Sudden Increase in Consumption Rate

[Ski Krazy]

My tire pressure is fine.

I understand the effect cold weather can have but it just doesn't make sense with what I've seen. Again, the one week the weather was slightly below freezing, I still saw good consumption then and even for a while after. So if that's how my X handled a week of just below freezing weather, I have tough times believing it's the cause.

Correct me if I'm wrong, but if it we're weather related, shouldn't the change in consumption be in line with the change in weather (i.e. gradual)? Or is it really like at 8 degrees you're fine but at 7 you lose 20-35%?

The weather didn't change significantly in any way when this started happening. Plus, it's even been a little warmer recently going above 10 degrees and the problem persists. Claims of it being weather related just doesn't make sense.

 

[Xenoilphobe]

Headwinds can also have a significant impact on range... also did you leave your parking brake on?
If you are really concerned see if you brakes pads are dragging.... use a FLIR gun to check your rotors or just do the smell test..

 

[BerTX]

My tire pressure is fine.

I understand the effect cold weather can have but it just doesn't make sense with what I've seen. Again, the one week the weather was slightly below freezing, I still saw good consumption then and even for a while after. So if that's how my X handled a week of just below freezing weather, I have tough times believing it's the cause.

Correct me if I'm wrong, but if it we're weather related, shouldn't the change in consumption be in line with the change in weather (i.e. gradual)? Or is it really like at 8 degrees you're fine but at 7 you lose 20-35%?

The weather didn't change significantly in any way when this started happening. Plus, it's even been a little warmer recently going above 10 degrees and the problem persists. Claims of it being weather related just doesn't make sense.

We can't see the issues with your car -- only you can feel those changes.

All we can see and feel are the issues with out own cars. We have all had exactly the same feeling of "this just can't be right" (and some of us who forget have the feeling every fall). We can't say definitively that there is no problem with your car. We can say that we have all thought that there is a problem with our car in the first winter.

As far as the evidence not matching up with cold weather exactly, there are lots of factors and variables that can cause range issues. Maybe you keep the car in a warmer garage in the morning, then by the time you come home in the afternoon, the weather has warmed up, so you aren't really ever dealing with a cold battery when it is "cold" outside. Maybe, as stated by others, there are winds or rains or other factors you don't notice.

If you are feeling there is a problem, then take the car in to have it checked.

 

[rush6410]

I use Teslafi.com to track my drives. One of the data points is avg whr/mi in regards to outside temp in 10 degree increments. My sweet spot is 70 to 80 at 330 whr/mi. As the temp goes down each 10 degree increment, there is a pretty dramatic impact. The lowest I have driven is 40 to 50 degree.

 

[Tyl]

Frigid temps! BEWARE.

I’m an Arizonan, I like warm. 90°

A/C doesn’t impact range to the extent running the heater does.

F R I G I D temps ——you really need 100% more energy to stay toasty warm. Traveling 100 miles?? Have 200 miles of range available or more ..... if you’re from Arizona!!!!!!

 

[Ski Krazy]

Like my original post said, I'm taking it in to get it checked but thought I'd put it out there to see if anyone comes up with a potential explanation that fits. I appreciate the feedback everyone!

Interesting chart on the 10-degree increments. Whether it's a hotter day (for Fall) or colder, my peak efficiency is around 80% and it can get as low as 65%, seemingly regardless of the temperature change.

Update from this morning though. The main screen wouldn't turn on. Tried to reset it but nothing happened. Called Tesla so we'll see what they'll come up with, but add it to the list. My consumption also notably was 100 Wh/Km (wish I could get that on a consistent basis). Not sure if that's the consumption issue I think exists or if it's a result of the main screen not working, thus all of the additional functionality not working too. As I said in my first post, I had this super low consumption rate once before but my screen worked perfectly fine that time, so not sure what it is.

And of course, weather today is no different than yesterday or the day before, etc.

Fun times ahead.

 

[Xenoilphobe]

I really think they should add a propane tank to the car for extreme cold weather regions. Basically anywhere north of the 40th Lat.

 

[jdw]

Thanks Rush6410 - wish I had thought of that. Here's my Teslafi temperature efficiency at some lower temps.

 

[mknox]

We have all had exactly the same feeling of "this just can't be right" (and some of us who forget have the feeling every fall). We can't say definitively that there is no problem with your car. We can say that we have all thought that there is a problem with our car in the first winter.

Yep. I was "fortunate" in that I got my car in the winter months and was used to winter consumption. I couldn't believe how much better it became during my first spring with the car.

Like my original post said, I'm taking it in to get it checked but thought I'd put it out there to see if anyone comes up with a potential explanation that fits. I appreciate the feedback everyone!

FWIW, my consumption has shot up by about 30% and we're not even below freezing yet where I am. As this is my 5th winter with the car, I'm used to it now. The thing with EVs is that the efficiency swings between "good" and "bad" are HUGE compared to an ICE which also is worse in winter weather... just not as much.

 

[aesculus]

This is a great thread.

I am seeing what appears to be battery heating even at 45-50F when starting on a trip unplugged and unpreheated. On a recent trip I started at 90% and traveled to my destination about 100 miles away. Using the dash energy display data I should have arrived with 32% of my battery left, instead I arrived with 26%. The only thing that I can account for that would cause the additional loss is the heating of the battery during this trip.

 

[David99]

The heater uses the exact same amount of energy as the AC. The heater is exactly as efficient as the AC. Resistive heaters are almost 100% efficient. Now why does the heater need to much more energy?

What people forget is the temperature difference. To cool or warm the cabin by 1 degree F you need 65 Watt. If it's 90 outside and you want it to be 70 inside, the temperature difference is 20 degree. You need 20 * 65 Watt = 1300 Watt.

If it's 20 F outside and you want it to by 70 inside the heater has to compensate a 50 degree difference. 50 * 65 = 3250 Watt.

To make things worse, once the battery drops below 50 F, the battery heater turns on and sucks up a lot of energy as well. Colder air is also denser meaning higher air drag. Low temperatures also cause more resistance in other parts. It all adds up.

People always say the heater is less efficient. It is not! it's the combination of all things and mostly the higher temperature difference plus battery heater that causes the high energy usage in cold weather.

 

[hiroshiy]

My tire pressure is fine.

I understand the effect cold weather can have but it just doesn't make sense with what I've seen. Again, the one week the weather was slightly below freezing, I still saw good consumption then and even for a while after. So if that's how my X handled a week of just below freezing weather, I have tough times believing it's the cause.

Correct me if I'm wrong, but if it we're weather related, shouldn't the change in consumption be in line with the change in weather (i.e. gradual)? Or is it really like at 8 degrees you're fine but at 7 you lose 20-35%?

The weather didn't change significantly in any way when this started happening. Plus, it's even been a little warmer recently going above 10 degrees and the problem persists. Claims of it being weather related just doesn't make sense.

I understand your reasoning. It is possible that if the day before was very warm or you traveled for a long distance, or you supercharged your car, the next day the battery still have some heat. Even if the next day is colder, the battery heater may not turn on.
On the other hand if the day before is also cold or you didn't use your car much or it rained so the battery was cold soaked, the next day the battery became very cold and the battery heater could kick in. The only way you know whether the battery heater is on or not is to use logging software like TeslaFi.

 

[BerTX]

The heater uses the exact same amount of energy as the AC. The heater is exactly as efficient as the AC. Resistive heaters are almost 100% efficient. Now why does the heater need to much more energy?

What people forget is the temperature difference. To cool or warm the cabin by 1 degree F you need 65 Watt. If it's 90 outside and you want it to be 70 inside, the temperature difference is 20 degree. You need 20 * 65 Watt = 1300 Watt.

If it's 20 F outside and you want it to by 70 inside the heater has to compensate a 50 degree difference. 50 * 65 = 3250 Watt.

To make things worse, once the battery drops below 50 F, the battery heater turns on and sucks up a lot of energy as well. Colder air is also denser meaning higher air drag. Low temperatures also cause more resistance in other parts. It all adds up.

People always say the heater is less efficient. It is not! it's the combination of all things and mostly the higher temperature difference plus battery heater that causes the high energy usage in cold weather.

Sorry, I have to disagree with your statement that resistance heat is as efficient as a heat pump. A heat pump is much more efficient. You are working under the assumption that because the resistance heater turns all of the energy put into it into heat, that you can't get any more efficient than that. This is incorrect.

The car uses much more energy to heat the interior than it does to cool the interior the same number of degrees.

 

[David99]

Sorry, I have to disagree with your statement that resistance heat is as efficient as a heat pump. A heat pump is much more efficient. You are working under the assumption that because the resistance heater turns all of the energy put into it into heat, that you can't get any more efficient than that. This is incorrect.

I never used the word heat pump, I never made that compairsion. I'm aware that a heat pump would work well!

A resistive heater turns (almost) all energy into heat, thus it is extremely efficient. A heat pump can harness thermal energy from the environment and concentrate it where you want it. It is not a simple energy conversion, it is taking energy from somewhere else. The word 'efficient' refers to how well energy conversions works.

I have said many times that a heat pump would be a great idea in an EV and both Nissan and VW have shows how well it works (up to a certain energy).

The car uses much more energy to heat the interior than it does to cool the interior the same number of degrees.

That is incorrect. Here is a screen shot from EVTripplanner, that has proven to be very accurate in planning routes for EV calculating energy usage. As you can see, the power needed is the same for heating and cooling.

 

[jdchi]

My least favorite thing about my Volt was that it would force the gas engine to run periodically in the winter to heat the battery. When I see my Model X's range getting sucked up by the battery heater, I just tell myself at least I'm not burning gas.

 

[BerTX]

I never used the word heat pump, I never made that compairsion. I'm aware that a heat pump would work well!

A resistive heater turns (almost) all energy into heat, thus it is extremely efficient. A heat pump can harness thermal energy from the environment and concentrate it where you want it. It is not a simple energy conversion, it is taking energy from somewhere else. The word 'efficient' refers to how well energy conversions works.

I have said many times that a heat pump would be a great idea in an EV and both Nissan and VW have shows how well it works (up to a certain energy).



That is incorrect. Here is a screen shot from EVTripplanner, that has proven to be very accurate in planning routes for EV calculating energy usage. As you can see, the power needed is the same for heating and cooling.

View attachment 262682

An air conditioner is a heat pump. It just works in one direction.

 

[David99]

An air conditioner is a heat pump. It just works in one direction.

Oh Ok, now I understand. Yes true if you want to see it that way, the AC is a heat pump. Still the amount of energy to cool or heat the cabin is the exact same. More than double the temperature difference between winter and summer sill causes more than double the energy usage. That plus the battery heater are the main cause for the increased energy usage in winter.

 

[vandacca]

Heat is the lowest form of energy. Not hard to convert energy into heat, in fact, normally one tries not to prevent energy getting converted into heat as a side-reaction (eg. When converting energy into light, sound, vibration, cooling, etc.).

 

[jdw]

It was minus 14C today with a windchill of minus 29 - I hit a new record power usage of 3685 wh/km after being parked outdoors for about 7 hours. (My Tesla outdoor temp reads 2 degrees high).

 

[Krazaak]

Oh Ok, now I understand. Yes true if you want to see it that way, the AC is a heat pump. Still the amount of energy to cool or heat the cabin is the exact same. More than double the temperature difference between winter and summer sill causes more than double the energy usage. That plus the battery heater are the main cause for the increased energy usage in winter.

AC or operating in both modes as a heat pump is much more efficient than resistance heating because it moves existing heat instead of converting electrical energy to heat. So not only is the car overcoming twice the temperature differential, but it's taking roughly twice as much energy for every degree of difference. So you're looking at 4x as much energy to heat the car from 30 to 70 than to cool it from 90 to 70.