M3 Winter driving causing battery degradation?

[chevycc]

First of all, before that someone complains, reason to post in CA forum:
1. number in km, don't want to deal with math
2. more users driving in cold climate

With that out of the way, here it goes.
Car in question, LR RWD M3.
I usually set my charge limit to 80%. And I try to schedule the charge to finish right before I take off in the morning. I charge inside an insulated garage.

What I noticed recently is that the displayed battery range on my car with 80% charged is 385km. I think it is a few km less than normal. Be honest, I don't remember the exact number but I feel the number was like 392km last summer. I did a, in my opinion, wrong doing last saturday by taking a chance and not stop to charge before heading home. I got home with only 2km of range. Although, i think BMS shouldn't have allowed me to damage battery in this case. There should be more reserve in battery.

I did verify the exact state of charge using tesla API. So it is correct with 80% = 385km. I know this number is different than estimated battery range, which based on environment and your driving pattern, is usually lower.

With the extra cold temperature in GTA recently and my
Just curious if any of you guys notice this. Or maybe my mine was serving me right on telling me summer range battery range # is higher than this.

 

[bijan]

I usually charge to 90%. I track my charges on TeslaFi (I've charged to 90% 87 times so far).
Today and yesterday I got 444.98km, which is a little less than I usually get, but not much.
The highest I've ever gotten is 449.75km the second time I charged the car at the beginning of October.
The lowest I've ever gotten is 441.19km at the end of October. I think this was due to battery calibration issue, and it went back to normal later.
Typically I get 447km-448km.

I've charged to 80% 6 times, my values were between 394.72km and 398.02km.

Edit: Charged with car at -13C and -12C yesterday and today (according to TeslaFi).

 

[chevycc]

Even with 441, 441/90*80 = 392. That was what I remember "normal" is.
I haven't paid attention to this number until recently. I thought the missing km was used to warm battery after charge finished.

 

[bijan]

Even with 441, 441/90*80 = 392. That was what I remember "normal" is.
I haven't paid attention to this number until recently. I thought the missing km was used to warm battery after charge finished.

Wait are you checking the number right when it finishes? Or in the morning several hours later? Because it will be lower several hours later. Just normal vampire losses. Doesn't start charging once it's done unless battery drops below a certain level.

 

[5_+JqckQttqck]

Even with 441, 441/90*80 = 392. That was what I remember "normal" is.
I haven't paid attention to this number until recently. I thought the missing km was used to warm battery after charge finished.

Once a month or once every two months, charge to 95%+. It will help the computer recalibrate the battery. It's natural to lose some km as normal degradation over the first year. Model S data show an average lost of 6miles. So in a year or two, our M3 max charge should be ~485km at 100% while charging to 90% should yield 445-449 (never 450 on the dot as each cell has degraded a bit).

I've been going to 90% since the temperatures dropped (like my cabin nice and warm) and always start the day with 447-449. Summer months I go to 70% unless it's for a road trip.

 

[ZooSean]

In Winter, range display is useless, just switch to percentage and forget about it until the spring...

 

[chevycc]

Wait are you checking the number right when it finishes? Or in the morning several hours later? Because it will be lower several hours later. Just normal vampire losses. Doesn't start charging once it's done unless battery drops below a certain level.

Right when it finish for the last couple of days.
I also checked via tesla API to make sure it is indeed 80%. I didn't trust eye balling the green charge bar.

 

[Pescakl1]

Check youtuber LikeTesla, she explained few weeks ago that you need to change regularly you target percentage and to charge few times to 100% for the computer to recalibrate itself, otherwise, it will start to believe you have less battery that what you have.

It is not degradation, it is needs of recalibration.

 

[chevycc]

Check youtuber LikeTesla, she explained few weeks ago that you need to change regularly you target percentage and to charge few times to 100% for the computer to recalibrate itself, otherwise, it will start to believe you have less battery that what you have.

It is not degradation, it is needs of recalibration.

ok, watching Kim's video now....

 

[ben1628]

Mine is 421 km for 85%. That's 396 for 80%.

In reality, it doesn't matter. I use %. When it's as cold as today, I just multiple it by 2, in summer, multiple it by 5.

 

[ewoodrick]

Summary

• It seems as if 80% charging max isn't necessarily exactly 80%, the sliders don't seem to have the ability to do exact anymore.
• It's winter, it's cold, the numbers aren't going to be right, just live with it and wait until it warms up. Generally, take 2/3 of Summer readings and be happy with anything more.
• Constant charging to less than something around 90% may result in the batteries not equalizing well and some of the numbers being off. Just charge to 100% every few months
• Did you worry this much about the number of gallons in your ICE? You do realize that the gas tank collects water and reduces the total capacity, didn't you?

The most important part, STOP WORRYING ABOUT THE BATTERY!!! As I said, take 2/3 of the number shown and use that as your max distance. That's all you need to do.

Enjoy driving!

 

[chevycc]

Not really worried about the realistic range. We know it's gonna be way less in winter, especially when using heat. Like Ben1628 said. I usually just hope for half of stated range. New Energy app do a much better prediction on realistic range. I can say it's pretty accurate given I took the car down to 2km range.

I am worried about the amount of degradation in 6month if it's real. I'm hope it's just BMS calibration like what you guys are suggesting. Will do a 100% charge when I have a chance next time.

 

[ben1628]

I did read a story of how a user thought the battery was degraded. Tesla told her to charge to 100% from time to time, and the range was backed up to where it was.

Remember, you get 8 years or 192,000KM on your battery and drive unit. The warranty on the battery, I believe, is at least 70% by that time.

 

[1Step2NoGas]

I've taken to simply leaving the energy display up while driving (when I don't need the map). What I've learned is that there is a considerable battery price to pay for the comfort of instant heat and a toasty cabin (~600wh/km for the initial few kms). I've also learned that many short trips wreak havoc with expected range. I've adjusted my habits and expectations accordingly.

I usually charge to ~90% and regularly see dots on both sides (regen dots and power dots) when I get into the car.

 

[ALSETJC]

Yeah I don't even bother in Winter, my range has dropped to 50% based on range estimator. Charge and drive. We can discuss charge capacities again in March or April . This is also why you need the largest battery in Canada to handle the cold compared to power output since we can't use the power half of the year but we do use the range quite easily with the heat on.

 

[ben1628]

That’s what my kid told me. Get the longest range u can get your hands on.

Tesla is no longer selling RWD long range

 

[chevycc]

Guys, just to be clear, there are two range figures.

1. Battery Range – This is the number shown in main screen or charge screen if you have chosen to shown km. It's the rated range given by BMS (battery management system) using the current state of charge. It disregards your driving pattern and weather factors. It only cares about the condition of battery. Theoretically, it should always be 499km if you charge your battery to full, even in winter. How fast it goes down, in other words, how much the battery drains is another question. Correct me if my understanding is wrong.

2. Estimated Battery Range – This is the figure the car thinks you can drive given the condition of your last x number of km driven. So, this is the realistic range. You can find it in forecasted range in the Energy app. We all expect this number to be way less than 499km in winter, no questions asked.

When we actually do find battery degradation, hopeful not this year, I expect the first number to decrease. In other words, BMS realizes that you can no longer take in as many kwh as before and therefore reduce your Battery Range km accordingly.

I’m hoping what I’m seeing is just a BMS calibration issue like many of you are saying. I plan to do a 100% charge before head out this weekend and see if it makes a difference. I’ve never charge the car to 100% during its life so far.

Will report back my findings.

 

[bijan]

Guys, just to be clear, there are two range figures.

1. Battery Range – This is the number shown in main screen or charge screen if you have chosen to shown km. It's the rated range given by BMS (battery management system) using the current state of charge. It disregards your driving pattern and weather factors. It only cares about the condition of battery. Theoretically, it should always be 499km if you charge your battery to full, even in winter. How fast it goes down, in other words, how much the battery drains is another question. Correct me if my understanding is wrong.

The one thing is that in winter and especially with the snowflake icon this is not the full picture.

In usual temperatures rated km is percentage times fixed multiplier.

In winter there are two percentages that you can get from the web API. One is usable percentage and the other is actual percentage (not sure what the actual names are). Once you get the snowflake icon (and even sometimes before that) these two percentages diverge. That is you might have 85% battery charge but only 80% is usable due to the cold. The rated km will then be 80% times multiplier and roughly 400km, whereas it may have been 425km if the battery was warm. I don't know if you can see those two percentages in the car but you can get them from the API. TeslaFi always shows the capacity and not the lower usable percentage.

For example this morning I gained 7km of range and lost the snowflake from preheating without charging for about 20 minutes (while plugged in), that was simply from battery heating up and usable percentage increasing.

 

[chevycc]

That's a good point.
In API, I think it's Battery Level and Usable Battery Level.
In my case, when I take off from garage, I don't have snowflake icon.

Range wise, beside those 2 stated, there is also "Ideal Battery Range". It's exactly the same as "Battery Range" in my case.

 

[Kenypowa]

1% is roughly 5km rated range for LR RWD. To the computer, 79.5 or 80.4% are both 80%.

I wouldn't worry too much about it. I recently charged to 100% and it is 498km. Basically I may have 1km, or 0.2% battery degradation after 28000km. Pretty awesome imo.