Nearly 50% worse than rated: What am I doing wrong?

[camalaio]

Hey folks.

Last week, I drove to another city (Kamloops) and back, twice. It's a trip I've done before and I used to get pretty much exactly the rated range estimate (so around 150Wh/km). However, temps are now around freezing so range is reduced of course. It's mostly highway driving between 95 and 105 km/h, nothing intense.

The first trip we ended up Supercharging so I'm not 100% sure on the numbers, but the Wh/km was the same for the trip.

Second trip I charged to 90% just before leaving, and the car was well preheated (30 mins or so) in a relatively warm garage (15C, about -1C outside). Full with 5 occupants, temp set to auto at 21C, and partial heated seat usage. It sat at the destination for an hour with Sentry on. Didn't preheat the cabin to relocate to downtown. Car sat for two more hours with Sentry on. Preheated just 2 minutes prior to entering the car to drive home.

This 250km round trip used 360km of range (72%). The displayed Wh/km was 198 on both trips, but this indicates actual usage was more around 250+ Wh/km for the trip. The temperature was hovering around freezing for both trips. It's not even that cold and it started with the best possible chance fresh off the wall and pre-warmed, and had 5 heaters in the car in the form of human bodies.

I don't think the 2 minutes I preheated the car for the trip back could possibly burn through that much unaccounted energy, nor do I think Sentry uses that much power. So what am I missing, or what am I doing wrong here? Is this going to get a lot worse at -15C? I heard 50% was absolute worst case scenario, and I don't think that's what these conditions were.

P.S. Yes, I know I heated the air instead of seats. You try to tell family that they don't get to be warm and comfortable all over just because they took the electric car. Having your feet and top of your head be chilly isn't exactly the comfort one expects in a trip with a $75k car.

 

[AdamMacDon]

What I've noticed is the car doesn't seem to log or account for energy burned while parked. Most importantly, this includes "phantom drain" and preheating. Here in mild old Victoria (about 5-10 degrees during the winter) I still see MASSIVE unaccounted for losses. Admittedly I drive pretty aggressively. As you put it, the car costs 70 grand, I didn't buy it to drive like I have an old gen Leaf. But even with my aggressive driving, I find lately with all my short trips around town this winter that nearly 40% of my energy usage is when the car isn't even moving. I rarely use sentry mode, but I DO use the cabin pre-heat feature a lot, and I mean 90% of the time. I usually set it to 20-22 degrees and use the heated seat. Even still, I'll lose about 2-3% charge for the preheating, and then 3-4% for one leg of my daily commute to or from work. Daily I burn about 14% of my charge, or 7kWh, of which almost half is without the car even moving.

The car is so energy efficient, and making heat is frankly not. A combustion engine vehicle has 3-5x more energy potential in the tank than your whole battery does. Also, it is always producing waste heat, so you notice no difference in range/fuel economy using your heater. It simple vents heat into your cabin instead of the atmosphere. The Tesla's heater can consume 6kW of power, which is about the same energy as a standard level 2 charger can pump into your vehicle.

At the end of the day, what is 2 or 3 kWh of electricity compared to your comfort in a $70k car? About 20-30 cents here in BC. We're still laughing every time we pass a gas pump in this province, so I take it as one of the very small knocks we have to deal with as EV owners. Reduced winter range is no shocker, even if the amount that occurs is a bit surprising. It's little consolation, but you seem to be doing better than me, admittedly it probably helps to do long trips instead of short ones where the cabin has to repeatedly be re-heated back to 22 degrees.

 

[AlanSubie4Life]

This 250km round trip used 360km of range (72%). The displayed Wh/km was 198 on both trips, but this indicates actual usage was more around 250+ Wh/km

How do you figure? The discharge “constant” is around 146Wh/rkm.

Lines & Constant Info

So based on your numbers you should have used:

198Wh/km/146Wh/rkm * 250km = 346 rkm

The remaining 14km of use are easily accounted for by Sentry mode (about 5 rated km for 3 hours) and preheating the cabin, which as we all know is not included in the usage meter.

Running the heater full blast is roughly equivalent to driving the car at 45mph. Think about doing that (driving 45mph/72km/h) for 5 minutes - that would use a minimum of 6 rated km. So it is all in the ballpark.

 

[toolman335]

I find it hard to believe that you were at 198 for both trips.
I have seen massive range reduction since the temps dropped, but that is also reflected in what the car says I'm using for power. I've gone from low 200s to almost 300.

 

[SSedan]

As temps have fallen have you maintain d tire pressure?
Tires a little low plus a full load of people would hurt efficiency, and with 5 people you are good NG to have to run heat and defrost to not fog up the windows.

 

[jmaddr]

I find it hard to believe that you were at 198 for both trips.

Are you sure you two are quoting them same numbers? He is from CA and quoting Wh/km. Looks like you are from the US and quoting Wh/mi. Divide 198/.62 and you get 319Wh/mi.

 

[AdamMacDon]

I find it hard to believe that you were at 198 for both trips.
I have seen massive range reduction since the temps dropped, but that is also reflected in what the car says I'm using for power. I've gone from low 200s to almost 300.

We're Canadian so it's Wh per kilometer, multiply that number by 1.6 to get rough Wh per mile.

 

[toolman335]

I thought CA was California lol
I'm still learning the language and math translations in here. Sorry lol.

 

[camalaio]

What I've noticed is the car doesn't seem to log or account for energy burned while parked. Most importantly, this includes "phantom drain" and preheating. Here in mild old Victoria (about 5-10 degrees during the winter) I still see MASSIVE unaccounted for losses. Admittedly I drive pretty aggressively. As you put it, the car costs 70 grand, I didn't buy it to drive like I have an old gen Leaf. But even with my aggressive driving, I find lately with all my short trips around town this winter that nearly 40% of my energy usage is when the car isn't even moving. I rarely use sentry mode, but I DO use the cabin pre-heat feature a lot, and I mean 90% of the time. I usually set it to 20-22 degrees and use the heated seat. Even still, I'll lose about 2-3% charge for the preheating, and then 3-4% for one leg of my daily commute to or from work. Daily I burn about 14% of my charge, or 7kWh, of which almost half is without the car even moving.

The car is so energy efficient, and making heat is frankly not. A combustion engine vehicle has 3-5x more energy potential in the tank than your whole battery does. Also, it is always producing waste heat, so you notice no difference in range/fuel economy using your heater. It simple vents heat into your cabin instead of the atmosphere. The Tesla's heater can consume 6kW of power, which is about the same energy as a standard level 2 charger can pump into your vehicle.

At the end of the day, what is 2 or 3 kWh of electricity compared to your comfort in a $70k car? About 20-30 cents here in BC. We're still laughing every time we pass a gas pump in this province, so I take it as one of the very small knocks we have to deal with as EV owners. Reduced winter range is no shocker, even if the amount that occurs is a bit surprising. It's little consolation, but you seem to be doing better than me, admittedly it probably helps to do long trips instead of short ones where the cabin has to repeatedly be re-heated back to 22 degrees.

I've noticed the same, which is why I pointed out the rather small amount of parked time and minimal preheating. As you pointed out, shorter trips are especially detrimental to "range" in winter since the fixed losses of heating the cabin need to occur regardless of how far you go. At 120km one-way at mostly highway speeds, I had hoped the heating would be less of an impact :S

I do agree with your point of "what's 2 or 3 kWh" because, yeah, that isn't my problem. It's still much cheaper to run than my gas car, if throwing off my lifetime cost calculations a bit more than expected. That trip would've cost me $27 in my Honda Crosstour, but cost me roughly $8 in electricity with the Model 3.

My main concern actually when thinking of writing this thread was "what do I tell locals regarding SR+ vs LR?". This 250km round trip consumed very close to the full capacity of an SR+, and would've required it to charge to 100%. And it's not even that cold! I'm very happy I went with the LR at this point, otherwise this relatively straightforward trip would've needed a detour to the Supercharger for a few minutes. While not a common drive, this is definitely within expectation of what people would want to do with a vehicle around here once in a while.

How do you figure? The discharge “constant” is around 146Wh/rkm.

Lines & Constant Info

So based on your numbers you should have used:

198Wh/km/146Wh/rkm * 250km = 346 rkm

The remaining 14km of use are easily accounted for by Sentry mode (about 5 rated km for 3 hours) and preheating the cabin, which as we all know is not included in the usage meter.

Running the heater full blast is roughly equivalent to driving the car at 45mph. Think about doing that (driving 45mph/72km/h) for 5 minutes - that would use a minimum of 6 rated km. So it is all in the ballpark.

Hoo boy, lemme re-do my late night headache-compromised brain math. I think I figured 72% usage to be 54 kWh (this could be a bit off, I'm sure -- I'm basing it off of 0-100% being exactly 75 kWh). So 54kWh/250km = 216 Wh/km... oh no, that's not even the same number I came up with yesterday! Shame on me. I'm guessing I somehow crossed wires with 250km and 2-something Wh/km, which ended up placing it as 250 Wh/km. Thanks for calling me out on that.

Then again, that's not quite the math I did... I did something more like "100% is 499km of range, so 72% usage is 360 rated km". That's where I figure "nearly 50% worse", because that's 44% worse than rated. And indeed, 150Wh/km * 1.44 == 216Wh/km.

So that shows where I came from. My 250+ Wh/km was a mistake or mistype, apologies. Is the above math somewhat sound? I'm not sure how this relates to the linked "rated" vs "discharge" constants honestly. Bit confusing to me. But perhaps I should have mentioned it's a LR AWD in order to pick out the right numbers.

Now, if somewhat sound, I guess there is a more accurate question to ask:

Is 198 Wh/km reasonable for "slow" highway travel around freezing temps? (not crazy 80mph freeways, nor insanely cold). Even this is 32% worse if using 150 Wh/km (which may be wrong). 32% reduction at freezing temps seems much larger than expected based on what others have said regarding winter on this forum, especially for highway travel which should be best case when heating is involved.

As temps have fallen have you maintain d tire pressure?
Tires a little low plus a full load of people would hurt efficiency, and with 5 people you are good NG to have to run heat and defrost to not fog up the windows.

Yepp, actually inflated just prior to these trips! 42psi cold. It was dropping as low as 37 prior to this, which honestly didn't seem to have a noticeable impact on range by itself (though I lack the measurements and data to properly assert this -- it certainly wasn't the only factor).

Of note and not previously mentioned is that the first trip was just my wife and I. Second trip was 5 people total. Both trips around the same temperature. Both trips got 198 Wh/km on the meter. The extra weight and humidity didn't seem to have a notable impact on efficiency, maybe simply because they also add heat to the interior and it's net negligible.

I thought CA was California lol
I'm still learning the language and math translations in here. Sorry lol.

CA == California is exactly why when I see CA as "Canada", I get either a bit miffed or confused myself two letter country codes are unfortunate in the context of two letter state codes.

I normally try to put the numbers in both freedom units and metric, apologies for skipping that this time around.

 

[toolman335]

Especially since Tesla has a California base and the most Tesla's in the country, the default CA should be Cali! lol

 

[KenC]

Hey folks.

Last week, I drove to another city (Kamloops) and back, twice. It's a trip I've done before and I used to get pretty much exactly the rated range estimate (so around 150Wh/km). However, temps are now around freezing so range is reduced of course. It's mostly highway driving between 95 and 105 km/h, nothing intense.

The first trip we ended up Supercharging so I'm not 100% sure on the numbers, but the Wh/km was the same for the trip.

Second trip I charged to 90% just before leaving, and the car was well preheated (30 mins or so) in a relatively warm garage (15C, about -1C outside). Full with 5 occupants, temp set to auto at 21C, and partial heated seat usage. It sat at the destination for an hour with Sentry on. Didn't preheat the cabin to relocate to downtown. Car sat for two more hours with Sentry on. Preheated just 2 minutes prior to entering the car to drive home.

This 250km round trip used 360km of range (72%). The displayed Wh/km was 198 on both trips, but this indicates actual usage was more around 250+ Wh/km for the trip. The temperature was hovering around freezing for both trips. It's not even that cold and it started with the best possible chance fresh off the wall and pre-warmed, and had 5 heaters in the car in the form of human bodies.

I don't think the 2 minutes I preheated the car for the trip back could possibly burn through that much unaccounted energy, nor do I think Sentry uses that much power. So what am I missing, or what am I doing wrong here? Is this going to get a lot worse at -15C? I heard 50% was absolute worst case scenario, and I don't think that's what these conditions were.

P.S. Yes, I know I heated the air instead of seats. You try to tell family that they don't get to be warm and comfortable all over just because they took the electric car. Having your feet and top of your head be chilly isn't exactly the comfort one expects in a trip with a $75k car.

Full car, temps around freezing, using heat. That will easily knock off 30% of your range, and 198Wh/km vs ~150Wh/km is roughly 30% more. Totally normal. You seem to be missing 20km of range, which was used up during the time the car sat for 3hrs. I would have expected about 3km an hour max, so about 10km used. The diff is still 10km. Could be all the rounding errors, as you're not that far from what might be expected.

 

[AlanSubie4Life]

Is the above math somewhat sound?

In trip meter numbers, the usable capacity of a brand new car is 146Wh/rkm * 500rkm = 72.6kWh, or perhaps as low as 143Wh/rkm * 499rkm = 71.3kWh. The trip meter numbers are not to be confused with battery capacity or available energy, which is different. Trip meter numbers are empirically derived and don't make judgements about what the true available energy is. But they are what they are.

However, no idea whether your car charges to 499rkm at 100% so no way to know whether these would be your numbers.

72% of 71.3kWh over 250km works out to 205Wh/km so it's close but maybe you have 3.5% degradation or so.

Is 198 Wh/km reasonable for "slow" highway travel around freezing temps?

Say steady state heat use is 3kW (this is a pretty reasonable expectation for freezing temps - the peak obviously will be higher but once things come to temperature it might drop to this level):

3kW/100km/hr = 30Wh/km

That would be your adder at that speed. So you would have been getting closer to 168Wh/km if you hadn't been using the heat. Steady state heat demand could have been a bit higher, but this is in the ballpark.

 

[ewoodrick]

Hey folks.

Last week, I drove to another city (Kamloops) and back, twice. It's a trip I've done before and I used to get pretty much exactly the rated range estimate (so around 150Wh/km). However, temps are now around freezing so range is reduced of course. It's mostly highway driving between 95 and 105 km/h, nothing intense.

The first trip we ended up Supercharging so I'm not 100% sure on the numbers, but the Wh/km was the same for the trip.

Second trip I charged to 90% just before leaving, and the car was well preheated (30 mins or so) in a relatively warm garage (15C, about -1C outside). Full with 5 occupants, temp set to auto at 21C, and partial heated seat usage. It sat at the destination for an hour with Sentry on. Didn't preheat the cabin to relocate to downtown. Car sat for two more hours with Sentry on. Preheated just 2 minutes prior to entering the car to drive home.

This 250km round trip used 360km of range (72%). The displayed Wh/km was 198 on both trips, but this indicates actual usage was more around 250+ Wh/km for the trip. The temperature was hovering around freezing for both trips. It's not even that cold and it started with the best possible chance fresh off the wall and pre-warmed, and had 5 heaters in the car in the form of human bodies.

I don't think the 2 minutes I preheated the car for the trip back could possibly burn through that much unaccounted energy, nor do I think Sentry uses that much power. So what am I missing, or what am I doing wrong here? Is this going to get a lot worse at -15C? I heard 50% was absolute worst case scenario, and I don't think that's what these conditions were.

P.S. Yes, I know I heated the air instead of seats. You try to tell family that they don't get to be warm and comfortable all over just because they took the electric car. Having your feet and top of your head be chilly isn't exactly the comfort one expects in a trip with a $75k car.

Sounds like 30% loss in battery capacity. Yep, that'e winter driving.

 

[efusco]

You hadn't put on winter tires, had you? That'll give a range hit too.

 

[camalaio]

This all is very interesting because this puts some Supercharger routes outside the capability of an SR+ in Winter. For example, Kamloops to Whistler. Again, it's not an entirely common route (many will travel via Vancouver instead, hitting two more Superchargers on the way) but certainly one that some people take depending on where they live and their own preferences. There's a 302km gap between these chargers. I see a new SR+ is rated at 402km. This 302km trip may consume an additional 30% just at freezing, which is already going to consume 392 rated kilometres. That's a brutal margin to be playing on within the Supercharger network. If it gets any colder or there are any slowdowns, there is simply no way an SR+ can take this route.

For safety and peace of mind (possible slowdowns, additional usage, etc.) it seems prudent to assume 50% extra usage during true Winter travel, and don't plan to intentionally arrive at chargers with a very low state of charge.

Full car, temps around freezing, using heat. That will easily knock off 30% of your range, and 198Wh/km vs ~150Wh/km is roughly 30% more. Totally normal. You seem to be missing 20km of range, which was used up during the time the car sat for 3hrs. I would have expected about 3km an hour max, so about 10km used. The diff is still 10km. Could be all the rounding errors, as you're not that far from what might be expected.

It's interesting there's so many ways to do the math! I wish I could change my thread title.

This extra difference, rounding errors, whatever we want to call it, is certainly interesting when thinking of available energy in winter. My gas car may have all sorts of downsides, but 50% of a tank when I leave it is still 50% of a tank even the next day, no matter what's going on. When our effective EV range is reduced in winter, these standby losses get a bit annoying (though not absolutely hurtful or concerning in most cases).

In trip meter numbers, the usable capacity of a brand new car is 146Wh/rkm * 500rkm = 72.6kWh, or perhaps as low as 143Wh/rkm * 499rkm = 71.3kWh.

However, no idea whether your car charges to 499rkm at 100% so no way to know whether these would be your numbers.

72% of 71.3kWh over 250km works out to 205Wh/km so it's close but maybe you have 3.5% degradation or so.




Say steady state heat use is 3kW (this is a pretty reasonable expectation for freezing temps):

3kW/100km/hr = 30Wh/km

That would be your adder at that speed. So you would have been getting closer to 168Wh/km if you hadn't been using the heat. Steady state heat demand could have been a bit higher, but this is in the ballpark.

You are a wealth of numerical information. Thank you.

A 90% charge showed 450km, which I believe implies that I still have the full rated range (unless one needs to actually charge to 100% to confirm, which I simply don't do) or at least within a few rated km due to rounding. Actually, this seems impressive given that it just passed 20,000km on the odometer, given the other complaints I've seen on here.

Interesting to put a number to heat at speed, thanks. I suppose additional power may have been dehumidification (as another poster mentioned) requiring the AC, and additionally light use of heated seats. Percent is also a chunky measurement since we don't get decimal values from the display. Anyhow, using your same methodology and my understanding the heater is a maximum of 6kW, I should expect 60Wh/km extra at worst at 100km/h (all else held equal). Throw in dehumidifying, say 3kW for the AC? So 90Wh/km extra total at worst when all else is held equal?

For highway travel assuming a decent pace is kept, this implies no worse than double usage. If you have nasty winter mountain conditions going below 70 km/h in very cold temps requiring a lot of HVAC power, it might be possible to see 300 Wh/km and to expect no more than 250km out of a LR AWD. This is all very good to know before tackling a mountain highway trip!

Sounds like 30% loss in battery capacity. Yep, that'e winter driving.

It's hardly Winter yet!!

You hadn't put on winter tires, had you? That'll give a range hit too.

Y'know... I hadn't considered that! Hah!

Yes, I have squishy Hakkapeliittaa R3 tires on. I had them on when it was still 20C and warmer since it was legally required for highways around here, and I can't say I noticed any large range degradation but there must be a small efficiency loss. On other vehicles where I've gone from all-seasons to the very same winter tire, I haven't noticed any efficiency difference though I know there likely is some.

 

[AlanSubie4Life]

A 90% charge showed 450km, which I believe implies that I still have the full rated range

Yes it does. No need to charge to 100%.

Actually in my prior post I forgot you were talking about your total use (including parked use). So it all makes sense. Your actual Wh/km use was closer to 205-210Wh/km, but driving use was 198Wh/km (similar to the ratio calculated earlier of 346/360). Hard to know the exact numbers without screenshots at various points in the trip, but it all seems to make sense.

Anyhow, using your same methodology and my understanding the heater is a maximum of 6kW, I should expect 60Wh/km extra at worst at 100km/h (all else held equal). Throw in dehumidifying, say 3kW for the AC? So 90Wh/km extra total at worst when all else is held equal?

What the exact maximums are I am not sure (only way I know how to measure is to connect to an 11.5kW charging source and play around while accounting for AC-DC conversion losses). Also remember if you drive slower these numbers get worse. And there are those other factors that come with winter - snow, wind, low tire pressures, etc. Those really drive up your baseline use.

Bottom line: recommend to people to get an LR if they are planning to do long road trips in cold weather.

 

[AdamMacDon]

I've noticed the same, which is why I pointed out the rather small amount of parked time and minimal preheating. As you pointed out, shorter trips are especially detrimental to "range" in winter since the fixed losses of heating the cabin need to occur regardless of how far you go. At 120km one-way at mostly highway speeds, I had hoped the heating would be less of an impact :S

I do agree with your point of "what's 2 or 3 kWh" because, yeah, that isn't my problem. It's still much cheaper to run than my gas car, if throwing off my lifetime cost calculations a bit more than expected. That trip would've cost me $27 in my Honda Crosstour, but cost me roughly $8 in electricity with the Model 3.

My main concern actually when thinking of writing this thread was "what do I tell locals regarding SR+ vs LR?". This 250km round trip consumed very close to the full capacity of an SR+, and would've required it to charge to 100%. And it's not even that cold! I'm very happy I went with the LR at this point, otherwise this relatively straightforward trip would've needed a detour to the Supercharger for a few minutes. While not a common drive, this is definitely within expectation of what people would want to do with a vehicle around here once in a while.

Just maintaining that cabin temperature can take a shocking amount of energy. The other day we had a cold snap down to about 5 degrees and I used the "leave climate control on" option while I ran into the grocery store to get a few quick items for dinner. I shop crazy fast and I was done in 10 minutes or so. I do this in the summer as I find maintaining the cabin temp for 5-10 minutes is more efficient than cooling it down again. Not the case in the winter, I lost 3% in 10 or so minutes. I can only imagine when driving with the cold wind ripping over that glass roof and sucking heat away.

I have an SR+ and I'd say that it's more than sufficient for long trips, I just hit Vegas and back in it. The bigger issue in BC (and most of Canada) is lack of charging infrastructure. Petro Canada is gonna have some EV charging stations soon but those are non Tesla options so we can't use them, unless you have a $600 adapter that charges at a painful 50KW max. Superchargers are really far spread out. Down in the western US states I never worried about range at all, as I was surrounded by superchargers. 500km vs 400km isn't really a big difference for most people if the infrastructure was decent. For gas cars no one would worry about a 100km range difference in gas tanks enough to sway a purchase. Hopefully in the next few years 3rd party CCS chargers start sprouting up and Tesla offers an adapter for it like they have in Europe.

 

[AlanSubie4Life]

You are a wealth of numerical information. Thank you.

Just maintaining that cabin temperature can take a shocking amount of energy.

Just as a datapoint, steady state cabin temperature of 74 degrees, outside temp of 49 degrees, pulls 2.2kW steady state from a Chargepoint. There are conversion losses there, so that's about 2kW steady state for a temperature differential of 25 degrees. I think that to first order only the difference in temperature matters, though there may be other non-ideal effects that come into play. Newton's law of cooling says that the rate of heat loss is proportional to the temperature difference, so if it's freezing outside and you want it to be 70 degrees in the cabin, it's going to be closer to 3kW.

As a rule of thumb, seems like it's about 1kW per 10 degrees F of heat difference, I suppose. Haven't really thought about this. Would imply that if it is -40F outside, the heater might have a hard time keeping up...which seems like it might not be correct. People in cold climates will let us know, I guess.