Best to charge to 60%?

[spokey]

Assuming the Recurrent | Used Electric Cars Aren't Measured in Miles reports are telling me what I think they are and are in fact accurate I've seen a steady rise in my battery vs others since dropping to 55-60 normally. I do still go up for non-local days like today I"m going out this am and then a bit of a drive to get to a train to the city so I bumped up to 80.

I also always charge late.

 

[MY-Y]

...
As lithium batteries in general (NCA, NMC, NCO LFP) behave quite similar its not really probable that a new Tesla panasonic NCA (like 2170L or so) suddenly behaves completely different.
...

I really appreciate your contributions to this topic. I have a 2020 MY with an NCA and 2022 M3 with an LFP. From my observations on this very small data set, the NCA and LFP are quite different. The BMS on my NCA reported ~10% degradation after 10 months, where the BMS on my LFP reports 2.2% degradation after 10 months. The NCA is charged daily to 80% and my LFP is charged daily to 90% and often to 100%.

I see the batteries aging very differently. I wish I could get an LFP in the MY.

 

[AAKEE]

I really appreciate your contributions to this topic. I have a 2020 MY with an NCA and 2022 M3 with an LFP. From my observations on this very small data set, the NCA and LFP are quite different. The BMS on my NCA reported ~10% degradation after 10 months, where the BMS on my LFP reports 2.2% degradation after 10 months. The NCA is charged daily to 80% and my LFP is charged daily to 90% and often to 100%.

I see the batteries aging very differently. I wish I could get an LFP in the MY.

MD, Maryland?
How warm is the climate?

We could estimate about 5-6% for the first year if you have a “normal” climate, from the usual NCA graphs. 10% for the first 10 months is quite much. Do you have data from the initial point or is 10% compared to the spec?
A BMS Off track situation seems possible.


There is a quite recent research report of 2170 (21700) MCA cells, where the researchers could not reveal the manufacturer of the battery cells. Weight etc was identical to Tesla-Panasonic 2170.
Its very possible that this is the Tesla cells.

Heres other graphs from Panasonic NCA’s (18650):

I guess we have the ”same” battery? Panasonic 2170L with 82.1kWh new capacity?

My car (M3P 2021) was built more or less exactly two year ago, 17th Nov, and I did get it the day before New Years Eve.
Soon teo years, 53 K km and still 78-78.3kWh Nominal full pack and 490-492km range(out of 507km new).
I live in a cold climate so it helps, but keeping the SOC low and charge late is the keys I think.
My calculation for calendar aging / average SOC and average cell temps follows the graphs very precise.

 

[MY-Y]

Yes, Maryland.

I have a June 2020 77.8 kWh battery on my MY. I'm not too concerned about degradation, but would love to see my NCA battery degrade as slow as my LFP. I don't have graphs for my LFP, but here is how my NCA looks. (I didn't bother paying for teslafi on my M3.)

 

[AAKEE]

Yes, Maryland.

I have a June 2020 77.8 kWh battery on my MY. I'm not too concerned about degradation, but would love to see my NCA battery degrade as slow as my LFP. I don't have graphs for my LFP, but here is how my NCA looks. (I didn't bother paying for teslafi on my M3.)
View attachment 874030

Its obvious that your MY’s degradation curve is not a degradation curve but a “What the BMS believes” curve.

Batteries do not regain capacity. The car do not increase the true range. Real degradation is not reversible so the real capacity will only go down.

Your MY probably was not 10% down after 10 months. As most people seem to charge to 70-90% I would guess your MY is about on track with the average. I guess Maryland is about average climate.
Teslas BMS seems quite sensitive to the charging SOC target. The cars displayed range seem to change with the selected SOC. Some SOC or habits cause the displayed range to drop and some cause them to rise.

As the displayed range is affected by things that has not affected the real battery capacity (yet) I would say that we should not take too big notice of sudden range drops. Your battery’s real capacity will look more like the average fleet line and not going up and down. If it will be above or below the average will for the most part depend on the SOC the car has over time (and also the cell temperature).

If you need 80% because of the daily drive, you need it but if 55% would do it, that would cut the future degradation in half.
Also, setting the charging to be done just before the drive would further reduce the degradation.

 

[2101Guy]

I am almost positive that I’ve seen YouTube video comparisons with the rdoing testing at various states of charges, and there was minimal, if any, acceleration decreases when the battery pack was even at 50% state of charge versus say 90% or more state of charge. I’ll try to find a video and post them here.

 

[2101Guy]

A 2/10 of a second difference between 90% state of charge and 40% state of charge.2/10 of a second difference between 90% state of charge and 40% state of charge..

In my opinion, 2/10 of a second is going to be imperceptible difference to probably 90% of people driving a car and almost meaningless in the street. (Understood that on a track and race conditions you want every possible bit of acceleration and power available to you)

I’m still looking for the video of the refreshed S where the difference I think is even less than 2/10 of one second.

 

[MY-Y]

I should have clarified "BMS reported capacity" rather then degradation. I made a thread about not worrying about what the BMS says a while back. Reducing degradation stress - a tale of three batteries.

I'm guessing that my habit of charging to 80% will leave me with ~80% capacity in 10 years. If I'm extra careful, I'll have ~85%. I figure I enjoy the car more with a daily 80% charge, so I'll just sacrifice the extra 16 miles loss by 2030. For my use case, the real consequence of that is, at worse, one extra supercharger stop once a year.

Setting the charge to be done right before leaving is definitely a good idea. I do that too.

 

[P3dStealth]

I frequently see this sentiment around here. It seems a lot of people feel they don’t need to concern themselves with battery health because it will be the next guy’s problem after they sell their vehicle. My prediction is that it will soon become common for used car buyers to request a battery health test before purchasing. In this case, frequently abusing your battery (charging to 100% more often than necessary, letting it go to 0%, etc) may impact resale value. The latest release 2022.36 includes a Battery Health Test and you can bet I would insist on seeing that report before buying used.

Bottom line… be kind to your battery.

I think you are right. I think this is the reason that test is in the service menu... Why? Because if you run the test it tells you the battery health percentage on the battery page and the only other updated info it gives you is how many days it's been since the test was last run. Obviously you would need to know how many days it's been since the test was run if you are not the person that ran it. It's likely to show potential buyers.

It is probably a smart thing to look for in the used market. I know people that only supercharge and have no care for battery health because they leased so they charged 100% often just to avoid going to the charger in NY.

Then you have the opposite. I charge to 50% at home at 32amps mostly unless anything more is needed. I go out of my way to take care of the car as much as possible.

 

[Daekwan]

Model 3 has been on the market for 5 years now.. Model Y for 3 years now. Surely there is some real worth of evidence with these specific vehicles to show if its a significant difference between charging to something like 50% daily and 90% daily. Tesla's guidance is 50-90% daily.. which means that's exactly what I'm doing as they are the ones who have to stand behind the 8yr/150K powertrain warranty. For those who plan on keeping their car "10 years or more".. or those who want to make the next buyer get the battery in their used Tesla as healthy as possible.. then by all means knock yourself out charging to 50% daily.

Personally, Im sticking to 90% daily as that is within the recommended daily charging range from Tesla. And I drive about 120 miles every weekday and would always prefer having a little extra wiggle room, then having to hunt down a charger. I've never treated a car any differently than what the manufacturer suggests and what is written in the owner's manual.. and Im don't plan to change that practice now that I've switched to an EV.

Home Charging - Frequently Asked Questions

Learn more about how to charge a Tesla at home, including home charger installation costs, equipment options and how long it takes to fully charge a Tesla battery.

www.tesla.com

 

[spokey]

Model 3 has been on the market for 5 years now.. Model Y for 3 years now. Surely there is some real worth of evidence with these specific vehicles to show if its a significant difference between charging to something like 50% daily and 90% daily. Tesla's guidance is 50-90% daily.. which means that's exactly what I'm doing as they are the ones who have to stand behind the 8yr/150K powertrain warranty. For those who plan on keeping their car "10 years or more".. or those who want to make the next buyer get the battery in their used Tesla as healthy as possible.. then by all means knock yourself out charging to 50% daily.

Personally, Im sticking to 90% daily as that is also what's in the recommended daily charging range from Tesla. I drive about 120 miles every weekday. I've never treated a car any differently than what the manufacturer suggests.

Home Charging - Frequently Asked Questions

Learn more about how to charge a Tesla at home, including home charger installation costs, equipment options and how long it takes to fully charge a Tesla battery.

www.tesla.com

Sometime back in the 70s I was in for service at the dealership (not my normal practice). I think it was the '78 Caprice. I asked the service what Chevy had done to so that they could change from a 3,000 mile oil change to (I think) 5,000. Better engine tolerances/spec etc. He said they didn't change anything but that after 12,000 miles it was my problem and not Chevy's and he personally still recommended 3,000. Maybe true. Maybe not. But the point is the same. As long as your battery lasts through the warranty Tesla is off the hook.

 

[Daekwan]

Sometime back in the 70s I was in for service at the dealership (not my normal practice). I think it was the '78 Caprice. I asked the service what Chevy had done to so that they could change from a 3,000 mile oil change to (I think) 5,000. Better engine tolerances/spec etc. He said they didn't change anything but that after 12,000 miles it was my problem and not Chevy's and he personally still recommended 3,000. Maybe true. Maybe not. But the point is the same. As long as your battery lasts through the warranty Tesla is off the hook.

There is zero chance I’ll keep this car more than 8 years.

 

[P3dStealth]

There is zero chance I’ll keep this car more than 8 years.

I don't think there is anything wrong with this. Most people won't. Nothing wrong with it.

Just think what is going to eventually happen is the industry is going to figure out how to grade the condition of these cars at trade in or sale differently. Mileage is no longer a great reading because cars have different battery capacity and different charging habits.

You could be buying a Ford lightning or Tesla Cybertruck that was used as a portable generator at construction sites for more cycles than it was driven miles for example. How would you know?

 

[spokey]

There is zero chance I’ll keep this car more than 8 years.

then that merely goes back to that earlier comment

I frequently see this sentiment around here. It seems a lot of people feel they don’t need to concern themselves with battery health because it will be the next guy’s problem after they sell their vehicle. My prediction is that it will soon become common for used car buyers to request a battery health test before purchasing. In this case, frequently abusing your battery (charging to 100% more often than necessary, letting it go to 0%, etc) may impact resale value. The latest release 2022.36 includes a Battery Health Test and you can bet I would insist on seeing that report before buying used.

Bottom line… be kind to your battery.

I'm not even sure I"ll live to see the end of the warranty but my take is a bit different.

1. If it is true that say 50% is better than 90% and you don't need the 90% then 50% wins because it has to be better for the environment due to at least longer life.
2. I've never heard anyone say 50% was worse (ignoring the potential power cost for the dragsters)
3. Given the above I see no reason to go to 90% unless my next day travel needs it. Why not stay at 50%. Seems to do no harm and might do some good.

So I charge at the lower rate (actually 55 in my case). But I was doing a cousin reunion in NY so I popped the limit up to 88 the night before and set my departure to early afternoon. It's back down toady.

 

[Daekwan]

I don't think there is anything wrong with this. Most people won't. Nothing wrong with it.

Just think what is going to eventually happen is the industry is going to figure out how to grade the condition of these cars at trade in or sale differently. Mileage is no longer a great reading because cars have different battery capacity and different charging habits.

You could be buying a Ford lightning or Tesla Cybertruck that was used as a portable generator at construction sites for more cycles than it was driven miles for example. How would you know?

That's a great point. And just another reason why I don't worry much about things beyond what the manufacturer has asked me to do. There will ALWAYS be the guy on some internet forum that tells you he changes his oil every 3,000 miles because that's the way he has always done it.. and the way his dad did before him. Even though his manual now clearly states every 7,500 or 10K. I don't live in the past or the future.. but I do live by the book. Technology and the way we used that technology, now changes so fast who even knows what information we will have available years from now. When you think about it, EVs have really started to just leap into regular customers' hands over the past couple of years. That includes the mighty Tesla. Tesla alone has sold more EVs in just the past two years.. then it has in its entire combined total history going back to 2008.

As for judging the TRUE health of the battery before purchasing a used EV. Im sure manufacturers, service/repair centers, dealers, and all of these 1st/3rd party tools we use to monitor our EVs will continually give us more insight into actual health, degradation, cycles, history, etc. For example, I've run TeslaFi/Teslamate from the first week of ownership, and Im sure many others have too. The amount of data we have collected in these vehicles is absolutely staggering. I can tell you stats about my vehicles I never imagined I would even know. And In 5 years we will have unlocked even more information about these vehicles simply because no other consumer vehicle has been tracked and monitored this closely.

Finally, as the consumer/end-user.. this vehicle is still nothing but an appliance to me. I bought it to accomplish a certain need & want over a specific amount of time and when I'm done with it.. just like every vehicle I've owned before it... Im moving on to something. It's the same reason why so many people lease new vehicles now.. instead of bothering with the buy/sell/trade process. I already knew when I purchased this car I was looking to use it for 3-5 years and move on to something else.

 

[P3dStealth]

then that merely goes back to that earlier comment



I'm not even sure I"ll live to see the end of the warranty but my take is a bit different.

1. If it is true that say 50% is better than 90% and you don't need the 90% then 50% wins because it has to be better for the environment due to at least longer life.
2. I've never heard anyone say 50% was worse (ignoring the potential power cost for the dragsters)
3. Given the above I see no reason to go to 90% unless my next day travel needs it. Why not stay at 50%. Seems to do no harm and might do some good.

So I charge at the lower rate (actually 55 in my case). But I was doing a cousin reunion in NY so I popped the limit up to 88 the night before and set my departure to early afternoon. It's back down toady.

Agreed, only reason I charge to 50% mostly is because I drive 24miles every day and charge in my garage every day. If I drive further obviously I charge more. I just don't typically have the need so I don't bother. I am not actually going out of my way to charge 50%. I would not tell anyone to do that.

 

[pepperoni]

I think you are right. I think this is the reason that test is in the service menu... Why? Because if you run the test it tells you the battery health percentage on the battery page and the only other updated info it gives you is how many days it's been since the test was last run. Obviously you would need to know how many days it's been since the test was run if you are not the person that ran it. It's likely to show potential buyers.

It is probably a smart thing to look for in the used market. I know people that only supercharge and have no care for battery health because they leased so they charged 100% often just to avoid going to the charger in NY.

Then you have the opposite. I charge to 50% at home at 32amps mostly unless anything more is needed. I go out of my way to take care of the car as much as possible.

Eventually, I would expect battery health to be more important than mileage for EV resale value.

 

[2101Guy]

then that merely goes back to that earlier comment



I'm not even sure I"ll live to see the end of the warranty but my take is a bit different.

1. If it is true that say 50% is better than 90% and you don't need the 90% then 50% wins because it has to be better for the environment due to at least longer life.
2. I've never heard anyone say 50% was worse (ignoring the potential power cost for the dragsters)
3. Given the above I see no reason to go to 90% unless my next day travel needs it. Why not stay at 50%. Seems to do no harm and might do some good.

So I charge at the lower rate (actually 55 in my case). But I was doing a cousin reunion in NY so I popped the limit up to 88 the night before and set my departure to early afternoon. It's back down toady.

also a (heaven forbid) crash at 50% that starts a battery pack fire is going to less intense than a fire burning at 90% charge

 

[jcanoe]

also a (heaven forbid) crash at 50% that starts a battery pack fire is going to less intense than a fire burning at 90% charge

How so? The flammable materials in current lithium batteries include an electrolyte (we don't yet have solid state batteries) and the lithium metal. The size and intensity of a battery fire would be determined by temperature, access to oxygen for combustion. The state of charge, as long as there was sufficient charge to cause a failed/shorted cell to overheat and start a chain reaction with neighboring cells would not matter.

 

[AAKEE]

How so? The flammable materials in current lithium batteries include an electrolyte (we don't yet have solid state batteries) and the lithium metal. The size and intensity of a battery fire would be determined by temperature, access to oxygen for combustion. The state of charge, as long as there was sufficient charge to cause a failed/shorted cell to overheat and start a chain reaction with neighboring cells would not matter.

Did you read any facts in that mather?


The lower the SOC the lower the risk of fire.
The higher the SOC, the more dangerous.

The results show that both the SOC and incident heat flux have significant impact on the combustion behavior of battery. The battery with high SOC presents a fierce combustion process and higher surface temperature than the others, especially when imposed with the high external heat flux.

As a result, the high SOC battery under the high incident heat flux has the highest risk of ignition.

The fire risk evaluated based on the assessment methods shows that the high SOC battery possesses the higher fire hazard than lower SOC battery. The increase in incident heat flux can also trigger the higher risk. The current observation coincides with the above combustion analysis of battery

https://www.researchgate.net/profil...ent-heat-fluxes.pdf?origin=publication_detail

This study investigates the effect of the SOC on self-heating ignition of open-circuit LIBs using oven experiments. We find that SOC has negligible influence on the preheating and self-heating stages of LIBs, but significantly affects the ignition behavior. When the SOC is larger than 30%, self-heating ignition happens, and only if the SOC is larger than 80%, flames could occur.

https://www.sciencedirect.com/science/article/pii/S1359431122005683?ref=cra_js_challenge&fr=RR-1