Range Loss Over Time, What Can Be Expected, Efficiency, How to Maintain Battery Health

[AAKEE]

Lol just out of curiosity, what does SOC mean?

Thanks for all the help to everyone!

SOC = state of charge, your charge level( % )

 

[gord99999]

Lol just out of curiosity, what does SOC mean?

Thanks for all the help to everyone!

Hi MD, SoC = State of Charge

 

[Dave EV]

I have data from two SuC sessions, both was at 38.0 C average cell temp just before connecting to the SuC. Both was done after long highway driving before reaching the SuC.
First was at 14C and second at 27C outside temp.

Cell temps hit about 54 average during SuC for me.

High 30C makes more sense than preheating all the way to 50C for Supercharging - perhaps I'm mixing up the heating target on the Model S/X when they preheat for maximum performance. 54C also makes sense - that's right under the active cooling threshold, so that's the point at which the car starts using the air conditioner to cool down the pack.

Also now that I have had time to think about this.. it seems too bad that you cannot enable an active cooling setup for the car, if you wanted to choose to use energy for this to preserve your battery (I would imagine the energy drain for this "maintenance" would not be desirable for some people so it'd be good to have a choice).

I use quite a bit of energy in this heat while my car is sitting in the parking lot at work .. it can be 10-15% over an 8 hour period. I was cool with that because I don't need the range during the week and would rather have the car taking car of the battery. But if it isn't actually doing that, seems like a lost opportunity.

Do you have cabin overheat protection on with AC? That's the only way I can think of losing 10-15% over an 8-hour period. Personally, I only use cabin overheat protection in fan-only mode. Still gets pretty darn hot inside on a 90F+ day with the car in the sun, though. I don't think it spends any of that energy cooling the battery - it all goes into the cabin.

It’s not clear to me that cycling the battery (using it) to keep the battery cool would be helpful. Because then you are putting cycles on the battery. And that also results in aging. It depends on how the temperature effect of aging, per hour, compares to the per hour effect of draining the battery to keep it cooler.

Yep - there is probably some threshold at which the car will turn on and try to cool the battery down - not sure what that is, though.

 

[miss demeanor]

I saw you have teslafi.
Look at Teslafi menu -> Charges -> Battery report. Theres your estimated range. You can see the average range for other teslas of the same model. If youre on the average line, your fine. If above its even better.

Lol it looks like I'm below the average

 

[AlanSubie4Life]

Lol it looks like I'm below the average

View attachment 709736

Close enough though. Yours is definitely a normal result - the average has to come from somewhere - some people do worse, others do better. All of them are normal results. The outliers are the ones where there might be concern. 2-3% off the mean is not an outlier in this case.

 

[ftmaybe]

It’s not clear to me that cycling the battery (using it) to keep the battery cool would be helpful. Because then you are putting cycles on the battery. And that also results in aging. It depends on how the temperature effect of aging, per hour, compares to the per hour effect of draining the battery to keep it cooler.

alright, how about a much smaller, expendable companion battery that runs to thermally preserve the bigger, more expensive battery?

 

[AAKEE]

Lol it looks like I'm below the average

View attachment 709736

Did you look at the graph? The BMS capacity estimate isnt a smooth line but more like a jagged one. 10 miles might be a temporary difference.

 

[AlanSubie4Life]

alright, how about a much smaller companion battery that runs to thermally preserve the bigger, more expensive battery?

Haha. You could plug into the wall, but as alluded to by @AAKEE, another factor to consider is the COST of all of this (in energy costs, heat death of the universe, etc.).

It’s simply not clear exactly how much need there really is for this - as @AAKEE mentions, the better strategy might be to simply leave the car at 50-60% SOC if the battery is going to roast.

Actively keeping it cooler? Not clear at all how much that would really impact things. And the costs could add up, even if it is being drawn directly from the wall (not to mention wear and tear on pumps, compressors, etc.). How much would they add up? In a hot environment, maybe 500kWh over a summer (just a wild guess based on 90 days of 10% usage)…so $50-$250 per year. Not clear that that is worth it for a couple % better capacity (not clear how much it would help).

Basically the trade offs are far from clear. I’m sure Tesla has thought about it though.

 

[miss demeanor]

Did you look at the graph? The BMS capacity estimate isnt a smooth line but more like a jagged one. 10 miles might be a temporary difference.

I haven't had the car long enough for the graph to show up I guess, it doesn't show anything, since I've only had the car for 4 days now.

 

[jjrandorin]

Is it normal for my High Range mileage to be 280 after 3 years and 24k miles on my M3 LR AWD?

Yes, its normal (and does not impact you in the slightest since by your own statement you drive 10 miles back and forth to work each day). Some people really enjoy obsessing over this stuff, even though it doesnt impact them materially in the slightest. Only you know if you are one who enjoys it.

I happen to be a firm believer that "most people" do NOT need something like teslafi, etc because it presents some data in such a way as if its authoritative, and it really isnt.... and it drives some people to dig down a rabbit hole they cant do anything at all about.

 

[miss demeanor]

Yes, its normal (and does not impact you in the slightest since by your own statement you drive 10 miles back and forth to work each day). Some people really enjoy obsessing over this stuff, even though it doesnt impact them materially in the slightest. Only you know if you are one who enjoys it.

I happen to be a firm believer that "most people" do NOT need something like teslafi, etc because it presents some data in such a way as if its authoritative, and it really isnt.... and it drives some people to dig down a rabbit hole they cant do anything at all about.

Thanks, that puts my mind at relative ease haha; you're absolutely right about going down the rabbit hole for a car I've had the pleasure of driving for 3 days before going bonkers!

 

[Candleflame]

I'm definitely on board with the strategy of charging to ~60% or so and keeping depth of discharge to a minimum. It's the right choice according to the evidence (if it works for the end user - it doesn't work for everyone due to particular (common) use cases).

But whether you "need to lose 10% over two years" - that is definitely the big question! I haven’t seen a ton of evidence that specific optimal treatment of the battery is strongly correlated to capacity loss for Tesla vehicles (even though it should be!), but sticking to proven best practices for Li-ion batteries can’t hurt, and probably does help in general. Certainly there are a couple examples here of people using the lower SOC and having good results. But overall trends? I have no idea. It seems like there are plenty of examples of people with ~70% SOC habits with low depth of discharge daily charging, which you’d think would be pretty healthy, who see ~10% capacity loss after a couple years. And others with similar habits who are doing noticeably better.

Time will tell for 2021 vehicles. Was interesting to see the TeslaFi fleet data for 2021 - but a very small sample size it sounds like? And possibly some TeslaFi users would be predisposed to higher capacity loss (might be one of the reasons they sign up, for example!).

Will see what the next year brings…



I agree they don't seem to be software locked.

I know that some LR vehicles exist which have very healthy packs...close to 82kWh (though I think I'm taking your word for this (which I believe) and you've only seen them in other forums - I don't remember a direct report here? - my memory is poor as discussed previously on this topic, haha).

However, whether MOST LR vehicles will go to those levels is (I think) subject to some debate. From the reports I've seen, we routinely see 79-80kWh values for these LRs, and seldom see higher values, even with various 60-70% charging strategies employed.

Now...it true that's probably not a software lock, if there is a difference. But just searching for an explanation of what (I think) seems to be a small discrepancy in NFP between LRs (on average) and Ps (on average). Does that difference truly exist? Not sure.

The most easy way if you like a relaxed carefree life is to just follow the simple rules Tesla set, and no more thinking.
(Stay below 90% unless on a trip, always charge when possible and charge asap if you arrive with less then 20%.

On the other hand, there is more than one research report showing that the highest calendar aging might be below 100%. At least two or three research reports I’ve seen shows this (worst calendar aging at about 80-90% SOC)and comparing that result with other research reports that doesnt really show this you can actually find signs of that in these as well.

So if one is interested there is a lot of possibilities to keep the degradation down.
It is not really possible that it is the coincidence that is the main driver in degradation. Even if it is a big difference in packs from the factory due to the manufacturing process(which I dont believe because other lithium cells I’ve used show very small differences in capacity) you still can take actions to minimize the degradation. If I bought a long range because I needed the range and got it from the store with a appeareblack of 4-5kWh, Id make sure I didnt loose another 5 kWh from using it in a way that cause more degradation than needed.
But of course the way of handling charging habits is a matter of choice everyone need to make by them self.

From research we know what cause degradation, which is more or less driven by the laws of nature. Tesla can only do a few things to keep the degradation down so these laws will affect NCA cells in the same way it do in research.

Unofficial advice from tesla is to not plug it in immediately when low soc. The damage is already done and plugging it in causes more heat so its better on a cooler pack. The warning is more so ppl dont run out of charge.

Does any of this make any meaningful difference to degradation? Probably not. When people here routinely sit on 10% degradation after 30k kms and others on 6% after 200k kms then its always just the luck of the draw and minimal damage mitigration...

 

[jjrandorin]

Unofficial advice from tesla is to not plug it in immediately when low soc. The damage is already done and plugging it in causes more heat so its better on a cooler pack. The warning is more so ppl dont run out of charge.

Does any of this make any meaningful difference to degradation? Probably not. When people here routinely sit on 10% degradation after 30k kms and others on 6% after 200k kms then its always just the luck of the draw and minimal damage mitigration...

On my model 3, I have hit the "battery lotto" in that I have pretty minimal degradation, after 27k miles, with no real babying at all. Conversely, for my tesla powerwalls, I am on the complete other side of the spectrum, as they have 22% degradation after 18 months or so. I am actually hoping those (powerwalls) continue to degrade so I can submit a warranty replacement for them.

I am a believer that a lot of this is "up to chance" as it were, related to an individual pack, within certain tolerances.

 

[ftmaybe]

Conversely, for my tesla powerwalls, I am on the complete other side of the spectrum, as they have 22% degradation after 18 months or so.

wow….. no es bueno

 

[AAKEE]

On my model 3, I have hit the "battery lotto" in that I have pretty minimal degradation, after 27k miles, with no real babying at all. Conversely, for my tesla powerwalls, I am on the complete other side of the spectrum, as they have 22% degradation after 18 months or so. I am actually hoping those (powerwalls) continue to degrade so I can submit a warranty replacement for them.

I am a believer that a lot of this is "up to chance" as it were, related to an individual pack, within certain tolerances.

How do your charging schedule look for the car? Daily to ? When do you charge/how long part of the time does the battery sit charged to xx %?
What ambient temps do you have?

I guess the powerwall is charged by solar power? I guess it sits for long time each day at 100%?
22% is possible/normal/expected If the powerwall sits at 100% for long part of the day…?

 

[jjrandorin]

How do your charging schedule look for the car? Daily to ? When do you charge/how long part of the time does the battery sit charged to xx %?
What ambient temps do you have?

I guess the powerwall is charged by solar power? I guess it sits for long time each day at 100%?
22% is possible/normal/expected If the powerwall sits at 100% for long part of the day…?

I have said this a number of different times, but I plug in my car and charge it to 90% every time it hits my garage. The only difference in the past year vs before that time, is when it hits 90% I then move the slider down some to 80% just so the car is not bouncing between the 87-90% range,. because i dont drive every day. No "running it down to charge it up" no trying to balance the BMS, nothing.

Its in an enclosed garage that goes from low 50s in the winter to upper 80s in the summer.

The powerwalls are in that same garage (inside) right next to the car, and have the same ambient temperature. No, they do not sit at 100% "for a long time" because they get cycled every day. They are charged from solar and hit 100% during the summer around noon to 1pm, and start discharging around 3pm to cover afternoon AC use (summertime).

During the winter they hit 100% much later (as there is less solar during the winter) maybe as late as 4pm, but the powerwalls are cycled every single day, they do not ever sit at 100% for more than a few hours at max (I dont use backup only mode).

There is no correlation and no, 22% is not "expected" its just "battery lotto" as I said, as there are plenty of people with powerwalls who use them exactly the same way I do (load shifting is the normal way to use them in California due to how our utility rate structure) and some have similar degradation and some have almost none with same usage patterns.

People think they can nail this down, and you simply cant /shrug.... you are welcome to keep trying though. Thats about as much into this discussion as I am going to get.

 

[ftmaybe]

An ICE powerwall wouldn’t degrade! And you could fill it up to 100% in five minutes with gas! /FUD

 

[RiazKhan]

My 2019 Tesla 3 LR Performance charging only to 283 at 100%. Must be 310. Tesla says this is common in all cars. Afraid it will be SR miles soon.

 

[miss demeanor]

Does having the official Tesla wall charger help reduce battery degradation or is that a myth?

 

[AlanSubie4Life]

Does having the official Tesla wall charger help reduce battery degradation or is that a myth?

Myth.