Cold weather battery range loss: Past experiences

Doug_G said:

Current Odometer: 17,000 km

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Lightweight! I have 22,344 km on the car and picked mine up 3+ months after you :biggrin:

Doug_G said:

Vehicle: 2012 Tesla Model S P85
Range in Summer: 424 km (Rated Range - and also quite achievable at 90 - 95 kph) (265 miles)
Range in Winter: 380 km at 0 degrees C, 330 km at -20 degrees C. (238 miles @ 32F, 206 miles @ -4F)
Location: Ottawa, Ontario
Current Odometer: 17,000 km

(Winter range assumes pack preheated. Mileage may vary due to road conditions!)

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My experience is very consistent with what Doug stated, doing winter driving in Colorado. Much of that loss at low temps is for cabin heating and battery pack heating. Also, I have found losses of about 10 miles (16 km) or more in rated range warming up the cabin and battery from a cold soak at 0 F., -18 C.

If you have shore power, you can get rid of a lot of this by doing the last hour of charge just before departure and turning on the cabin heater with the App. This was quite effective when I left Taos last winter with my MS outside on shore power.

Here is a nice warning that you get at low temps and low SOC; I had about 28 rated miles left in the battery then and the temp was about 32 F., 0 C.:

Cottonwood said:

Here is a nice warning that you get at low temps and low SOC; I had about 28 rated miles left in the battery then and the temp was about 32 F., 0 C.:

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That's balmy weather for much of the winter here in Ontario. It's kind of a scary message if you're out and can't necessarily charge "now".

I have been watching this very closely to try and determine my true range for trip planning in the cold weather. I have found the following in the winter:
Each drive started with a cold car and a cold battery will cost you 10 miles of range off the top, really quickly. The car is heating the battery and the cabin and it it costs you energy. You will see this in the restricted regen rates/bars and restricted max acceleration. Once the battery warms up, the bars go away. All your cabin heat comes from the battery pack unless you are plugged in and cabin heat takes an awful lot of energy out of your battery range. So if I do 5 short trips over the whole day, and my car is parked outside and gets cold in between, I see a big hit in my range for that day. Because of the range loss, and it's consistent, I don't believe there is any useful gain from the motor coolant, which I have seen some people post about.
if I make one longer trip, I see the 10 mile hit initially but then the usage gets more normal. I don't see any usage spikes from pack heating but I still get a 25% reduction in range from driving in cold weather. So on days with a lot of short trips I see a significant hit, I've even seen a day with lots of short trips cost me 2x the rated range.
It took me a while to figure this out but I get very consistent estimates for myself now. Hope this helps others.

It will be my first winter and was surprised at the energy use, I do keep the car on shore power and have visibletesla set to prewarm the car (boy I do miss heated steering wheels however). But I am getting 300w/km now vs 240 when heading out in the morning. So that is a 20% loss and it is only 0 C. Side not that I noticed when the heater is on in the car, it is drawing 20amps from shore power according to the dash (car was not charging but was showing drawing 19-20amps of the available 80amp hpwc). I also try and have charging completed by 6am, but the pack still has the regen limit.

SlyWombat said:

It will be my first winter and was surprised at the energy use, I do keep the car on shore power and have visibletesla set to prewarm the car (boy I do miss heated steering wheels however). But I am getting 300w/km now vs 240 when heading out in the morning. So that is a 20% loss and it is only 0 C. Side not that I noticed when the heater is on in the car, it is drawing 20amps from shore power according to the dash (car was not charging but was showing drawing 19-20amps of the available 80amp hpwc). I also try and have charging completed by 6am, but the pack still has the regen limit.

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This is my first winter with my model S also. I've noticed the same things as you. I time my charging to finish when I am ready to leave, and preheat the cabin using shore power for 5-10 minutes. But the regen limit still shows at 30. I suppose if I heated the cabin longer, the regen line would go away.
Use to get 177w/km, and am now averaging 230 for the month of November.

My dilemma is when I leave work, and am not plugged in. Is it better to preheat the car using the battery (I noticed a huge energy usage when doing this), or drive the car without preheating and having no regen until it warms up after 10-15 minutes of driving.

mibaro2 said:

My dilemma is when I leave work, and am not plugged in. Is it better to preheat the car using the battery (I noticed a huge energy usage when doing this), or drive the car without preheating and having no regen until it warms up after 10-15 minutes of driving.

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I think this will depend very much on your definition of better. I suspect that the second course of action will consume less energy.

However, to my mind the first course is very much better - a nice warm car to drive in, and more predictable driving experience. EVs are so energy efficient to begin with that I don't feel like pinching the pennies is worth it for the trivial additional savings, assuming you aren't near the edge of the car's range.
Walter

Saghost said:

I think this will depend very much on your definition of better. I suspect that the second course of action will consume less energy.

However, to my mind the first course is very much better - a nice warm car to drive in, and more predictable driving experience. EVs are so energy efficient to begin with that I don't feel like pinching the pennies is worth it for the trivial additional savings, assuming you aren't near the edge of the car's range.
Walter

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Sounds like smart advice. Yes, a warm car is much nicer to drive in. I guess I have always gotten use to focusing on wh/km.
I'll focus on comfort first.

mibaro2 said:

Sounds like smart advice. Yes, a warm car is much nicer to drive in. I guess I have always gotten use to focusing on wh/km.
I'll focus on comfort first.

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Your life, your money, your choice, always.

I'm just trying to put it in perspective - you might save ten cents a day or so by not preheating. How much do you spend on coffee, again?

mibaro2 said:

Sounds like smart advice. Yes, a warm car is much nicer to drive in. I guess I have always gotten use to focusing on wh/km.
I'll focus on comfort first.

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My first year driving in cold weather, and not impressed with the engineering. I leave work and yes I have the car preheated, but regen is still at close to zero (and this is only at -5C). I drive one foot, so this difference in driving is annoying, I dont care about the extra 50km that it might take to warm up the packs at the same time as the cabin, I want consistent driving. There is no reason that regen could not be directed instead to warming the pack instead of just being ignored and coasting. Give me the option, and oh yeah, give me a heated steering wheel!

SlyWombat said:

My first year driving in cold weather, and not impressed with the engineering. I leave work and yes I have the car preheated, but regen is still at close to zero (and this is only at -5C). I drive one foot, so this difference in driving is annoying, I dont care about the extra 50km that it might take to warm up the packs at the same time as the cabin, I want consistent driving. There is no reason that regen could not be directed instead to warming the pack instead of just being ignored and coasting. Give me the option, and oh yeah, give me a heated steering wheel!

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In my experience the key factor is how long you preheat before you leave work.

Last winter when it was significantly colder (-20C or less) I had to remind myself to think ahead and start pre-warming for at least 30 minutes (or more) prior to my departure. 10 minutes will not cut it.

Regen limit was much lower when starting my drive home, and as a bonus the car essentially defrosted itself, just had to wipe the snow off the roof and hood.

I also found that using range mode (not to be confused with a range charge) reduced the power use by the battery warmer, such that I had limited regen for my entire drive home. Unless you need every km from your daily charge, IMHO it is not worth it for day to day use in winter.

Otherwise, aside from some steering and suspension stiffness in extreme colds, the car performed amazingly well with proper winter tires (I have Hakka 7s).

Heated steering would be nice, but this is also mitigated by pre-warming longer.

Jeeps17 said:

Regen limit was much lower when starting my drive home...

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Much lower? It is turned off, the orange line was just a hair off of zero for the first km, I like the regen, not just for energy recovery, but my brake pads will wear 50% more over the winter instead of summer, so instead of coasting, it would be nice if it spun the energy to the heater instead of to charging. I have limited regen almost all the way home, 30km (90% on 407).

SlyWombat said:

it would be nice if it spun the energy to the heater instead of to charging.

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There are two ways that the pack heats up. One is directly through the cooling fluid as a by-product of regeneration (because regen isn't 100% efficient), the other is from electric heating, which comes from the battery. So it's doing what you want right now. It just takes a bit of time if you don't pre-heat with range mode off.

jerry33 said:

There are two ways that the pack heats up. One is directly through the cooling fluid as a by-product of regeneration (because regen isn't 100% efficient), the other is from electric heating, which comes from the battery. So it's doing what you want right now. It just takes a bit of time if you don't pre-heat with range mode off.

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I'm not entirely sure what you mean by "through the cooling fluid as a by-product of regeneration" but the pack cooling fluid loop is coupled in to the drive unit cooling loop so that any excess heat that's generated during normal operation, not just regen, can be dumped in to the pack.

Where regen specifically provides additional heating potential is that the electrical current being provided to the cells causes the, to get warmer during regen... but that's because li-ion chemistry is such that they build more heat when drawing current as they charge than they do when providing current for normal driving. But it this case the coolant fluid has nothing to do with it...

scaesare said:

I'm not entirely sure what you mean by "through the cooling fluid as a by-product of regeneration" but the pack cooling fluid loop is coupled in to the drive unit cooling loop so that any excess heat that's generated during normal operation, not just regen, can be dumped in to the pack..

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That was what I meant, but I limited it to regeneration.

scaesare said:

Where regen specifically provides additional heating potential is that the electrical current being provided to the cells causes the, to get warmer during regen... but that's because li-ion chemistry is such that they build more heat when drawing current as they charge than they do when providing current for normal driving. But it this case the coolant fluid has nothing to do with it...

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Correct. That's why there are two ways to heat the pack.

jerry33 said:

Correct. That's why there are two ways to heat the pack.

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That doesn't sound like what you described... you said, "the other is from electric heating, which comes from the battery".


In order to be clear for those unfamiliar with the system: the electric heating coming FROM the battery is when the battery provides electrical power to resistive heating elements that can warm the fluid circulating within the pack. That's NOT the same as the heating effect when the battery is being charged. that energy comes FROM the drive motor/inverter during regen, not the pack.

To be clear, there are actually 3 ways the pack can be warmed:

1) Waste heat from the drive unit
2) Internal heat gernerated within the cells when being charged by regen
3) Electrical pack heaters within the pack thermal management system

-sc

SlyWombat said:

Much lower? It is turned off, the orange line was just a hair off of zero for the first km, I like the regen, not just for energy recovery, but my brake pads will wear 50% more over the winter instead of summer, so instead of coasting, it would be nice if it spun the energy to the heater instead of to charging. I have limited regen almost all the way home, 30km (90% on 407).

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With the temperatures we had last week, I was at zero regen if I did not heat the cabin for more than 5 minutes. Heating it at 26 degrees for 15-20 minutes put the regen line down to 30. What temperature were you preheating the car to? Initially 26 seemed high to me, but Cottonwood and Stevezzz suggested that temperature.
OTOH, if the battery pack doesn't preheat properly, I wonder if the SC needs to look at it.

scaesare said:

That doesn't sound like what you described... you said, "the other is from electric heating, which comes from the battery".


In order to be clear for those unfamiliar with the system: the electric heating coming FROM the battery is when the battery provides electrical power to resistive heating elements that can warm the fluid circulating within the pack. That's NOT the same as the heating effect when the battery is being charged. that energy comes FROM the drive motor/inverter during regen, not that pack.

To be clear, there are actually 3 ways the pack can be warmed:

1) Wast heat from the drive unit
2) Internal heat gernerate within the cells when being charged by regen
3) Electrical pack heaters within the pack thermal management system

-sc

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My lousy description ability, and you're right--there are three.

- - - Updated - - -

mibaro2 said:

With the temperatures we had last week, I was at zero regen if I did not heat the cabin for more than 5 minutes. Heating it at 26 degrees for 15-20 minutes put the regen line down to 30. What temperature were you preheating the car to? Initially 26 seemed high to me, but Cottonwood and Stevezzz suggested that temperature.
OTOH, if the battery pack doesn't preheat properly, I wonder if the SC needs to look at it.

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26 isn't high for preheating--if it's very cold (-18 C) you might consider setting it even higher (e.g. HI). Just over 30 is the normal regen line value for me when I pre-heat not in range mode. (Slightly under 30 is what I get if I forget to turn off range mode.) It takes me about ten miles to get rid of the line when driving in range mode (ambient -4 to -8), and is mainly non-noticable because the first ten miles are mostly 40-45 mph speed limit, by the time I get to a higher speed limit (15 miles) the line has been gone for some time and there is no regen limitation.