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Tesla Model S Has Bizarre 'Vampire-Like' Thirst For Electricity At Night 424

cartechboy writes "The Tesla Model S, for all its technical and design wizardry, has a dirty little secret: Its a vampire. The car has an odd and substantial appetite for kilowatt-hours even when turned off and parked. This phenomenon has been dubbed the 'vampire' draw, and Tesla promised long ago to fix this issue with a software update. Well, a few software updates have come and gone since then, and the Model S is still a vampire sucking down energy when it's shut down. While this is a concern for many Model S owners and would be owners, the larger question becomes: After nine months, and multiple software updates,why can't Tesla fix this known issue? Tesla has recognized the issue and said a fix would come, yet the latest fix is only a tiny improvement — and the problem remains unsolved. Is Tesla stumped? Can the issue be fixed?"
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Tesla Model S Has Bizarre 'Vampire-Like' Thirst For Electricity At Night

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  • by fuzzyfuzzyfungus ( 1223518 ) on Tuesday November 26, 2013 @01:11AM (#45523113) Journal
    They didn't go overboard in computerizing the thing and incorporate ACPI, did they? That would be more than enough both to explain the mysterious power drain in sleep, and the utter inscrutability of the problem...
  • Vampires? (Score:5, Funny)

    by FredGauss ( 3087275 ) on Tuesday November 26, 2013 @01:11AM (#45523115)
    Is Tesla stumped? Can the issue be fixed? Tune in tomorrow — same Bat-time, same Bat-channel!

    But on a serious note - I'm pretty sure the issue has something to do with this: []
  • New name (Score:5, Funny)

    by Anonymous Coward on Tuesday November 26, 2013 @01:11AM (#45523123)

    Now known as Lestat model S.

  • Vampire? Huh?! (Score:3, Interesting)

    by tibit ( 1762298 ) on Tuesday November 26, 2013 @01:12AM (#45523129)

    Vampire-like? Huh? Are we dumb kids here or sum'thin'? This is beyond anthropomorphization, man.

    The energy has to go somewhere. They have power management on that car, as well as engineering telemetry. They know exactly where it goes. Let's cut the bullshit. As far as I can tell from how it looks, the energy is needed for something. I don't know what, maybe the batteries have high leakage, whatever, but it's not like the energy evaporates. The power/charge management system needs this energy, and what they are fixing is not some random energy drain - they are trying, and failing, to fix the underlying cause that is not easy to fix. I don't know if it's a design issue in electronics, or a battery issue, or what. But one thing is for sure: they know exactly where all those kWh end up at, but they're failing at resolving it. If the drain was significant on cold nights, I'd say that it goes into battery pack heaters.

    • Even if they didn't know where it was going, you could find out with a cheap multimeter within an hour or two.

      • by Anonymous Coward on Tuesday November 26, 2013 @01:25AM (#45523217)

        That's the problem. The engineers at Tesla have the really expensive multimeters.

        • Re:Vampire? Huh?! (Score:5, Interesting)

          by thegarbz ( 1787294 ) on Tuesday November 26, 2013 @06:22AM (#45524453)

          I know you joke but we've had some engineers truly stumped and raising all sorts of wonderful alarms due to this very issue. Fancy expensive multimeters with internal resistances in the >10s of GOhms. They've tested for dead on the cable and the cable measured some 70V. I went and got an ancient analogue meter and it measured zero. Naturally it was my meter that was "broken". So we made a bet. $100 that I put a 24V bulb on his 70V cable and it wouldn't even light up briefly.

          Turns out the cable was picking up noise which presented a voltage to the very expensive meter, but we were talking about only microwatts. I was $100 richer and my ancient analogue meter got some real cred.

          Had a similar issue on a 24V supply where one engineer was insisting that we didn't turn off the correct battery bank because he was still measuring 24V. Turns out that leakage current back from the other bank was causing the reading which again wouldn't have been a problem if he didn't have such a damn good multimeter.

      • Re: (Score:2, Troll)

        by NIK282000 ( 737852 )

        I wouldn't go poking around with a cheap meter in an electric car, the potential to have many thousands of amps turn chinese test equipment into several cubic meters of hot gas is too big. With a slightly more expensive meter (200-300$) you can do clamp on current measurement AND keep all of your body hair!

        However I think the people who have the cash for a Tesla might not be the same kind who like to service their own cars. You never see anyone change the oil in their Merc on the driveway. They pay

        • by cheater512 ( 783349 ) <> on Tuesday November 26, 2013 @01:38AM (#45523291) Homepage

          Nah a cheap one would work fine.

          If the cheap meter explodes *while the car is off* you know you are on the right track.

          • Re: (Score:2, Funny)

            by sjames ( 1099 )

            That's a feature. It did say it has an audible continuity test on the package. I'd call an arc explosion audible.

        • With a slightly more expensive meter (200-300$) you can do clamp on current measurement AND keep all of your body hair!

          Why so expensive? A clamp on probe costs $40 on ebay, will work with any cheap multimeter.

          If you want to go even cheaper, all you need is a self-wound coil (50-100 turns will do) around an iron C-clamp, three resistors and a capacitor.

      • Poking around a large lithium battery with a cheap multimeter at night. That's got Darwin Award written all over it. Maybe try a Hall Effect current probe. Not as cheap, but less likely to kill you.
        • There's that concept called "high impedance" you should probably be looking into.

        • What are you guys considering cheap? My cheap $50 meter has a current probe. $50 is dirt cheap by Fluke standards.

      • Even if they didn't know where it was going, you could find out with a cheap multimeter within an hour or two.

        I could do it even faster. Just feel around for something that is hot. That is where the energy is going.

        • Re: (Score:3, Insightful)

          by Anonymous Coward

          Or use an infrared camera on a cold night.

    • "but it's not like the energy evaporates"

      You mean 'dissipates', and yes, it does, as heat. Poof, right into thin air. In other news, Tesla owners reconsider purchasing garage heaters.
    • Re:Vampire? Huh?! (Score:5, Insightful)

      by Anonymous Coward on Tuesday November 26, 2013 @01:55AM (#45523379)

      I'd look for heat.

      That amount of energy drain will be making something warm.

    • Re:Vampire? Huh?! (Score:5, Informative)

      by immaterial ( 1520413 ) on Tuesday November 26, 2013 @02:03AM (#45523401)
      Modded 5 for random speculation.... Good old Slashdot. TFA says exactly where the power goes: the car's electronics don't sleep when the car is off.

      It seems that the "sleep mode" in the original Model S software--the basis for the owner's manual statements--had caused so many glitches in other car functions that it had been disabled. With sleep mode missing from the current v4.2 software, he said, I could expect to lose about 8-10 miles of range per day when unplugged.

      No big mysteries here. Room for complaint that this issue hasn't been resolved quickly, though.

      • Re:Vampire? Huh?! (Score:5, Insightful)

        by timeOday ( 582209 ) on Tuesday November 26, 2013 @02:28AM (#45523527)
        I find this wrinkle hilarious, out of sympathy. I have never, EVER, in the course of using probably 10 laptops over the last 10 years, had one on which suspend/resume actually worked right. Many that worked a few times, or even a couple weeks, or that worked unless I used a docking station, or 3d acceleration, or WiFi. And yes, that includes my i7 MacBook Pro running OSX; plug and unplug the external display and network enough times, and sooner or later it will forget to wake up when you open the lid.
      • by Chrisq ( 894406 )

        Modded 5 for random speculation....

        ... that the first law of thermodynamics applies to the Tesla

      • Re:Vampire? Huh?! (Score:5, Interesting)

        by LateArthurDent ( 1403947 ) on Tuesday November 26, 2013 @11:57AM (#45526639)

        No big mysteries here. Room for complaint that this issue hasn't been resolved quickly, though.

        Your quote is from the original article from March. In the next link he talks about the latest November update, which reintroduced sleep mode.

        That said, he's wrong that the latest update doesn't fix the problem. I own a Model S, and I went from losing about 5 miles off my rated range in 8 hours to losing about 1 mile per 14 hours. So, what's the difference between my car and his? Well, based on the pictures he posted, which has snow on the ground, he lives somewhere far colder than South Carolina, where I live. So his car is using more power for thermal management of the batteries.

        But wait, you say. The article says, "It's a popular myth among Model S owners that much of the vampire power goes to keep the battery warm during cold nights. This is simply not true. According to Tesla, there is no thermal management of the Model S battery when the car is turned off and not charging--no matter how cold it gets."

        True, guy. However, let's examine your testing methodology: "For each test, I charged the car up in the evening to its usual selected level (In my case, about 80 percent). Then I removed the charge plug. I allowed the car to sit unplugged overnight and on into the next day, until I needed to drive it. (Typically a span of 12 to 24 hours.) Before driving it, I plugged it back in to top off the vampire-depleted battery back to its original level. Then I checked the kWh-meter."

        And...when you plug it in to charge it, the pumps come on, and they start heating up your battery for safe charging. There's your so-called vampire load. My car, in a warmer environment, doesn't have to spend as much energy doing that.

        Furthermore, he says: "The three tests showed vampire losses of 2.3 kWh in 17 hours, 1.9 kWh in 23 hours, and 4.2 kWh in 18 hours...I can't explain the wide variation in the vampire draw over the three tests."

        Maybe he should try correlating it with temperature.

  • kWh/day is stupid. (Score:3, Insightful)

    by Anonymous Coward on Tuesday November 26, 2013 @01:19AM (#45523175)

    Why use kWh/day when we can use W? Do these guys really not understand units, or is there some silly love for kWh/day?

    This just makes me cringe:
    "[...] 4.5 kilowatt-hours per day. That's the equivalent of three 60-watt light bulbs burning 24/7."

    Couldn't he just say "190 watts"? (Or 180 W if he wanted to round incorrectly to match the light bulbs example).

    • by stanjo74 ( 922718 ) on Tuesday November 26, 2013 @01:31AM (#45523263)
      Yes, it's clumsy, but Watts doesn't tell you readily how much you are paying for it. Consumers are billed for kWh, so to express the cost of the drain, they used kWh/day; example: 4.5 kWh/day * $0.20 per kWh = ~ $1/day
    • by Anonymous Coward on Tuesday November 26, 2013 @01:38AM (#45523293)

      No, because it's not using '180W'. It's using the equivalent of 180W draining for 24 hours. Compare with 180W draing for 5 minutes, the time component is important.

      • by nyet ( 19118 )

        No. Power consumption is typically measured in watts, not joules, since power is generally more useful as a rate measurement than energy.

    • by gl4ss ( 559668 )

      well, no.

      or he would need to say that it burns during the nights times the equivalent of running 180watts 24/7.

      and since electricity is billed in kwh why not go with that...

    • by Anonymous Coward on Tuesday November 26, 2013 @01:53AM (#45523365)
      If you read the whole article, it's clear the guy doesn't have a clear understanding of how anything works.

      Right off the bat when he compares the Tesla's range estimate at the end of the day (when the batteries are warm) with the one the next morning (when the batteries are cold) I was already shaking my head. Fortunately the article later includes the explanation from the Tesla rep, but therein begins the pattern: long-winded article going on about this guy's half-assed attempts at figuring this out, punctuated by sensible explanations from the Tesla rep. The whole article could have been summarized thusly:

      The owner's manual told me I should be losing about 1 percent charge per day. When I noticed this didn't seem to be the case, I called Tesla and discovered that the sleep mode used for the car's electronics were causing issues at startup, so the latest software temporarily disables sleep mode resulting in larger power draw when the car is off (this sucks, and they should fix it faster!). The Tesla rep told me I should lose around 10 miles of range per night, but using a meter on my charger I discovered I lose more like 16 miles of range per night. Hurry up and fix this, Tesla."

      And why does he seem to lose more juice than the Tesla rep's estimate? (1) Tesla's estimate is likely an average and isn't specific to the cold overnight conditions this guy has (the system's drain on a cold battery will be harsher), and (2) he's measuring how much THE CHARGER is using in the morning, and he says himself that the charging system needs to warm up the batteries before charging, so he's measuring lost power PLUS the power needed to warm the system.

    • by nyet ( 19118 )

      The average PC draws around 50-200W idle.

      And as you said, this is more or less what the author found, except that he apparently has no idea how to convert kW/h per hour into watts. And for some reason, he's using lightbulbs as a yardstick, and not a PC... which is, after all, basically what is running on the tesla 24/7

      Yes, he's a fucking moron.

      • by Poingggg ( 103097 ) on Tuesday November 26, 2013 @07:35AM (#45524771) Homepage

        The average PC draws around 50-200W idle.

        And as you said, this is more or less what the author found, except that he apparently has no idea how to convert kW/h per hour into watts.

        Yes, he's a fucking moron.

        Sorry, but you are wrong her. First, it's KWh (KiloWatthour), not KW/h.
        The Watt is a unit that is used for measuring the amount of energy used per unit of time, in short 1 Watt = 1 Joule per second.
        When electric energy is stored, like in a battery, or measured, the total energy stored or used is derived by multiplying Watts by time, thus Watt * seconds. Since this is not an easy workable unit, KiloWatts are multiplied by hours, and there we have the KWh.
        So, if a battery has a capacity of 100 KWh, it is able of delivering 1000W for 100 hours, 500W for 200 hours, 100W for 1000 hours and 1W for 100,000 hours.
        So, to make a long story short, the lost capacity of a battery HAS to be expressed in KWh, and the resulting loss of range totally depends on the driving conditions. It might be (numbers pulled from lower opening of intestine) 100 km when driving a constant 20 km/h, or 5 km when driving a constant 150 km/h, since the amount of power drawn on these speeds vary. But I hope you get the picture.

        The qualification as a copulating, low-IQ person is totally yours.

  • From TFA:

    Since the Model S was introduced in 2012, this "vampire" power drain from the cars sold so far has consumed roughly 15 gigawatt-hours of electric energy, nearly a day's output for a mid-size nuclear power plant. It's enough wasted energy to drive the cars 50 million miles.

    Seems odd that I've never heard this before now. That's a lot of wasted electricity that was generated, more than likely, by oil/coal burning.

    • Since power plants are totally overspecced for the nighttime consumption, you can rest assured that this electricity, which would have been wasted, is happily helping line the coffers of your local utility.

    • by geogob ( 569250 )

      You like numbers without perspective? Lets have some more, we could write further sensationalistic pseudo-journalistic articles on the internet.

      There are about 114 million TV sets in the USA. In average they use about 10 W of power on standby. Let say they are on standby 20 hours per day... I let you calculate how much electricity was wasted there in the same period.

      hint: it's more in a day than all the model S sold so far. Perspective helps to understand...

      • You might be a little high on an average of 10W on standby []. The limit has been 1W since 2010, and is .5W starting this year.

        But yeah, I wouldn't be happy with the car I bought to be energy efficient burning almost as much power as I need for my daily commute every day.

        • by geogob ( 569250 )

          I bet the average television is "old" by the standard given in wikipedia.

          • Probably so, but while details are lacking, vampire draw has been dropping for decades, and took a BIG hit with the switch from CRT to LED. I know I metered my 2008 LED TV and it's standby was 2 watts.

  • by istartedi ( 132515 ) on Tuesday November 26, 2013 @01:24AM (#45523215) Journal

    They used to tell us that if technology ever got out of hand, we could always pull the plug.

    Of course you are asleep when the problem occurs. If this were a low-wattage appliance you could just use one of those timers that people use for Christmas lights. You might be able to hack a heavy duty version of that by using a timer that moves a lever that knocks a bowling ball off a shelf. The bowling ball is tied to the Tesla power plug. That oughtta do 'er.

    Ahh, but you say the Tesla doesn't always take the same time to charge? Easy. You just need to program it to tweet charge state to your phone. Then your phone can send something to the device that pushes the bowling ball off the shelf that pulls the plug.

    Oh, but wait. Tweeting the location of your car isn't secure, and you may not have access to the car's APIs anyway. Besides, they're buggy and suspect.

    So. You need to have a separate secure device in the car that monitors the charge state, and logs in to your web site with HTTPS and relays that information securely to the device that pushes the bowling ball off the shelf that pulls the plug.

    There. All fixed. I just hope the ball doesn't roll off the shelf the wrong way and dent the car. To make sure that doesn't happen we need...

  • by Crashmarik ( 635988 ) on Tuesday November 26, 2013 @01:27AM (#45523233)

    What does it do roam the roads by night draining the life out of Priuses ?

  • I'm not sure about the Tesla batteries, but most rechargeable batteries need an "over charge" to get to 100% full.

    If the charger stops at the "full" mark (as indicated by Volts or A/H's) the batteries will be only be at about 80% full.

  • Many types of batteries have a low enough internal resistance to self-discharge when not in use. Nickel-cadmium batteries are notable for a high self-discharge rate. But lithium batteries generally have a low self-discharge rate, only a few percent a month. This Tesla owner is reporting something like 5% discharge overnight. That's a huge self-discharge rate for any modern battery chemistry.

    Tesla's battery has a series-parallel arrangement, and if some cells fail, they could drag down the rest of the pa

  • by NIK282000 ( 737852 ) on Tuesday November 26, 2013 @01:38AM (#45523289) Homepage Journal

    Tesla is renting the cars out at night using Google's self driving technology and Google maps to run a secret taxi service. That guy reported 10-15 miles of charge missing overnights, that could be a few fairs used to pay for more of Tesla's research.

  • by fahrbot-bot ( 874524 ) on Tuesday November 26, 2013 @01:42AM (#45523309)

    ... and given their recent tendency to burst into flames after a few simple bumps and scrapes, the cars are probably just spending their evening hours trying to sign up for coverage at :-)

    • by AaronW ( 33736 ) on Tuesday November 26, 2013 @03:49AM (#45523833) Homepage

      I think hitting a steel tow hitch at 70MPH is more than a little bump, or going through a concrete wall at 100MPh. People are blowing the fires all out of proportion. If a standard ICE car hit something like that in the engine compartment there's a good chance of a fire as well. In this case, since the battery is under the passenger compartment, a more likely scenerio would be for the debris to punch right through the floor and into the passenger compartment. Not one of the fires resulted in any damage to the passenger compartment of the car which cannot be said for most gasoline car fires I've seen.

  • by PaddyM ( 45763 ) on Tuesday November 26, 2013 @01:56AM (#45523389) Homepage

    Years ago, Tesla, or Nicola Tesla as he was known, sent transmissions from the Wardenclyffe tower into the air, forever altering the electrical potential of earth's ionosphere. This potential remained as it had no path to the ground. Until, that is, cars powered by batteries with his namesake appeared. At night, this leftover induction discharges batteries of the Tesla Model S and will continue until the potential is balanced.

  • by bidule ( 173941 ) on Tuesday November 26, 2013 @02:01AM (#45523397) Homepage

    cartechboy reports for, also mentioned in a forum post by Could it be an orchestrated campaign? No, impossible!

  • by foobar bazbot ( 3352433 ) on Tuesday November 26, 2013 @02:04AM (#45523407)

    I used to think I'd have to drink blood or something to be a vampire, but no. I've now learned that since my stomach is full when I go to bed, and gets emptier while I sleep, leaving me hungry and in need of a little refuelling in the morning... that makes me a vampire!

    • Well, you found yourself here, eh? You're aware Slashdot is a front for vampires anonymous, right? That's why we drum up fear about Zombies as a distraction...

      You didn't notice the other symptoms besides Anomalous Cravings? Aversion to sunlight, living in a basement, not bathing in (holy) water.
      I mean, you never wondered about that whole shrieking at Cross bearers thing?

  • by angrygretchen ( 838748 ) on Tuesday November 26, 2013 @02:10AM (#45523443)

    Tesla Model S uses a proximity sensor to detect the key fob in your pocket and extend the door handle with a motor: []

    To quote from an article:

    "From the instant you walk up to the Tesla S and the door handles motor out of the door, you know this isn't going to be like any other car you've ever driven. You open the door and the air conditioner has fired up, and your music is already playing. You put your foot on the brake, shift into gear, and you are off and running. There is no âoestartâ button. When you arrive, you just get out of the car; it turns itself off and locks up as you leave."

    Tesla originally had a sleep mode for the inboard computer that was supposed to consume around 1%/day. But they found that the sleep mode often resulted in the car not detecting the key fob. So they disabled it until they could patch it. Not surprisingly, it sucks a lot of power while its sitting in non-sleep mode waiting for someone to walk by with the right key fob. If they had stuck with a manual door handle and a push start button for the engine, then the idle power issue would never have come up. In any case, Tesla is working on it and will resolved it eventually.

  • by bernob ( 3444295 ) on Tuesday November 26, 2013 @02:11AM (#45523447)
    This is fixed in the european version of the software (I am a Model S owner in Norway). But the downside is that contacting the car with the Tesla App takes a bit longer and doesn't always work (the car needs to wake up to respond). I would guess they are having trouble with keeping the car polling their server while shut down. This is not "a real problem" in europe, as they have not released the app for europe yet (I'm using the american version to contact my car).
  • by sjames ( 1099 ) on Tuesday November 26, 2013 @02:55AM (#45523635) Homepage Journal

    If you find your electric car fully discharged in the morning, check for bite marks.

  • WTF (Score:2, Informative)

    by Mad Quacker ( 3327 )

    This poorly written article is from March. The problem has already been solved. Why I am reading this on slashdot now?

    "In other news, George Clooney reports his iPhone 1 had a bug in 2007"

    • by makomk ( 752139 )

      Did you actually bother to click on the second link [], written yesterday, which is all about how the problem is still there even after the supposed fixes? Be sure to read the second page too.

  • by bradley13 ( 1118935 ) on Tuesday November 26, 2013 @02:58AM (#45523645) Homepage

    According to the article, Tesla disabled the "sleep" mode of the onboard electronics, because it was buggy. As a result, they are running 24/7. Apparently, Tesla hasn't managed to fix the bugs with the sleep mode yet.

    This is a perfectly explainable problem - no need to go all vampiric about it. It's a software (or possibly firmware) problem that they will undoubtedly sort soon enough.

    • by AaronW ( 33736 ) on Tuesday November 26, 2013 @03:56AM (#45523867) Homepage

      The last software update (5.8) has improved things. From what I understand, power management with the Tegra 3 processor which is what the touch screen uses is rather broken. I talked with at least one developer who said that his company abandoned the Tegra 3 due to nVidia's horrible software management, providing non-working build environments and whatnot and that they don't give a changelog or seem to do any sort of version control.

  • Nine months is an *extremly short* round trip time in the car industry is a problem does not threaten the safety but involves controllers which probably affect the safety. (imagine fixing this bug, but introducing a side effect which turns the power off at full speed on the Highway)

    OTOH it should not have happened at all.

Given its constituency, the only thing I expect to be "open" about [the Open Software Foundation] is its mouth. -- John Gilmore