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Tesla Model S Has Bizarre 'Vampire-Like' Thirst For Electricity At Night
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?"
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.
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.