater is able to consume alone I assume the power is distributed between pack and cabin heating?

    How much total power do your cars consume when preheating in cold temperatures?
     
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  15. Jeff-6293

    Jeff-6293 Member

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    I don't see where to edit the TeslaFi layout. Can you specify?
     
  16. scaesare

    scaesare Well-Known Member

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    @ThisIsTrue, this is true.
     
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  17. Andyw2100

    Andyw2100 Supporting Member

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    If you look at the details of a drive, by selecting it, you will see all the data collected for that drive at, I believe, one minute intervals. At the top of the data should be an edit button.
     
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  18. ThisIsTrue

    ThisIsTrue Dismember

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    To not hijack the thread, here's my quickie trip report: 23 Days: 4400 miles

    And "Hey!" to a fellow Coloradan!
     
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  19. Jeff-6293

    Jeff-6293 Member

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    Thanks.
     
  20. S85D

    S85D Member

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    Andy, I have read in multiple threads that the battery heater comes on when plugged into shore power, range mode is off, and you start the climate control using the Tesla phone app. If you are not using the phone app, you might want to try that.
     

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