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Battery warmer energy usage

Discussion in 'Model S: Battery & Charging' started by Jeeps17, Oct 29, 2013.

  1. Jeeps17

    Jeeps17 Cath Jockey in a P85

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    Montreal, Canada
    Hello all,

    Now that the weather is getting colder, energy use has been going up significantly (this is noted in other threads).

    My specific question is about the battery heater, and its pattern of energy usage.

    I got my car last march, when the weather was similar to current conditions (if not colder), and my car was running v4.4.

    I seem to remember that when I would get into my cold-soaked car at the end of a day's work, I would get a single very large spike of energy from the battery heater, which would eventually taper down to my driving usage.

    These days (running v4.5), I seem to get multiple spikes of energy usage from the battery heater (my driving would certainly not cause them in Montreal traffic). An example photo below. The three last spikes occured during my drive home, the regen was back to normal (no limiter) after the third spike:

    photo.JPG

    Has anyone else noticed this?

    Is this behaviour present on those running newer OS versions (v5.0 or 5.6)?

    As usual, thank you for your comments!
     
  2. zax123

    zax123 CDN Model S P308

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    Candiac, QC, CAN
    Hi Jeeps,

    Unfortunately, I don't have an answer to your question yet but I will monitor my energy usage -- which has definitely gone up since the cold washed in.

    I had a related question though. I want to be able to plug in my car and use shore power to heat the car and battery during the day/night but not necessarily charge the batteries. Is there a way to do this? Everyone will ask why I'd want to do this, so here's a scenario:

    I want to do most of my charging at work on the CS-90 I have here so I don't have to pay for charging at home. :) However, I only heat my garage to 15 degrees, so the battery warmer will turn on now and then and I'd like to use power from my HPWC to do that but not charge the batteries.

    Any ideas? :)

    Thanks and sorry to thread hijack -- I just thought it was loosely related and didn't want to start a whole new thread. Mods if you feel it should be separated, by all means...
     
  3. mnx

    mnx 2013 P85

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    Set the charge slider to a level below your current charge?

     
  4. zax123

    zax123 CDN Model S P308

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    That's an awesome idea! I'll try that and see if it still uses shore power for battery/cabin heating.

    Thanks!
     
  5. qwk

    qwk Model S P2681

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    I have noticed the same thing, as my car had been delivered about the same time as yours. The nice thing about FW 4.5 vs. 4.2 is the vampire and rated range displayed is worlds better with FW 4.5. On 4.2, when the temp went below freezing, the car displayed up to a 30 mile loss. Now with 4.5, its about 5 miles lost overnight whether it's 70*F or 22*F. Very consistent.
     
  6. Duckjybe

    Duckjybe S P232

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    I have noticed that during daytime temps of around 7 deg C and sunny (i.e. not a particularly cold day yet around here) my regen has been slightly limited for many minutes into my drive. I could be forgetting, but I do not recall this happening last winter/spring where regen limit would kick in only on the coldest of days (-10 deg C) or a full battery. I am now on 4.5. I wonder if the software is heating the battery in a gentler fashion now to save power?
     
  7. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    Sure. Here is a pretty easy work around: I assume that you have an HPWC with a full power 80 Amps available. If you set the current to a lower value, say 20 Amps, then the charge rate will only be 14 mph, but there is 5 kW available for heating the battery and cabin. Then set the charge start time to an hour or two before departure (there are also ways to fiddle with the App to do this). The charge will start before you leave, the battery will heat up (over an hour or so this will also nicely heat the cabin as a side effect), with pre-heating, you probably won't put in more than 10 miles in the battery, and all is toasty and warm. The car will remember the current limit, and I believe, the charge start time with the GPS location. All you have to do when you want to charge at home is reset the current limit and timed charging settings. Check to make sure there are no current limits or charge start limits at work.

    I heard another claim that turning on the cabin heater with the App will also pre-heat the battery. I have not tested that, but may give it a try sometime.

    BTW, I love it, a CS-90 at work and an HPWC at home! Charge On!!! :wink:

    Have Fun! :biggrin:
     
  8. mknox

    mknox Well-Known Member

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    Yep. Me too. In fact, the re-gen limit seems to say on a lot longer than I recall it doing last winter as well.
     
  9. zax123

    zax123 CDN Model S P308

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    Hey Cotton,

    Thanks for this. So the first thing I tried (just now at work) was I set my charge limit to 50% (while already being charged to 85%) and plugged in the CS-90 and walked away.

    Then I loaded up VisibleTesla (super cool app, love it), and checked that the car wasn't charging, and it wasn't. Then I went to the HVAC tab, and turned on cabin heat and checked the charging tab and sure enough, the car started to draw about 11 amps from the CS-90. That's exactly what I want.

    However, I have no way of knowing if it is drawing current to heat the batteries. I'm assuming it just randomly heats batteries when they get cold. I'll keep VisibleTesla open and hopefully it's graphs will show me a spike in current draw from shore every now and then when the battery heater pops on, but that remains to be seen...

    This car is so much fun. :)

    -- Rob
     
  10. Jeeps17

    Jeeps17 Cath Jockey in a P85

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    So far in my experience this year this has not been the case - I pre-heat my car for 20-30 minutes before I leave work, and get the full regen limiter / multi-spike warmer use posted above.

    It would be a great idea though.
     
  11. J in MN

    J in MN S60 P12635

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    Plus max regen is always much less than the yellow line.
     
  12. mknox

    mknox Well-Known Member

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    Yes, I notice that too...
     
  13. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    I have never seen more than half...
     
  14. donv

    donv Member

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    I actually believe that pre-heating the cabin does heat the batteries, at least somewhat. I keep my car in a carport, so roughly outside temperature. When it's in the low 40s, as it was this morning, running the climate control for 15-20 minutes seemed to prevent the regen limit. Yesterday morning, same temperatures, didn't run the climate control, and I got the regen limit.

    Maybe it just isn't enough in really cold temperatures?

    Would charging for a few minutes heat the battery?
     
  15. digitaltim

    digitaltim Sig737 VIN628

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    Yes - I typically remotely toggle the charge to a range/max charge 10-15' before I am ready to leave on a cold day.
     
  16. Peter_M

    Peter_M Member

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    Does anyone know if you can pre-warm the battery without being plugged in? I'm getting regen completely disabled every day on the way home from work when it's cold (-20[SUP]o[/SUP]C), even if I turn on the climate control 30-45 minutes before I leave. I'd be happy to burn some range to have regen on the way home. It's possible that turning on the cabin heat does warm the battery, just not enough. I wish we had a battery temperature reading in the app...
     
  17. Peter_M

    Peter_M Member

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    Well I think I've answered my own question. Today I turned Range Mode off, drove to work and left the car unplugged for about 6 hours at -24[SUP]o[/SUP]C. Then I turned on climate control with the app, left it for 1/2 hour, then when it turned itself off, I turned it back on for another 25 minutes. When I got to the car, it was toasty warm inside, there was no power limit, and the regen limit was about 25kW, enough to drive one-footed most of the time. By the time I got home (about a 30 minute drive), the regen limit was almost gone. So I'm happy to say that it is possible to almost eliminate the power and regen limits even when unplugged. One thing I'm not sure about is whether Range Mode was a factor. Next time it's this cold, I'll try it again with Range Mode off.

    One caveat, though - the car burned 13km of rated range sitting for the 6 hours (apparently it did some pack warming on its own), and then another 24km warming up for 55 minutes, and quite a bit more than the distance on the way home. So it costs you in range, but it works if you've got the juice.
     
  18. Jeeps17

    Jeeps17 Cath Jockey in a P85

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    I think the use of range mode was the culprit here.

    Since I turned it off, pack heating has been more consistent (single large spike).

    As noted by Peter and others above, the cost in range can be significant, especially when temperatures stay below 20C and the pack is cold-soaked. Add short trips to that mix for maximum loss...
     
  19. Peter_M

    Peter_M Member

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    Yes, I confirmed this today. With Range Mode on, after warming the car unplugged from only about -5[SUP]o[/SUP]C for 1/2 hour, I still had a power limit, regen completely disabled and the "battery is warming" warning.
     
  20. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    At -5[SUP]o[/SUP]C this morning, I had a regen limit but no "battery is warming" message. It did take almost an hour's driving to fully get rid of the regen limit. I was in range mode and the car was pre-heated for about 45 minutes--right up to when I started driving, and the charging ended about 30 minutes before driving. Note the car is parked outside. Wh/mile got up to 265.
     

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