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Power drain while idle (Vampire Load)

Discussion in 'Model S: Battery & Charging' started by dennis, Nov 10, 2012.

  1. dennis

    dennis P85D

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    We've had our Model S for about 10 days and love it! One thing I noticed is that if the car is not used or charged for 24 hours it loses about 10 miles of indicated range. This is without opening the doors or otherwise turning the car "on" in any way.

    Is this normal behavior? Any idea why it uses 3 kwh per 24 hours?
     
  2. Doug_G

    Doug_G Lead Moderator

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    This has been noted on other threads. Reportedly Tesla is working on firmware upgrades to improve it. The extra draw is due to the need for the car to boot up immediately; they're keeping more stuff running than they originally planned on. With judicious idle power management they should be able to resolve this.
     
  3. Tommy

    Tommy Member

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    Hope they fix it ASAP, it's an extra $14 a month draw at my lowest rates. That's before it even travels a foot outside the garage.
     
  4. pilotSteve

    pilotSteve Member

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    +1 Tommy, Doug_G: I was surprised at the $14/month cost. Did the math myself and I agree with your numbers. My power in the Pacific Northwest is cheaper at 0.09/kWh but still its $8 per month. Whoa, yes I also hope this is remedied.

    Its like running 500W electric 'space heater' in your garage 6 hours every day! (3000/500=6). Atsa lotsa watsa!
     
  5. Zextraterrestrial

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    ~$30 for me
     
  6. dsm363

    dsm363 Roadster + Sig Model S

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    Once the proximity sensor senses you getting next to the car, it should have a few seconds at least to turn some of the other systems on. Hopefully then can reduce the energy used just sitting there.
     
  7. bint2k

    bint2k Member

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    subscribed =)
     
  8. jerry33

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

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    Even without the proximity sensors, if it started powering up to off from sleep mode when the driver's door was opened, it would still have plenty of time to do that. A precedent is the Prius brake pump. It starts as soon as the driver's door is opened to pressurize the power brake system. Works fine. And using the driver's door opening (or unlocking) as the trigger might be better than a proximity sensor because you likely don't want the car using power if you're just walking by it to take out the trash or something.
     
  9. pilotSteve

    pilotSteve Member

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    My E60 BMW (2006) attempts to balance wake-up time with battery consumption. 80% of the time the iDrive screen takes 5-10 seconds to come alive, other times its like a full reboot (20-30 seconds). I appreciate Elon's effort to always make it 'instant' but this is a solution that probably has unacceptable cost.

    Will be interesting to see what Tesla's approach to balance wake-up vs. battery consumption turns out to be.
     
  10. Doug_G

    Doug_G Lead Moderator

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    Most microprocessors have low-power idle modes, sometimes various alternative modes, where the processor goes to sleep until an interrupt occurs. If they can put processors to sleep this way then they can have very low-power idle and instant wake-up. They might have to do some firmware magic to get it to work, but that's a "simple matter of software" (quotes are for irony purposes). That's what "sleep" mode is on your notebook computer.

    Another alternative is to write the image of the computer memory out to nonvolatile storage. That's what your notebook computer does in "hibernate" mode. Not quite as fast to boot up, but faster than a full restart. Mind you, the Model S has flash memory, not disks, and there may not be enough storage to do that. Even if there is enough storage, there are issues about flash memory durability etc.
     
  11. ElSupreme

    ElSupreme Model S 03182

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    On a related note I finally got my home desktop to sleep properly. I am now saving about $15 a month in power (probably only about $10 since I turned off my AC)! So yes these things do consume real amounts of power.
     
  12. arg

    arg Member

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    Yes, but this doesn't really match up with the loads people are reporting - even if left fully running, these CPUs would only be a couple of watts, yet people are reporting figures like 500W. We know that the two 'big' processors running the instrument display and touchscreen are Nvidia Tegra (as used in tablets) which have idle power management in normal operation. Those are probably the only processors in the car running a heavyweight OS that would need significant reboot time.

    So, it could be something mechanical causing these loads (someone upthread mentioned brake servos, also there's battery cooling), or it's death by a thousand cuts in all of the minor subsystems contributing the odd watt here and there and just adding up to a big total. It may be a long slog to fix it rather than a single big win.
     
  13. Ceilidh

    Ceilidh Member

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    Seems to me that Tesla could make this user-selectable. Clearly the instant on capability is there is your are less energy / cost conscious. Would be nice to have an eco-mode for this that turns the car off unless the battery temp needs to be adjusted, but otherwise turns on when the door is opened or when the driver sits down or something. Shouldn't be too hard to program given that the sensors are already in place and such.
     
  14. brianman

    brianman Burrito Founder

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    Maybe they should hae some kind of, well, "Storage Mode"... ;)
     
  15. DrComputer

    DrComputer Member

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    I also think people have taken the "lost 10 miles in 24 hrs" number at face value. The S, just like the Roadster does not always show accurate mileage estimates after charging. It takes some time for the battery pack to settle and balance itself after charging. I think the actual loss is probably closer to 1 mile per day than 10.
     
  16. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    Let's hope so. I live 60 miles from the airport and I take business trips that average 10-14 days long. I'd hate to come back from my trip and find that I don't have enough miles to get back home. :)

    Of course, I've found a couple of airport parking facilities that will let me have a NEMA 5-15 while I'm parked there, so I think I've mitigated that concern -- but if they're occupied or busy, I might have to bank on my miles still staying up there.
     
  17. rolosrevenge

    rolosrevenge Dr. EVS

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    Unless, of course, you would have been running that space heater anyways (it's cold up here), then it is costing you nothing.
     
  18. vfx

    vfx Well-Known Member

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    Maybe this type of software upgrade is why they have not opened the memory to owners yet.
     
  19. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    That is exactly what I have seen. There is a big drop the first day after charging, then a much slower drop on succeeding days. Am I the only Model S owner that has gone multiple days without driving it? :biggrin:
     
  20. dsm363

    dsm363 Roadster + Sig Model S

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    I think you'll be fine even without charging but of course if you have it, take advantage of it at the airport.
     

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