Range-Loss Related to Heat?

[dansev]

My 2019 Dual Motor M3 never had the 310 range I was promised. I started at about 305. It dropped to about 284 (derived from the Stats app) by 60k miles. This seems like a standard drop, from what I have read. But just in the last two months, it went from 283-286 or so, down to 274 almost overnight. Do any of you battery experts think this was actual degradation or reflective of the tremendous heat we have had this summer, and a sudden change in driving habbits? I'm in Boston and since July 1, most of my driving since this started was 120 mile trips out to Cape Cod (and back), which I do a couple times per week. When I'm not driving, the car is unavoidably baking in the very hot sun.

In the end, it is what it is, and I don't get too worked up over the range, but this has kind of been bugging me seeing it drop so quickly from ~284 to ~274.

Other info: I rarely supercharge (maybe 12 times since buying the car.) I use winter tires when the temps drop below 45, which were swapped out in April for a new set of MXM4s. I don't drive especially aggressively (but, hey, sometimes we all step on the go pedal!) I used to charge immediately arriving at home to 80% until about 40,000 miles, when I read the long battery thread and started to realize that less is better. Since 40k miles, I now charge beginning at 5am. I charge to 70% when I have a typical work day, 80-88% infrequently when taking longer work drives. I rarely charge over 90%, but maybe a dozen times to 98% for road trips. Might have charged to 100% a couple of times. Never been below 6%. Typically I try to keep it around 58% when the car is going to be sitting around for a few days (with local errands, etc.)

Thanks for any input!

 

[KenC]

You seem to be doing what you can, so I'm not sure what the recent 10mile drop could be. Though, you seem to have been in the 284 mile range for a good long time. Just realize that Stats used a temp-dependent SOC api until about Jan 2021, so your early Battery Health data reflected a combo of estimated range AND temperature effects. After, it used the other SOC api that didn't show temperature effects, so a better estimate of battery health. You can tell, because the old SOC api would show low battery health on blue snowflake days, and now it doesn't. Actually, I forgot, but my avatar shows some outliers, and those were blue snowflake days, before the SOC api changed.

 

[Candleflame]

My 2019 Dual Motor M3 never had the 310 range I was promised. I started at about 305. It dropped to about 284 (derived from the Stats app) by 60k miles. This seems like a standard drop, from what I have read. But just in the last two months, it went from 283-286 or so, down to 274 almost overnight. Do any of you battery experts think this was actual degradation or reflective of the tremendous heat we have had this summer, and a sudden change in driving habbits? I'm in Boston and since July 1, most of my driving since this started was 120 mile trips out to Cape Cod (and back), which I do a couple times per week. When I'm not driving, the car is unavoidably baking in the very hot sun.

In the end, it is what it is, and I don't get too worked up over the range, but this has kind of been bugging me seeing it drop so quickly from ~284 to ~274.

Other info: I rarely supercharge (maybe 12 times since buying the car.) I use winter tires when the temps drop below 45, which were swapped out in April for a new set of MXM4s. I don't drive especially aggressively (but, hey, sometimes we all step on the go pedal!) I used to charge immediately arriving at home to 80% until about 40,000 miles, when I read the long battery thread and started to realize that less is better. Since 40k miles, I now charge beginning at 5am. I charge to 70% when I have a typical work day, 80-88% infrequently when taking longer work drives. I rarely charge over 90%, but maybe a dozen times to 98% for road trips. Might have charged to 100% a couple of times. Never been below 6%. Typically I try to keep it around 58% when the car is going to be sitting around for a few days (with local errands, etc.)

Thanks for any input!

The battery degradation doesnt gradually go down because the car only knows how degraded the battery is from multiple voltage readings while driving, distance and voltage and resting voltages. The car has an internal voltage table which corresponds to %SOC. Thats why when the car rests you sometimes gain 1-5% SOC (depending how off the BMS is). When I leave my car sit at 50% and cycle between 40 and 55% for a month on my first charge to >70% I often gain 5% after resting. Very rarely I lose range - if you lose 1-2% thats a good sign that the car has underread the available capacity so means you have more rated kms than the car thinks you have.

As such the BMS will leave a nice safety margin (4.5% on the bottom of the battery with the assumption that you dont degrade 4.5% in like... 6 months or whatever). When it has enough OVC readings and drive readings it will reduce the max rated range/max kwh available from the battery.

So going from 273 to 274 overnight is exactly what should happen. A gradual reduction by i.e. 1 mile/day would be highly unusual and is more suggestive of something else than degradation. Temperature does slightly affect BMS readings because the battery will have a higher voltage with warmer temperatures and also release a bit more energy so the BMS thinks the car holds a bit more charge - which is why rated kms sometimes go a bit up in summer.

Best thing you can do to prolong battery life in the most non-annoying way possible is to limit max charge for daily driving (70 or 80% is pretty good) and if your car sits a lot and doesnt get driven much to limit max SOC <55% true SOC.

Also you get slightly better BMS readings by not plugging the car in straight away and charging it - best thing is to let it automatically charge over night as opposed to straight away. Helps to get a few low SOC voltage readings.

 

[DrChaos]

The sudden drop is probably a BMS calibration issue. But yes, heat will degrade batteries even when not in use, aka "calendar aging" so some of the drop is real.

If you can, park in cooler locations and keep the average state of charge as low as feasible. High heat multiplied by high state of charge accelerates degradation.

I think you're doing well on the battery charging schedule. But you could probably keep the state of charge even lower. Do you need to use most of the 70% for an average work day? For calendar aging, it's average daily habits that matter more than occasional excursions. A once in a while supercharger is less important especially if you start using that charge immediately. Can you keep the car lower than 50% for longer?

What I do: I set my daily charge limit to 50% (when that will be enough) and set my charging schedule for both set departure time and to charge only in super off-peak hours (midnight to 6 am). The result is that the car wakes up and charges enough to finish by 6AM so it spent more time at a lower state of charge.

 

[JackLuminous]

I don't know what happened but in the last couple weeks or so, there seem to be serious battery range loss. We always charge to 80% at home and lately it seems to really be going down quickly and the car is barely 1 year old. Just now, from doing errands (local groceries, shopping, post office, etc.) that is mostly local roads and only 1 freeway, the car is already down to 60% from an 80% charge this morning. Usually, after those same trips it would be about 72% or so.

Also, lately when my wife comes from work (it's really her car) she's getting home with ~58%, This week it's almost 50%. Previously, (using last summer and fall for comparision) those same drives into work and back home would mean she'd get home with around 65% or so (going from memory).

This doesn't seem right to me. Could this be heat-related? Dunno. I noticed noticed when the AC is on, the car now has a high-pitched fan/motor noise from the front end that was not there until recently. The whole HVAC seems tremendously loud.

 

[Candleflame]

I don't know what happened but in the last couple weeks or so, there seem to be serious battery range loss. We always charge to 80% at home and lately it seems to really be going down quickly and the car is barely 1 year old. Just now, from doing errands (local groceries, shopping, post office, etc.) that is mostly local roads and only 1 freeway, the car is already down to 60% from an 80% charge this morning. Usually, after those same trips it would be about 72% or so.

Also, lately when my wife comes from work (it's really her car) she's getting home with ~58%, This week it's almost 50%. Previously, (using last summer and fall for comparision) those same drives into work and back home would mean she'd get home with around 65% or so (going from memory).

This doesn't seem right to me. Could this be heat-related? Dunno. I noticed noticed when the AC is on, the car now has a high-pitched fan/motor noise from the front end that was not there until recently. The whole HVAC seems tremendously loud.

AC and heating makes a HUGE difference for short trips. When I lived in the tropics 400w/km was normal on short trips. Then there might be other things like overheat protection etc.
Just see how much you charge to when you charge to 80% and post that here and what your kms are.

 

[Flybyglass]

Check tire pressures to spec. I add 2psi all around.

 

[White Shadow]

Looking forward to the day that nobody has to worry about head/cold/charge rate/max charge level etc... and you just plug in every night and charge to 100%.

Worrying about battery degredation all the time would just annoy me enough to buy a tanker full of gas

Battery technolgy just can't advance fast enough.

 

[Candleflame]

Check tire pressures to spec. I add 2psi all around.

Ah the good old 50 psi on long roadtrips.

 

[Regaj]

My 2019 Dual Motor M3 never had the 310 range I was promised. I started at about 305. It dropped to about 284 (derived from the Stats app) by 60k miles. This seems like a standard drop, from what I have read. But just in the last two months, it went from 283-286 or so, down to 274 almost overnight. Do any of you battery experts think this was actual degradation or reflective of the tremendous heat we have had this summer, and a sudden change in driving habbits? I'm in Boston and since July 1, most of my driving since this started was 120 mile trips out to Cape Cod (and back), which I do a couple times per week. When I'm not driving, the car is unavoidably baking in the very hot sun.

I don't know what happened but in the last couple weeks or so, there seem to be serious battery range loss. We always charge to 80% at home and lately it seems to really be going down quickly and the car is barely 1 year old. Just now, from doing errands (local groceries, shopping, post office, etc.) that is mostly local roads and only 1 freeway, the car is already down to 60% from an 80% charge this morning. Usually, after those same trips it would be about 72% or so.

Also, lately when my wife comes from work (it's really her car) she's getting home with ~58%, This week it's almost 50%. Previously, (using last summer and fall for comparision) those same drives into work and back home would mean she'd get home with around 65% or so (going from memory).

This doesn't seem right to me. Could this be heat-related?

Heat is probably the worst thing there is when it comes to accelerating degradation of Lithium-ion batteries. But that's a long-term factor and isn't going to manifest itself over a very short span of time.

@dansev, it's much more likely that your change in driving pattern this summer is part and parcel of what's going on. Paying attention to the Energy and Trip apps should tell you what your Wh/Mile is, and has been... and will likely give you some insight into what's going on.

 

[Kimmi]

2021 LR AWD with 16K miles. Glad I purchased the LR! Trip to Sequoia national Park last week. West Covina California to Traver supercharger was 210 miles. I started at 100% and I arrived with 1%? 104 to 106° outside temperature driving speed limit +5 miles an hour which is averaging between 70 and 75. Cold tire pressures were 44 psi.
While I am having my wine Tesla also needs to put in a supercharger in Visalia California. To get to the park you need to drive 20 miles out of your way to top up and then after you come down out of the mountains you need to drive 20 miles out of your way to top up to get home. Coming down the mountain was cool though started at 22% and by the time I got to the bottom of the mountain I had 32%.

 

[jackmott]

Its easy to get worried about hot days and range when you are doing errands around town. Lots of overhead cooling the cabin off repeatedly, and cooling batteries after you park over and over. On road trips though I find range to be unaffected by hot weather. The AC gets the cabin to temps once then holds it, and the reduce air density of hot air on the highway tends to make up for that AC use. You also don't need to precondition much between superchargers which saves energy.

 

[KenC]

2021 LR AWD with 16K miles. Glad I purchased the LR! Trip to Sequoia national Park last week. West Covina California to Traver supercharger was 210 miles. I started at 100% and I arrived with 1%? 104 to 106° outside temperature driving speed limit +5 miles an hour which is averaging between 70 and 75. Cold tire pressures were 44 psi.
While I am having my wine Tesla also needs to put in a supercharger in Visalia California. To get to the park you need to drive 20 miles out of your way to top up and then after you come down out of the mountains you need to drive 20 miles out of your way to top up to get home. Coming down the mountain was cool though started at 22% and by the time I got to the bottom of the mountain I had 32%.

So, why didn't you add a little juice in Bakersfield, on your way to the Travers SC, rather than almost run out? Or was the mileage gap so big between the two, that you didn't realize how marginal you were until you were well past Bakersfield?

Here's another thought, did you consider charging up to 100% in Bakersfield, and then drive to SNP and back to Bakersfield? Would that have worked?

 

[dmurphy]

Looking forward to the day that nobody has to worry about head/cold/charge rate/max charge level etc... and you just plug in every night and charge to 100%.

Worrying about battery degredation all the time would just annoy me enough to buy a tanker full of gas

Battery technolgy just can't advance fast enough.

Buy a Standard Range car with the LFP battery and that's exactly the scenario.

In my case, since I have a Long Range, it's 90% set-it-and-forget-it.

I know there's plenty of folks here who can dive into excruciating detail about why that's sub-optimal, but in my case... the ease of use makes up for the potential downsides.

Still holding my own quite well - almost 50k miles and I'm displaying a max range of 282 miles... was 309 when new. I'm sure I can do whatever tips and tricks to increase that a few points if I really cared... but I don't. The real difference between 282 and 309? Nothing. There's no scenario where it's the difference between making it somewhere and being stranded. There's also no scenario where it makes the difference between driving or a quick Supercharging stop. Either I'm stopping anyway, or I'm not.

A 27 mile gain is, what, 1-2 minutes at a Supercharger? About 45 seconds on a 250kW station.

 

[Kimmi]

This was my third time to the Traver SC and never used this much battery. Bakersfield too far away to get to the park and back. 1000+ kWh going up the mountain. 100% charge shows 328 mile range. Does not say on what planet though?

So, why didn't you add a little juice in Bakersfield, on your way to the Travers SC, rather than almost run out? Or was the mileage gap so big between the two, that you didn't realize how marginal you were until you were well past Bakersfield?

Here's another thought, did you consider charging up to 100% in Bakersfield, and then drive to SNP and back to Bakersfield? Would that have worked?

I

 

[AAKEE]

- if you lose 1-2% thats a good sign that the car has underread the available capacity so means you have more rated kms than the car thinks you have.

Its the other way around.

If the battery/BMS increase the SOC when the OVC reading is present after a drive, the BMS has an underestimate of the capacity.

For example, BMS thinks the capacity is 80kWh, and the SOC is 100% fully charged. Driving and using 40kWh give the BMS the infor that the SOC should be 50% (disregard the buffer etc for this). So SOC on the screen is 50%. After parking and the OVC reading is available, the BMS finds that the voltage present shows 52% SOC. SOC is adjusted to52%. 40kWh was still used, but 40kWh is then not 50% used but 48%.
The real capacity should be around 40/0.48 = 83.3kWh.

I had my NFP rocket down from 80.5-81kWh to 77kWh a couple of months back. Happened quite quick and there was a software update just before the drop.
Before this the SOC most often did not change after a drive when parking and a OVC reading was available. If it did, the SOC was adjusted down 1% or SO. Using SMT I could see that the SOC often reduced a little, but not enough to kick a % on the screen.

After the drop, the car always regain a percent and longer drives means 2% or so increase. This was a sign of underestimation and I recently drove 100-0.41%, and during this drive i used 75.15kWh with 3.8kWh remanining, and the SOC increased after parking the car (=still slightly more onboard then the BMS thought).

So the BMS underestimated the capacity about 2kWh Which caused the SOLC to rise after each sleep following a (long enough) drive.


It looks like this, and even short drive like today (not the picture) means a increased SOLC after the sleep.

If your car increase the SOC after sleeps more on a regular basis then it is probable that your BMS underestimates the capacity.

 

[N54TT]

Buy a Standard Range car with the LFP battery and that's exactly the scenario.

In my case, since I have a Long Range, it's 90% set-it-and-forget-it.

I know there's plenty of folks here who can dive into excruciating detail about why that's sub-optimal, but in my case... the ease of use makes up for the potential downsides.

Still holding my own quite well - almost 50k miles and I'm displaying a max range of 282 miles... was 309 when new. I'm sure I can do whatever tips and tricks to increase that a few points if I really cared... but I don't. The real difference between 282 and 309? Nothing. There's no scenario where it's the difference between making it somewhere and being stranded. There's also no scenario where it makes the difference between driving or a quick Supercharging stop. Either I'm stopping anyway, or I'm not.

A 27 mile gain is, what, 1-2 minutes at a Supercharger? About 45 seconds on a 250kW station.

I‘m of the same sorta school of thought. But I just like the power and can feel the difference at lower SOC’s. I’m at 56k and my max range suddenly dropped to mid 260’s but is currently trending back to mid 270’s. Either way it hasn't changed my daily driving nor the way I road-trip, compared to when it was new and had 310. If I get to the point where I need to seek warranty for battery degradation, so be it. I paid for the performance model 3 and want the performance lol. Until then it’s 90% set it and forget it.

 

[White Shadow]

Buy a Standard Range car with the LFP battery and that's exactly the scenario.

In my case, since I have a Long Range, it's 90% set-it-and-forget-it.

I know there's plenty of folks here who can dive into excruciating detail about why that's sub-optimal, but in my case... the ease of use makes up for the potential downsides.

Still holding my own quite well - almost 50k miles and I'm displaying a max range of 282 miles... was 309 when new. I'm sure I can do whatever tips and tricks to increase that a few points if I really cared... but I don't. The real difference between 282 and 309? Nothing. There's no scenario where it's the difference between making it somewhere and being stranded. There's also no scenario where it makes the difference between driving or a quick Supercharging stop. Either I'm stopping anyway, or I'm not.

A 27 mile gain is, what, 1-2 minutes at a Supercharger? About 45 seconds on a 250kW station.

It's not that simple. The "charge to 100%" is just one part of my complaint. The rest is losing range due to the host of other causes (temperature, headwind, running heat in winter or A/C in summer, etc...) and the stadard range car is already stuck with less range than the other models. But don't mind me....I'm just complaining for the sake of complaining. It just seems that going electric today means that you have to constantly take all of this into account unless you have a short commute and are only doing the back-and-forth to work thing. Road trips take much more consideration. You have to plan your trip from supercharger to supercharger. It will be nice when we get passed that point and a road trip in an EV will be more like a road trip in an ICE vehicle.

 

[dmurphy]

It's not that simple. The "charge to 100%" is just one part of my complaint. The rest is losing range due to the host of other causes (temperature, headwind, running heat in winter or A/C in summer, etc...) and the stadard range car is already stuck with less range than the other models. But don't mind me....I'm just complaining for the sake of complaining. It just seems that going electric today means that you have to constantly take all of this into account unless you have a short commute and are only doing the back-and-forth to work thing. Road trips take much more consideration. You have to plan your trip from supercharger to supercharger. It will be nice when we get passed that point and a road trip in an EV will be more like a road trip in an ICE vehicle.

So what I'll say is that, for me (and well, for you, really, being in the same state and all ....) -- unless crossing state borders, it doesn't matter. My daily charge is plenty to get anywhere I need in NJ.

As for road trips, little planning if any is necessary. The car's in-dash navigation has improved so much as far as range accuracy, that I let it handle things. Even on my road trip to/from Florida - towing a 5000lb camper - where Model X was drawing from 2-3x its usual wattage .... it still kept up fine, and no planning was needed.

I feel as if we're there with Tesla... other manufacturers, not so much ... but Superchargers are *so* prevalent that I haven't run into any situation -- even as far west as Wyoming -- where I've had to worry about it.

 

[KenC]

It's not that simple. The "charge to 100%" is just one part of my complaint. The rest is losing range due to the host of other causes (temperature, headwind, running heat in winter or A/C in summer, etc...) and the stadard range car is already stuck with less range than the other models. But don't mind me....I'm just complaining for the sake of complaining. It just seems that going electric today means that you have to constantly take all of this into account unless you have a short commute and are only doing the back-and-forth to work thing. Road trips take much more consideration. You have to plan your trip from supercharger to supercharger. It will be nice when we get passed that point and a road trip in an EV will be more like a road trip in an ICE vehicle.

Haha, maybe the EV transition is easier for those of us, like me, who did a lot of trip planning when I had a gas vehicle?

As to some of the specifics that you mention, I sometimes wonder if Tesla should have kept their original charge strategy with the Model S, where 90% was considered a full charge, and that there was an extra setting for Trips. Psychologically, letting owners set their car for full, seems to make everyone happier, even if it can be filled a little more.

How many times have we seen people fill their gas vehicle to where the pump handle clicks off; then they pump until it clicks a couple times more? At gas stations with attendants, I remember seeing attendants add a full gallon after the first click off. Of course, now we know that filling too full can damage the vapor thingy. Still, people do it, because they like to "fill" their cars.

As for some of the other things, strangely enough, ICE vehicles may also be impacted. Headwinds have exactly the same effect upon ICE vehicles as EVs, since aerodynamics for both face the exact same laws of physics.

Gas vehicles also waste fuel running the AC compressor, just like the EV. That's why we used to have those articles telling us whether it was more efficient to run the AC or crack the window.

Really, the only big difference is cold temps. While cold affects an ICE vehicle's efficiency, it isn't nearly as much as an EV, due to the battery chemistry. With an ICE, because there are so many fluids involved, you had to warm up gently, which wastes fuel. I remember my dad running the car for 15mins before he'd drive away in the cold morning, after unplugging the engine block heater.

Then, my dad would also add dry gas fuel treatment to reduce the risk of condensation in the fuel tank from causing issues, or he'd stop at the gas station more often, to keep a full tank of fuel to prevent condensation.

Then, he'd have to check his antifreeze rating of the engine coolant, to make sure it was protecting his engine, and flush it every couple years.

Then there were the engine belts he'd check and replace since when they got really cold, they were more likely to break. On trips, he'd carry a spare belt, just in case we broke down, and the shop we stopped at didn't have the correct replacement size.

I don't have to do any of those things my dad used to do for his ICE, when Winter comes. Of course, I have to learn new things to do to prepare to drive an EV in Winter.

I remember as a kid, when roadtripping in an ICE was more complicated than today, because gas stations were not open 24/7 on the interstate. Even today, you'd look at those signs telling you where the next rest stop was, with fuel and food, and you'd try to figure out if you could make it to the next stop, or had to stop now, to refuel. Is it really all that different in an EV? And, even with lots of 24/7 places, I still find if I have to exit the highway, independent gas stations that are closed at night.

If anything, the future with EV chargers everywhere there are gas stations today, should definitely be better, since EV chargers don't require the station be "open" in the same way that a gas station needs to be "open" with at least one person there.

Certainly, Superchargers aren't ubiquitous like gas stations, but with the advent of in-built GPS, it's only a minor hardship to plan station to station. Roadtripping in an ICE was pretty much rest stop to rest stop or bathroom to bathroom or coffeeshop to coffeeshop. Is there that big a difference other than nomenclature? You still have to stop every 100 to 150 miles? Why do I care if it's at a supercharger with a coffeeshop and toilet or not?

Driving an EV means learning new habits and forgetting old ICE habits, like looking at the prices while passing a gas station, and doing all those things like my dad did, plugging in the engine block heater, adding dry gas, checking the coolant and bringing a spare belt, etc. I don't miss it.