Long term airport parking

[pt19713]

Also when the car is awake with HV pack connected, my speculation is all the cell balancing circuits are on, and Model S/X is notorious for much higher vampire drain than Model 3/Y due to how the balancing is designed. My 2021 Model 3 SR+ only uses around 1 mile per day in deep sleep (when car left undisturbed for multiple days and all usual culprits like Sentry, Cabin overheat protection off). 1 kWh/day is more like 4-5 miles per day, and that's a lot more.

Active cell balancing occurs when the vehicle is asleep, SoC > 85%, and cell imbalance is > 5.0 mV.

 

[stopcrazypp]

Perhaps I missed something about the discussion. I thought this was about a car that was locked and idle with the only power draw what was required to service the Tesla app.

250-300W you were discussing is when the car is awake and HV contactor connected. That was the context from my understanding. When the car is in deep sleep and HV contactor is disconnected, it obviously isn't consuming that much. Judging from my own car at 1 mile per day, that's only about 10W when asleep.
Note if you are constantly waking the car up with the app, that'll consume that 250-300W power until it sleeps again. Given it seems to average around 30 minutes to fall asleep (may vary a lot), you consumed the same as like 12-15 hours of sleep in just that short time from waking up the car once for the app (even if you only check up on it for seconds). So it makes a huge difference.

While there may need for some parts of the electronics to be on, I'm not following how it amounts to 250 W unless major processing is happening.
The 12V converter would use very little power unless there was a lot of power running through it and even then the losses are not very large in proportion. Such units are typically 95% efficent.

My understanding is the DC-DC converters are actually more efficient when running at rated load vs lighter loads. Also a converter like for your laptop that converts 120 VAC to VDC (usually around 19V) may be more efficient and be less susceptible to such variation in efficiency depending on load.

Without sentry mode on, why would the camera signals be processed? The cameras themselves take virtually no power, it's the processing that cranks many MIPS and uses many watts.

I don't know if the inputs are being processed in any way, but my impression from doing research on this matter is the 250-300W consumption is there whenever the car is awake, regardless of what the computer is doing. Note Tesla may not necessarily have power save enabled for the FSD chips, or it may be much more limited than what conventional laptop/desktops may do. If they have no power save enabled, it'll consume roughly the same power regardless of what process is running. The power save is done usually by dropping the clock frequencies and/or voltages or if there are multi-cores sometimes turning off some cores.

My concern is more about the use of power to keep the battery from freezing. I know it happens and someone has said it can be as high as 20°F. That means it can happen on my car in the weather I'm likely to see this winter. I'd like to know more about this so I don't end up with a dead car.

I'm not aware of the car warming the battery by itself while unplugged and in deep sleep (HV contactors disconnected). Also given Tesla seems to turn off many features when SOC reaches 20%, I imagine it'll do that also even if it does. Do you have links to evidence of it doing so? When the car is awake obviously it can do that (and it may wake itself occasionally to charge the 12V battery).
Actually in searching for examples, I see that Tesla shows the range "lost" to the cold that can be recovered in blue.
Tesla Model 3 Range Loss Overnight, Unplugged In Sub-Zero Temperatures

 

[coleAK]

Perhaps I missed something about the discussion. I thought this was about a car that was locked and idle with the only power draw what was required to service the Tesla app. While there may need for some parts of the electronics to be on, I'm not following how it amounts to 250 W unless major processing is happening.
The 12V converter would use very little power unless there was a lot of power running through it and even then the losses are not very large in proportion. Such units are typically 95% efficent.

Without sentry mode on, why would the camera signals be processed? The cameras themselves take virtually no power, it's the processing that cranks many MIPS and uses many watts.




My concern is more about the use of power to keep the battery from freezing. I know it happens and someone has said it can be as high as 20°F. That means it can happen on my car in the weather I'm likely to see this winter. I'd like to know more about this so I don't end up with a dead car.

The car does not actively warm the battery when parked and asleep

 

[ODWms]

I’m in Miami for the holiday, and I turned sentry on before I went to sleep last night At the hotel. Here I am, 9 hours later and I‘ve lost 1%. Something’s definitely changed over the last couple years.

 

[gnuarm]

250-300W you were discussing is when the car is awake and HV contactor connected. That was the context from my understanding.

The numbers from level 1 charging were used to speculate the size of the idle current.

When the car is in deep sleep and HV contactor is disconnected, it obviously isn't consuming that much. Judging from my own car at 1 mile per day, that's only about 10W when asleep.

I'm not sure what deep sleep is. What mode is the car in when it was otherwise idle and then woken by the app? In that state there is no reason to connect the batter to the rest of the car. The info for the app comes from the BMS.

Note if you are constantly waking the car up with the app, that'll consume that 250-300W power until it sleeps again.

Ok, that was the estimate from the level 1 charging losses. But this amount is very high without the video and other high performance processing active. What is the car doing when it is not being driven that uses so much power. 300 watts really is a lot of power in digital electronics. A raspberry pi uses less than 2 watts normally, a cell phone uses around 4 watts even when banging the wifi connection and a laptop uses around 30 or 40 watts, even with a graphics chip. See the point I'm making?

If the car is not on auto pilot and the cameras are not recording from sentry mode, the power drain should be far less than 300 watts.

Given it seems to average around 30 minutes to fall asleep (may vary a lot), you consumed the same as like 12-15 hours of sleep in just that short time from waking up the car once for the app (even if you only check up on it for seconds). So it makes a huge difference.

I can't see any reason to keep the car fully awake for 30 minutes. Where did you get that number? Even so, half a hour of 300 watts is just 150 Wh.

My understanding is the DC-DC converters are actually more efficient when running at rated load vs lighter loads. Also a converter like for your laptop that converts 120 VAC to VDC (usually around 19V) may be more efficient and be less susceptible to such variation in efficiency depending on load.

Don't confuse terms like more and less for numbers. Regardless, the 12 V battery would not be charged continuously. Rather it would be charged with a resonable current when needed from a converter designed to optimize the efficiency. Actually, laptop power converters run at lower power levels than the 12 V converted would be expected to produce and solve a different problem in converting from low frequency AC to DC. So not very comparible.

Dropping 400 VDC to 12 VDC is not a complex task and can be done very efficiently thanks to the batter that is being charged.

I don't know if the inputs are being processed in any way, but my impression from doing research on this matter is the 250-300W consumption is there whenever the car is awake, regardless of what the computer is doing.

What info did you find that indicated this? Where did you get your 30 minute number for returning to sleep?

Note Tesla may not necessarily have power save enabled for the FSD chips, or it may be much more limited than what conventional laptop/desktops may do. If they have no power save enabled, it'll consume roughly the same power regardless of what process is running. The power save is done usually by dropping the clock frequencies and/or voltages or if there are multi-cores sometimes turning off some cores.

By dropping the clock/voltages I assume you mean turn them off? There is no reason to run the FSD processors when waking from sleep with the car still in low power mode (i.e. no one in the car and not in drive). So the power to those circuits would be completely off.

I'm not aware of the car warming the battery by itself while unplugged and in deep sleep (HV contactors disconnected). Also given Tesla seems to turn off many features when SOC reaches 20%, I imagine it'll do that also even if it does. Do you have links to evidence of it doing so? When the car is awake obviously it can do that (and it may wake itself occasionally to charge the 12V battery).
Actually in searching for examples, I see that Tesla shows the range "lost" to the cold that can be recovered in blue.
Tesla Model 3 Range Loss Overnight, Unplugged In Sub-Zero Temperatures

I'm not trying to prove anything. I'm looking for information rather than people's opinion of what might be done.

 

[gnuarm]

The car does not actively warm the battery when parked and asleep

What is your basis for saying that? Where did you read that?

 

[coleAK]

What is your basis for saying that? Where did you read that?

8 winters with Tesla’s in Alaska.

 

[gnuarm]

8 winters with Tesla’s in Alaska.

You know that's not an answer. It's still anecdotal and you've said nothing about the temps under which you left the car unplugged or for how long.

Why are you playing at this?

 

[73zdriver]

Ugh yes the app wakes up the car.. just leave it unplugged, go out to your car and open the app.. clunk clunk... there go the hv contactors.

 

[coleAK]

Here is a an example of how cold effects the battery and range today. Started out the trip at 64% temp was 2F, car had been sitting for 16 hours or so plugged in to my charge connector (40a). Drove around town, went almost 10 miles and only used 1% and pretty much got rated range Wh/mi. Why? As the battery warms up from driving you get the % list due to cold back. I’ve driven 20 miles in sub zero temps and used no battery %.

 

[coleAK]

You know that's not an answer. It's still anecdotal and you've said nothing about the temps under which you left the car unplugged or for how long.

Why are you playing at this?

Almost every weekend at my cabin it is unplugged for 2-3 days even in the -20’s. I’ve left it unplugged for 2-3 weeks unplugged in the spring (still temps below freezing) and lost almost nothing. Like others have said, turn off everything and don’t check on it from the app.

 

[stopcrazypp]

The numbers from level 1 charging were used to speculate the size of the idle current.

I'm not sure what deep sleep is.

Deep sleep is just a term I use personally to mean HV contactor disconnected for sure. Sleep can mean the state when computer is still not booted up yet, but HV contactor is connected (like for example immediately after a wake command).

What mode is the car in when it was otherwise idle and then woken by the app? In that state there is no reason to connect the batter to the rest of the car. The info for the app comes from the BMS.

The car is awake fully when woken by the app. The info for the app does not come only from the BMS, all the subsystems have to be on because the app can control almost everything relevant in the car (including HVAC, which obviously needs the HV battery to operate).

Try it yourself sometime. Wait until the car is fully asleep (the "clunk" of the HV contactor has disconnected the battery). Then wake up the car with the app. You will hear HV contactor connecting again. There is no way to keep the car asleep and use the app to check on it (unless you close the app before it shows the "waking up" message, but that defeats the point, as the data shown is outdated).

Could Tesla design an intermittent mode that runs purely on the 12V battery (and then only connect HV when a feature uses it, so there may be a delay)? Yes, but they didn't.

Ok, that was the estimate from the level 1 charging losses. But this amount is very high without the video and other high performance processing active. What is the car doing when it is not being driven that uses so much power. 300 watts really is a lot of power in digital electronics. A raspberry pi uses less than 2 watts normally, a cell phone uses around 4 watts even when banging the wifi connection and a laptop uses around 30 or 40 watts, even with a graphics chip. See the point I'm making?

Again that's the drain just to have the computers on and all the various parasitic drains from the various subsystems (which may also have their own microprocessors running). All of the examples you give are pretty much self contained and are not comparable to a car.

If the car is not on auto pilot and the cameras are not recording from sentry mode, the power drain should be far less than 300 watts.

Note Sentry mode only detects motion and copies video files to Saved Clips. Even with Sentry mode off, Dashcam still records whenever the car is awake.

Myself personally, I notice no significant difference between Sentry mode vs having the car awake (for example when I have a trunk open or door open for hours working on things), it still consumes about 1 mile per hour, which works out to 200-300 watts.

I can't see any reason to keep the car fully awake for 30 minutes. Where did you get that number? Even so, half a hour of 300 watts is just 150 Wh.

An example is here, but plenty of people use 30 minutes as a ball park number as it ensures the car is almost always already asleep, but it can vary a lot (that article says it can vary from 6 minutes to 6 hours).
Drain, Drain, Go Away! Carmiq’s Approach to Managing Phantom Drain

150 Wh is a lot for checking the app for just one second. That is good for around 15 hours otherwise if you refrained from checking the app.

Don't confuse terms like more and less for numbers. Regardless, the 12 V battery would not be charged continuously. Rather it would be charged with a resonable current when needed from a converter designed to optimize the efficiency. Actually, laptop power converters run at lower power levels than the 12 V converted would be expected to produce and solve a different problem in converting from low frequency AC to DC. So not very comparible.

Dropping 400 VDC to 12 VDC is not a complex task and can be done very efficiently thanks to the batter that is being charged.

I'm not saying it's a complex task, just that DC-DC converters tend to be less efficient for smaller loads. Laptop adapters however are typically sized properly for the load and it has the advantage of an AC input and also a smaller voltage differential (which also helps efficiency). I know this from my own experience (part of my studies was EE).

If you want sources, I googled it quickly to find it for the Model 3:
You can see at 200W draw it can get a lower bound around 70% efficient. As you go toward 600W lower bound is more like 90%. There seems to be a 37W parasitic draw at all loads, so the higher the load the more efficient. In short, converting from the HV battery to 12VDC is not efficient for a small load.

https://www.reddit.com/r/teslamotors/comments/iws58g

What info did you find that indicated this? Where did you get your 30 minute number for returning to sleep?

This is from other forum posts discussing this. One example here, but there are plenty of other discussions where people claim the same.
Teslab workaround for 12v charging
Also see other paragraph about my personal experience comparing when car is awake (from at car with door/trunk open/closing) vs Sentry mode.
Edit, here's another reference I just found when looking at Summon Standby which also keeps car awake:

https://www.reddit.com/r/teslamotors/comments/gp8c2a/_/frkgc3c

If you don't believe this, it's pretty easy to do an experiment yourself. Have Sentry mode on, and see how much range you lose per hour (probably it is best to let it sit for multiple hours to let things average out). Then turn off Sentry mode and try to keep car awake (either by doors or keep waking it with the app when you hear the clunk) and see how much range you lose per hour. You should see no significant difference between the two.

Summon Standby also can keep the car the car awake.

By dropping the clock/voltages I assume you mean turn them off? There is no reason to run the FSD processors when waking from sleep with the car still in low power mode (i.e. no one in the car and not in drive). So the power to those circuits would be completely off.

AFAIK all the cameras are connected via the FSD board and it's the FSD processors that do the video encoding. Dashcam is always on when the car is awake (even with Sentry off and no one in car). I have not tried however if there is any difference with Dashcam off, but I don't intend to use the car with Dashcam ever disabled, so it's not something I will try.

I'm not trying to prove anything. I'm looking for information rather than people's opinion of what might be done.

Sorry, the way you worded it seems like you have experienced it yourself, but AFAIK, no one has reported the car ever waking itself to warm up the battery pack even in freezing temps (although if you wake up the car, it will try to warm the battery, just like it does as normal). The battery is pretty much seems to be allowed to cold soak.

Lithium ion battery electrolyte generally freezes at -22° F (-30° C) to -40 F (-40 C), which people rarely experience for long periods (keep in mind battery pack is a huge thermal mass, so takes a while to reach that temp even if ambient temp was that). Tesla manual says "Do not expose Model 3 to ambient temperatures above 140° F (60° C) or below -22° F (-30° C) for more than 24 hours at a time." Given it appears the the power converter in the car can run the heater off shore power, I imagine even if it allowed things to freeze, there are ways for the car to thaw the pack as long as you plug it in.
Model 3 Owner's Manual | Tesla

 

[RVJ007]

We’re going on a 10 day holiday in July.
We will be leaving our model 3 performance at the airport.
Does anyone have any suggestions for maintaining battery life for this duration.

Also do airports offer a charge facility for when you come to pick it up?

Gatwick is our airport.

 

[TW14 9LF]

For 10 days......park it and leave it. Turn off Sentry Mode, and try not to check up on it using the Tesla app while you're gone.

I've left mine at the airport while I'm on business for upwards of 2 weeks, with no issue. Battery lost about 8-10% of charge while sitting.

Keith

 

[jjrandorin]

We’re going on a 10 day holiday in July.
We will be leaving our model 3 performance at the airport.
Does anyone have any suggestions for maintaining battery life for this duration.

Also do airports offer a charge facility for when you come to pick it up?

Gatwick is our airport.

I wasnt sure where "gatwick" airport was, but when I googled "charging at gatwick airport", I got the following link. Perhaps this might help you.

Parking FAQs | London Gatwick Airport

Frequently asked questions about parking at London Gatwick and booking Official London Gatwick Parking.

www.gatwickairport.com

 

[RVJ007]

Perfect thanks