Tam
Well-Known Member
It does make sense for short-term owners....short term (3-4 years)?...
By the way, you are not the only one. Tesloop (when it was in business prior to the pandemic) did that too.
You can install our site as a web app on your iOS device by utilizing the Add to Home Screen feature in Safari. Please see this thread for more details on this.
Note: This feature may not be available in some browsers.
It does make sense for short-term owners....short term (3-4 years)?...
Your post pretty well describes the approach I took with my electric motorcycle, especially the running it down to zero bit. And for me this was again in violation of sound advice I was getting off Internet forums about lithium batteries. I actually wrecked the motorcycle after about 3 years, and at the point I wrecked it there was definitely some degradation of the batteries. The motorcycle started out with about 60 miles of range, which I proved a couple of times (One time I had to sit with it plugged in at a gas station for an hour or so until it had enough juice to get me home.). I’d guess the range by the time I wrecked it was around 50-55.Really how much truth is there to this battery charging nonsense? Don't charge to 100%, dont drain below a certain percent.
What do you think is going to happen to my batteries? Really, anyone have experience with this? I will share my side below, since I think a lot of people out there are scared to even try this for a week. I've done it for a year and driven A LOT.
I have had my Model 3 performance for about 1 year now. Its got 24k on the odometer. Obviously a daily driver.
My charging habits.
Charge to 100% every night (home charger)
Drive it down to whatever it takes to finish the day. Sometimes 10 miles left sometimes 20 miles left sometimes 80 miles left, then back home to the charge to 100% for the next day. Again, EVERY night at my house it plugs in and charges to 100%. I have the $500 tesla wall charger.
When I bought the car I needed those miles because of all my driving. I literally only bought the performance for the extra miles, I would have gladly taken the long range but the wait was too long.
I never realized the games Tesla wants us to play. Only charge to 80% and only run down to 40% or 20% or blah blah blah. If I knew that I would say the car is a bait and switch. So what did I decide to do? Just drive the car and use the car. Like a gas car I fill it up run it to E like a gas car, and like a gas car I've hit the E in my Tesla and driven to the "gas" station with nothing in the tank.
I've brought my tesla down to 0 miles 2 times since I owned it. THIS I avoid if I can because I cant just get some gas and drop it into the tank, I would have to find a plug and sit there for hours. Last time it happened was scary but let me offer up this info to the forum. At 0 MILES I could still drive 4 miles (3.5 at 60 mph on the freeway and .5 to the charger) Again. SCARY on the freeway at 0 miles
However it would be nice to know WHAT I could actually get at zero miles, on my gas cars at E I usually knew 5-10 miles was easy peasy.
Also you might ask. WHY? Why drive this way and not follow the rules by Tesla and some owners advice online....Why? Cause I dont have time to sit back and watch Netflix and chill at chargers around town 2 times a day. I would rather I charge at home. I would rather "destroy" the batteries then spend 20-30 min a day, almost every day, at a charger as to not dip below a certain percentage.
Also, I keep cars for 2-3 years. MAYBE 4. Is any of the above going to matter in the short term (3-4 years)? Will I have to replace the batteries? I dont know. I just dont. There is so much rhetoric and battery virtue signaling its hard to tell whats real. Hence this post.
What I CAN tell you is the car works the same as the day I bought it, charges the same, and same basic range since the day I bought it. So no noticeable battery issues from my habits....so far 1 year in and 24k.
Also, I keep cars for 2-3 years. MAYBE 4. Is any of the above going to matter in the short term (3-4 years)? Will I have to replace the batteries? I dont know. I just dont. There is so much rhetoric and battery virtue signaling its hard to tell whats real. Hence this post.
What I CAN tell you is the car works the same as the day I bought it, charges the same, and same basic range since the day I bought it. So no noticeable battery issues from my habits....so far 1 year in and 24k.
The scientific results that have been discussed here show that avoiding the low state of charge is not necessary or helpful for batteries and people who tell you to do that are wrong. So you are correct in not doing constant recharges to avoid low state of charge during your driving day.I would rather "destroy" the batteries then spend 20-30 min a day, almost every day, at a charger as to not dip below a certain percentage.
Just now with 0,15kW loadWe need to define how we measure the voltage or know that we use the same or different reference.
Theres only one solid defined voltage for a specific SOC, thats the OCV. With no load on the battery the voltage creeps up to the defined value after a period of rest.
Driving the car lowers the voltage depending on the power output. In Park after a drive the voltage is also lower due to the not yet recovered voltage and the load from the car in park.
At all loads the cell voltage bogs down and the bog varies with cell temp, load history etc.
View attachment 809736
This is a OVC voltage chart for a NCA cell (Panasonic 18650, I think).
Tesla on screen SOC is slightly lower than true SOC, due to the buffer below 0%.
I have a lot of screen dumps from SMT.
A couple of weeks since new:
3.82 average cell voltage when the car had been standing parked in the garage for about 5-6 hours, 54.72% SOC.
Not OVC, because the contactors close when unlocking the car.
After my regular 55% charges (thats about 57% true SOC) I can see the cell voltage 3.84v after the voltage drops from the charging session when using the log data of teslalogger.
More degradation than someone who only charges to 50% for daily use for sure. But...Really how much truth is there to this battery charging nonsense? Don't charge to 100%, dont drain below a certain percent.
What do you think is going to happen to my batteries?
It probably won't matter. If whoever buys it doesn't check for degradation, it might not even affect the resale value. If the car is owned by Tesla (you're leasing it), then it REALLY doesn't matter. The battery is a consumable component. Some people's charging habits are harder on the batteries than others, but I wouldn't consider your usage pattern to be "abuse", if you actually need all of that range.Also, I keep cars for 2-3 years. MAYBE 4. Is any of the above going to matter in the short term (3-4 years)?
Probably not.Will I have to replace the batteries?
The only thing I'd be worried about, assuming you're not planning on keeping the car beyond 2-3 years, is that if you are barely making it back with range in the low double digits, is that degradation will make it where you won't be able to even do all of the driving your currently do after 2-3 years. To reduce degradation, I'd (1) use the scheduled charging feature and set it to finish about an hour before you depart each day, so that the time spent at 100% is minimized, and (2) set the limit lower if there are any days of the week you won't be driving as many miles, so that it doesn't sit close to 100% for a good portion of those days.What I CAN tell you is the car works the same as the day I bought it, charges the same, and same basic range since the day I bought it. So no noticeable battery issues from my habits....so far 1 year in and 24k.
It's clear that if you need to charge every day to 100% and you run it down, you drive very significantly every day. Which means that the amount of time spent at 100% is probably low, as soon as it gets there you need to drive in a short time period and it goes back down. This is better for the battery than sitting at 100% for any significant length of time. Even still, if you lowered the max to 95% that would lower degradation. Or if you made sure that the 100% was achieved immediately before you travel using scheduled departure so the time at high SOC is minimized.
The battery will probably not be damaged in a major way--which I define as catastrophic failure. You will have more degradation than people who drive less and keep the battery max at a lower percent SOC at most of the time. It's unlikely to need full replacement because of major degradation.
( It's only maybe storage at 0% for a long time weeks/months which might hurt with self-discharge, but maybe not). As I've written above, avoiding holding at high state of charge times the time at that SOC is most important. If you can make it from 90% to 2% every day, then that's fine.
The reason I say "virtue signaling" is someone posted to the forum asking how far he can take it at 0 miles (I dont have it set to %) and I was interested in this too since I wondered how long I really had that day to get to a charger before it shut down on me in the middle of freeway traffic. So as I sat at the charger. Hands trembling since it was a close one! I got on these forums to find out...what range did I have at 0 milesIt isn't 'rhetoric' or 'virtue signaling', or emotion here. It's attempting to translate independently discovered scientific results into practical implications for people to use.
BTW, 24K miles in a year is significant but not using full range every day: 250 miles * 365 = 91k. So still the direction is to avoid charging to 100% and letting it sit there, as that will definitely enhance degradation vs alternatives, particularly if it is hot.
When people say they would never do that....it’s because they don’t want to stop in the middle of the freeway...not because they are telling you off.The reason I say "virtue signaling" is someone posted to the forum asking how far he can take it at 0 miles (I dont have it set to %) and I was interested in this too since I wondered how long I really had that day to get to a charger before it shut down on me in the middle of freeway traffic. So as I sat at the charger. Hands trembling since it was a close one! I got on these forums to find out...what range did I have at 0 miles
Some responses were helpful in trying to answer that question but most responses were " I would never do that" IE - How dare you?
As far as the milage I rechecked I have had it for 11 months and 3 of those months I had a loaner while tesla was getting me a replacement part. So really I have been driving this car for 8 months.
To clear up my home charging habits:
I get home later in the day. Plug it in and its scheduled to charge at night (to save $$$) and ready by 8am. I usually depart around then if not then by 9am. If I am departing at 6am I set it to 6am.
Thanks for making my pointWhen people say they would never do that....it’s because they don’t want to stop in the middle of the freeway...not because they are telling you off.
It’s your battery to do as you please...but as in everything in life there is best practice....by adhering to a few simple rules (which aren’t rules, they are voluntary) you can preserve your battery....just like a careful owner would treat his gas car well and his dog even better
Why don't you gather the data if no one else has it and share it with us? I had to do this with one of my cars (pure ICE model) because I couldn't find any info on this. So I carried a gas can around in the trunk and drove it for over 50 miles after the low fuel warning light came on.The reason I say "virtue signaling" is someone posted to the forum asking how far he can take it at 0 miles (I dont have it set to %) and I was interested in this too since I wondered how long I really had that day to get to a charger before it shut down on me in the middle of freeway traffic. So as I sat at the charger. Hands trembling since it was a close one! I got on these forums to find out...what range did I have at 0 miles
A new paper on modeling calendar aging of batteries:
settings Open AccessArticle Calendar Aging of Li-Ion Cells—Experimental Investigation and Empirical Correlation
Some of it is not surprising: the very strong negative influence of high temperatures, and the negative effect of higher state of charge.
The key result in the model in equations 4-8. The main interesting result is that the assumption of aging as a square root of time is not a preferred model, and that a better model is an exponential (important at early times) added to a linear degradation. That's equation 4.
That's somewhat bad news in that longer term the linear degradation is worse than a square root, but the linear part isn't discovered until the exponential has been made unimportant.
The slope of the linear effect (\gamma(SOC,T)), equation 8. has a dependence on SOC. Note the "exp()" terms on right hand side multiplying all coefficients in equations 5-8. Those are the temperature effects: high temperature makes everything worse for degradation.
The SOC effect on the exponential term is more complex than the linear term (5) vs (8). That's a cubic which in figure 5 results in two maximums. Note also the figures are at pretty high temperatures (40 degrees C is very warm for continuous battery temperature). It's faster to get degradation results at high temperatures because everything happens faster.
I am not getting anywhere near the mileage that the model 3 long range is supported to get.
Could I somehow have the incorrect battery.
Does anyone know how the difference in the dimensions of the model 3 vs model 3 long range?
Not that new, I've already refered to that before
First of all, they might have a small point with the formula for calendar aging.
Second, other tests of calendar aging show other data, and in many cases it follows the "square root of time" very good.
Third, the difference between their formula and our "square root of time" is not that big. For our amateur calculations I think the square root works very well.
( I did a backwards BMS calib. recently to try to set my BMS from full range to to reflect the actual battery capacity. I think it worked, and now I have about 79kWh capacity according to my BMS. That is very close to my "square root of time" calcs. Using my logged data of average SOC and average temp I should have around 2.6% calendar aging now. The cycles should have worn around1% by now. This should put my battery capacity at around 79.1kWh if I calculate from 82.1 as the new pack number(once did show 82.0 nominal). My BMS calib put it at 79.0, and also a 0% to 100% charge one week ago indicated both 79.0 nominal and also the difference in nominal remaning was spot on. (79kWh -3.5(buffer))
I do not think the above is a coincidence.
There is a tendency for reserachers to use very high ambient temperatures and then draw conclusions like "we accelerated the calendar aging so each week was like one moth(or year).
In reality very high temperature (specially together with high SOC) kills the batteries. This makes the usual square root of time formula look bad, but when we look at researchers that use reasonable temperature, they do not get that behavoiur. The same is valid for using too high C-rate for charge/discharge cycles.
If you look very closely at the graphs you see that the linear part in their graphs actually show that the test points actually do show a not linear line but the curved line that fit the square root quite good. Also, from my point of view they stopped the test very very early in the "linear part". Way to early to make their statement clear.
There is an older report out trying to find a better formula than "square root of time". If I find it, I'll post the link later.
Agh... with all your posts I will have to brush up my math(s) The publications do show I imagine the worst case scenarios for battery degradation but, as has been mentioned by @AAKEE, by skipping over testing at lower temperatures, so far we have few hard data about the best conditions for longevity in the 0-20°C range. Excepting that is the experience from drivers in, on average, cool or cold areas.great info. Of course 1-a*(exp(-t)-1) - b*t can be approximated at early time intervals by 1-c*sqrt(t) Or lots of functions.
You're right that in longer time intervals the physics and results aren't clear for calendar aging in the regime that we would care about, such as 20 degrees C for 10 years. Extrapolation isn't fully valid when all the basic mechanisms aren't fully understood.
What matters is if there is a clear physical principle underlying calendar aging which means that the long term degradation is less than linear or is it linear, and the answer will come from chemistry experiments not curve fitting. Panasonic might know but they aren't telling.
If you look very closely at the graphs you see that the linear part in their graphs actually show that the test points actually do show a not linear line but the curved line that fit the square root quite good. Also, from my point of view they stopped the test very very early in the "linear part". Way to early to make their statement clear.
Have I misunderstood or is it my math neuron needing a reboot? The degradation "curve" from my battery appears biphasic when plotting NFP. Is this normal physical-chemical process or might it be influenced by following a more rigorous low SoC storage (~35% average) and charge to use, from when I got SMT in January? Average monthly battery cell mid temperature17.5 to 26°C. Or is it just as likely to be something else? Just curious!What matters is if there is a clear physical principle underlying calendar aging which means that the long term degradation is less than linear or is it linear, and the answer will come from chemistry experiments not curve fitting. Panasonic might know but they aren't telling.
The BMS guess the capacity, and it is no better than the software values put into the computer. This should not be mixed with the real capacity loss and the real degradation.Have I misunderstood or is it my math neuron needing a reboot? The degradation "curve" from my battery appears biphasic when plotting NFP. Is this normal physical-chemical process or might it be influenced by following a more rigorous low SoC storage (~35% average) and charge to use, from when I got SMT in January? Average monthly battery cell mid temperature17.5 to 26°C. Or is it just as likely to be something else? Just curious!
Battery is an LG M48 NMC.
View attachment 810533
Have you left the car sleeping to invoke OCV when at 100%? Or you drove it directly to under 55%.( I did a backwards BMS calib. recently to try to set my BMS from full range to to reflect the actual battery capacity. I think it worked, and now I have about 79kWh capacity according to my BMS. That is very close to my "square root of time" calcs. Using my logged data of average SOC and average temp I should have around 2.6% calendar aging now. The cycles should have worn around1% by now. This should put my battery capacity at around 79.1kWh if I calculate from 82.1 as the new pack number(once did show 82.0 nominal). My BMS calib put it at 79.0, and also a 0% to 100% charge one week ago indicated both 79.0 nominal and also the difference in nominal remaning was spot on. (79kWh -3.5(buffer))
To compare, I did drive about 20,5 K mi the first year. No appearent loss of range during the first 12 months.I've done it for a year and driven A LOT.
I have had my Model 3 performance for about 1 year now. Its got 24k on the odometer. Obviously a daily driver.
I use the Tesla WC as well.My charging habits.
Charge to 100% every night (home charger)
Drive it down to whatever it takes to finish the day. Sometimes 10 miles left sometimes 20 miles left sometimes 80 miles left, then back home to the charge to 100% for the next day. Again, EVERY night at my house it plugs in and charges to 100%. I have the $500 tesla wall charger.