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Phantom drain in cold

Over the last couple of days it's been fairly cold here- highs around 30F or so and cloudy (so, internal car temp is also around 30F). While parked at work (outside), I've been seeing phantom drain at a rate of 5mi/hr, instead of my usual 0.4mi/hr. No sentry or summon or anything on; haven't changed any settings. I can't say I recall seeing this kind of drain last winter.

Is anyone else seeing this kind of drain when it gets cold?
 
do you have any cabin protection settings enabled? have you been using any tracking websites to gather stats on your battery, etc?

Yes, I have cabin overheat enabled, but AFAIK it doesn't do anything in cold.

Yes, I use Stats app, but as I said, I have not changed anything here. And I'm only talking about when it's outside in the cold; drain when in the garage hasn't changed.

Edit: Also, just verified Stats app hasn't been updated in several weeks.
 
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jboy210

Well-Known Member
Supporting Member
Dec 2, 2016
7,145
4,876
Northern California
Over the last couple of days it's been fairly cold here- highs around 30F or so and cloudy (so, internal car temp is also around 30F). While parked at work (outside), I've been seeing phantom drain at a rate of 5mi/hr, instead of my usual 0.4mi/hr. No sentry or summon or anything on; haven't changed any settings. I can't say I recall seeing this kind of drain last winter.

Is anyone else seeing this kind of drain when it gets cold?

Remember, every time your check with the app you make the drain worse. The car will go into a deep state and shutdown most of the systems after a little while. But by checking on the app you keep waking the car up and starting up a lot of systems thus increasing the power drain.

The same can happen when you install apps which gather information. So get rid of any of those and leave it sit for a day and see what the results are.

Tesla Bjorn reports losing 1-2% per day with his car sitting in freezing Norwegian weather outside at the airport. But he says he only checks it once a week.
 

srs5694

Active Member
Jan 15, 2019
1,496
1,983
Woonsocket, RI
I just posted the following to another thread; it seems relevant here, too:

Be sure to not check your app too often. Whenever you do, the car will wake up (or be prevented from going to sleep), and no matter what the cause, a Tesla that's awake uses more power than one that's asleep. I don't know for certain if there's an interaction between wakefulness and temperature, but I think there probably is. I've noticed that when my car is awake and plugged in when the temperature is low, my EVSE (which is network-enabled and so records energy use for me) reports periodic brief bursts of electricity use; but when it's asleep, this doesn't happen. I haven't yet tried to track range loss when unplugged in the cold in awake vs. asleep conditions. My (very tentative) hypothesis is that the car is trying to keep the battery warm when it's awake, but it stops doing this when it's asleep. If it does the same when unplugged, then you'd see accelerated range loss when the car is awake in cold weather, but not when it's asleep. Note that I've had my car only since late March of this year, so my experience with cold temperatures is still limited. Also, I live in Rhode Island, just to help calibrate my climate. I have a driveway but no garage, so my car is exposed to whatever Mother Nature throws at it. I know you probably want to track what's happening so you can take action before you end up stranded, but I suggest you exercise restraint. In a worst-case scenario, when the Model 3's SoC drops below 20%, it goes into an ultra-low-power mode, so you should have enough power to reach an EVSE, or ideally a Supercharger, to get more juice to get home.

Note also that at least much of the reason Sentry Mode uses more power than not using it is that it keeps the car awake whenever it's in use. Thus, if my hypothesis is correct, the range loss associated with Sentry Mode will be much greater in cold weather than in warmer weather, since you'll get the hit not just of keeping the car awake per se, but also the hit of extra battery warming.

On the plus side, if the battery is warm, you'll get more in the way of regenerative braking, and in extreme cases better acceleration, since a cold battery performs poorly and will limit both of these features. Of course, you can wake up the car and precondition the cabin temperature a few minutes before you want to drive to get the same improvement.

FWIW, I noticed something similar, but not identical, with the Chevy Volt that I drove before my Model 3 -- over the winter, if it was plugged in when it was cold outside, I'd see brief spikes of electricity use every hour or two, so I suspect it was warming the battery when plugged in. If I unplugged the car, I saw no range loss, so I suspect that it was not trying to warm the battery using only battery power.
 
@jboy210 I appreciate the response, but I'm well aware of the effect, and was not checking the app at all.

Since I see no more than 1mi/hr when using sentry (car always on), there must be something else going on for it to be 5x higher than that.

Really, I'm looking for someone to corroborate my observation or refute it (same software version, same temps, no drain). Should have said I'm on software 40.2 (I think)
 
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My (very tentative) hypothesis is that the car is trying to keep the battery warm when it's awake, but it stops doing this when it's asleep.

That is an interesting theory that I hadn't considered and makes some logical sense. While I'm quite sure I didn't wake the car more than once in the last two days, I could certainly test your theory during the next cold snap (going to be warmer here the next few days).
 

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