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Need for Level 1 Charging?

But that was not the issue you were bringing up. You complained of the amount of energy changing very quickly when left to sit and settle. And that is exactly what it does when it is in that part of the line with the voltage change being very steep.

You are confusing the voltage with state of charge. The two are very different things which is why it is difficult to determine state of charge from the voltage. Instead they measure the current and integrate that to measure the amount of charge remaining in the battery. To get energy they factor in the voltage curve, but the details of the curve shape does not cause the effect you are describing. 5% is 5%.


Well, not really. As some people have pointed out, Tesla seems to have re-instituted the "below 0 buffer", where the car will usually have a bit left when the meter gets to displaying 0%.

By "wee bit" you mean nothing you can count on? Yes. There is no hard limit to the power you can extract from a battery until the current and voltage drop literally to zero. The cells would be destroyed by that so they pick a point where the damage is minimal as they do at the top end. So the "zero" point is soft and they can play games with it.


I just reread it, in context, and yes, it absolutely makes perfect sense. This is what you said:

When you are driving the car, it obviously can't be plugged in.

Ok, now you are being absurd.


Sitting in a parking lot, it will frequently not be plugged in.

That isn't the issue. The issue is what Tesla says to do which is to keep it plugged in any time it's not driven.

The cars can sit for several days at a time without being plugged in, and they do not suffer harm from that either. "at all times" is definitely an exaggeration and not really what Tesla recommends exactly.

See, that's wrong. If the temps are well below zero, the battery needs to be plugged in so it can heat itself. In "several days" it would be depleted and damaged. THAT is what this is about.


But I was explaining why Tesla would give a recommendation similar to that about keeping the car plugged in excessively more than it needs. And having to fight that wives' tale misinformation about remaining plugged in leading to overcharging and exploding is one of the reasons they needed to say that, which was not related to idle drain energy consumption. So you brought it up, and I explained multiple reasons of why they published that type of recommendation. That was just one of them.

Yes they do!

I've given you examples of how the information is inadequate. I'm not going to rehash word salad with you.


As much as is really needed. It's the simplest way to get the best balance of most benefit for the most amount of people for the most use cases.
However, they are selling a consumer product. If they were to give excessive detail with many pages of steps and charts of various conditions and how to do things several ways to be the most perfect, it would have two negative consequences:

They already give excessive detail. People are used to ICE vehicles where you just have to keep enough antifreeze in it to keep it from freezing and you might need a block heater for winter starting. That's pretty durn simple. Tesla battery care is much, much more complex with cautions about charging, discharging, too hot, too cold...


1. It would be problematic for some people's use cases, where they need to use their cars outside of what is the most "ideal" treatment of the battery. And then that would mount up to lots of calls and service visits with people trying to reconcile that contradiction between needing a car they can use but being concerned with violating these recommendations and conditions.
2. It would feed the FUD of the haters and the fears of those who just don't know but are scared and worried about new technology they don't understand that well. If it has complicated steps and conditions they have to remember, that will seem overwhelming and discourage them from considering buying an electric car. And they would continue spreading these negative rumors about how electric cars are too scary and complicated to use.

So for those reasons, Tesla doesn't want to go too over-the-top with making it complicated. They keep it pretty simple, with the 50% to 90% being OK for constant daily use, and above 90% being OK for occasional use. Simple. Don't worry people. If you park with a very low state of charge, it will display a simple message saying you should probably plug in. If you charge it up really full several times, it will also display a simple message saying it's not a good idea to do that a lot. Also simple.

They need to tell you specifics of how much damage charging to 90% does, charging to 95% and charging to 100%. My cell phone tells me that. Seems simple enough to me.


No. That is not required. If people never look any of that up or do that research, THEY WILL STILL BE FINE. It is not required to obsess like that.

Obsess??? The battery in my car is as much as many people's cars! Yeah, I want to optimize the wear on it since it is the most expensive and most subject to wear and isn't really warrantied. Yeah, I want to take care of it, but I need to use it too!


As I just mentioned above, people don't need to look this up or worry about it. The car will give a simple message guiding you.

It does??? What something generic that you shouldn't charge beyond 90% "too much"? I don't recall seeing that because if it does, I would pretty much dismiss that as containing virtually no information. How much is "too much"???


It's fine. And really, this kind of seems like you're not being serious here. Plenty of things in life are known to be bad to do excessively or constantly--eating junk food, excessive alcohol, smoking, revving your car to redline, speeding. People moderate things all the time in their lives without having to know an exact quantified number of what the impact will be of doing it too much. "This generally isn't good; I shouldn't do it all the time."

Ok, so how often is ok? 50% of the time? 20% of the time? 10%, 5%? I often read that supercharging damages the batteries yet there is NO mention of that in anything from Tesla that I've seen. Are people making that up? Or is Tesla just not warning us about it for their own reasons?

I think you are being rather disingenuous about this.


I am sorry that you have so much anxiety about this, and I am trying my best to let you know that you DON'T need to obsess and worry about this so much. They designed these with extremely detailed systems to prevent people from being able to accidentally destroy them. It's the public--they know what the public is like. I wouldn't recommend what you are suggesting, of parking the car in the cold with a very low state of charge and then leaving it that way for a week. It's not that it's going to destroy the main battery, but just because you will probably cause yourself a lot of inconvenience.

You characterize my concern as "anxiety" because you've never bothered to actually consider the issues and so don't know enough to know what to be concerned about and what is actually ok.

So what is a "very low state of charge"??? 10%, 20%, 40%??? I don't have information to know what will work and what won't.


If the car is really running low and can't get recharged, it will just keep the main pack disconnected, with a safety buffer of energy left in there (that you are never allowed to access) so that the battery will not be drained completely and harmed too much. The idle systems in the car will eventually drain the little 12V battery, so you will have to get service or a tow truck or something to deal with that hassle and maybe have to replace that 12V, but you can get it somewhere and get it charging, and it will be OK.

So you don't know any more about this than anyone else? Ok, thanks for the entertainment.
 

RTPEV

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See, that's wrong. If the temps are well below zero, the battery needs to be plugged in so it can heat itself. In "several days" it would be depleted and damaged. THAT is what this is about.
This, along with new EV owners that could "forget" to charge is the reason why Tesla makes a blanket recommendation to just leave it plugged in all the time. Is that the optimal strategy for battery longevity? No, but it's close enough, and allows for a very simple recommendation on Tesla's part without having to give a class on battery chemistry. I don't think it was ever made as a best practice, but rather a best simple practice. Those that have attained a modicum of knowledge on batteries can adjust their practice to a more reasonable strategy.

Of course this does cause undue worry on the part of people that take the advisement as "thou shalt plug in your vehicle whenever it is parked", and there is a possibility that proper precautions are not taken (such as leaving the car unplugged for very extended periods where maintenance and self discharge could in fact damage the batteries), but the owner's manual does cover that at least.
 
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Rocky_H

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Sophias_dad

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See, that's wrong. If the temps are well below zero, the battery needs to be plugged in so it can heat itself. In "several days" it would be depleted and damaged. THAT is what this is about.
Ok, we are not talking about Fairbanks or Helena here. Page 184 of the model X manual says you should expect up to 1% per day of idle loss, and even mentions the 'parking at airport' for 14 days having up to 14% losses. I don't know how it can be any more clear.

As far as charging to 100% being 'bad', here's an old(2019) reference to Musk himself saying its not a good idea. Elon Musk explains why you shouldn't charge your Tesla battery to 100%
 
This, along with new EV owners that could "forget" to charge is the reason why Tesla makes a blanket recommendation to just leave it plugged in all the time. Is that the optimal strategy for battery longevity?

How does plugging in the car impact battery longevity? If anything that's good for longevity. Leaving it plugged in does not mean it has to charge above any set value like most PCs and cell phones do.
 
Ok, we are not talking about Fairbanks or Helena here. Page 184 of the model X manual says you should expect up to 1% per day of idle loss, and even mentions the 'parking at airport' for 14 days having up to 14% losses. I don't know how it can be any more clear.

So the car will never use more than 1% (of something, what exactly is the 1% of?) no matter what the conditions are? That's not accurate.


As far as charging to 100% being 'bad', here's an old(2019) reference to Musk himself saying its not a good idea. Elon Musk explains why you shouldn't charge your Tesla battery to 100%

The great thing about Musk is you can find where he has said so many things. He is the one who said it's fine to charge to 100% sometimes. My point is there is no information about how much harm that does to the battery or how often "sometimes" is. Is it 10% of the time, 1%, 50%?
 

Sophias_dad

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So the car will never use more than 1% (of something, what exactly is the 1% of?) no matter what the conditions are? That's not accurate.
There intent is no doubt 1% of the 100% full charge of the vehicle. The reason they don't put more conditions on it is that a) its probably not precise, b) the details are not very significant, and c) they'd have people like you saying "Your complex formula doesn't match my idle losses exactly, I'll sue!"

Maybe this link will help more... Elon Musk explains why you shouldn't charge your Tesla battery to 100% , where a battery expert's "clearly shows that frequent charges to 100 percent are detrimental to the li-ion battery cells themselves" Sure, maybe you can't trust him so much because he's worked with tesla. But its really not to Tesla's advantage to say "Don't charge to 100% often" though, unless its them trying to avoid warranty-replacement of batteries or pissed off customers. Tell us what YOUR battery design credentials are and maybe I'll pay more attention to your opinion than that of the experts.

I don't care how you charge your car or how often you charge to 100%. Just please don't come back complaining about battery degradation. I'm starting to think you started this entire thread just to complain.
 
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There intent is no doubt 1% of the 100% full charge of the vehicle. The reason they don't put more conditions on it is that a) its probably not precise, b) the details are not very significant, and c) they'd have people like you saying "Your complex formula doesn't match my idle losses exactly, I'll sue!"

Ok, you can make up any silly rational you wish. So the drain is 1% of the battery per day no matter what size battery? So the vampire drain is proportional to the size of the battery and does not relate to the electronic that remain on?


Maybe this link will help more... Elon Musk explains why you shouldn't charge your Tesla battery to 100% , where a battery expert's "clearly shows that frequent charges to 100 percent are detrimental to the li-ion battery cells themselves" Sure, maybe you can't trust him so much because he's worked with tesla. But its really not to Tesla's advantage to say "Don't charge to 100% often" though, unless its them trying to avoid warranty-replacement of batteries or pissed off customers. Tell us what YOUR battery design credentials are and maybe I'll pay more attention to your opinion than that of the experts.

You don't understand anything I'm saying. I have explained very carefully the issue is the use of words like "frequent charges" where no one defines what "frequent" means.


I don't care how you charge your car or how often you charge to 100%. Just please don't come back complaining about battery degradation. I'm starting to think you started this entire thread just to complain.

Yes, of course you don't care. I get that. But you don't get to tell anyone here what to do. It is obvious you just like to argue without trying to understand what others say. Instead you resort to hyperbole or simply ignore the remarks you are replying to and respond with spurious arguments. I will try to ignore your posts in the future.
 
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RTPEV

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How does plugging in the car impact battery longevity? If anything that's good for longevity. Leaving it plugged in does not mean it has to charge above any set value like most PCs and cell phones do.

It's potentially detrimental (although not significantly so) if for example someone has their charge limit set to 90% (because they heard Elon Musk say that's okay) and then plug in every day, despite the fact that they only consume 5-10% of the battery capacity. This means the battery will spend its life at about 85% average SOC, which I would argue is worse than spending it's life at a more optimal 50% SOC. Of course if you set your charge limit to 55%, that would be achieve the optimal 50% average SOC too, but the "recommendation" that people hear, and what many people follow, is to charge to 90% each and every day.
 

RTPEV

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Ok, you can make up any silly rational you wish. So the drain is 1% of the battery per day no matter what size battery? So the vampire drain is proportional to the size of the battery and does not relate to the electronic that remain on?
You are talking about two different things. Vampire drain is the power that the car's electronics use (telematics, security system, thermal management, etc.) even when the car is not "on". Usually this will be pulled from the 12V battery, although ultimately the main battery will have to be used to recharge that (and could certainly explain an apparent sudden drop in the main battery's SOC). You are correct that this power draw may manifest itself as a different percentage drop for different sized batteries, but another consideration is that the car is smart enough to put many of these systems into a low power state (shut them off) as the main battery approaches a low SOC, so once the car gets into a "danger zone", this vampire drain will become less and less.

The other loss is from self-discharge of the battery. This in fact is a constant loss of energy that does in fact track with the size of the battery. The amount of energy lost will be more in larger batteries, but on a percentage basis, it's pretty constant across all battery sizes. Think of each cell having a certain amount of leakage (1%). It doesn't matter if you have 70 cells or 7000, you're still going to have a given percentage of leakage for a given amount of time. The larger battery will just leak more energy.
 
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It's potentially detrimental (although not significantly so) if for example someone has their charge limit set to 90% (because they heard Elon Musk say that's okay) and then plug in every day, despite the fact that they only consume 5-10% of the battery capacity. This means the battery will spend its life at about 85% average SOC, which I would argue is worse than spending it's life at a more optimal 50% SOC. Of course if you set your charge limit to 55%, that would be achieve the optimal 50% average SOC too, but the "recommendation" that people hear, and what many people follow, is to charge to 90% each and every day.

Wow! So the suggestion that it's ok to charge to 90% is bad and leaving it plugged every day is bad and of course the combination of the two is bad. So we need to not listen to Tesla about the care and feeding of our cars?

How about Tesla gives us useful info rather than sound bites? Tell us how much wear is caused each time we charge to 90% instead of 80%. Tell us exactly when it's important to charge and when it's not.

Someone posted that the actual point the battery heater comes on depends on many things and can be between -20 °F (-29 °C) and 20 °F (-7 °C). That's a very wide range and it seems it would be useful to know what sets that number. 20 °F is not unexpected around here during the winter nights. It is also not clear how much energy would be used in that event. If a 5 kW heater is turned on full, a 100 kWh battery would be at zero in 20 hours.
 
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RTPEV

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Wow! So the suggestion that it's ok to charge to 90% is bad and leaving it plugged every day is bad and of course the combination of the two is bad. So we need to not listen to Tesla about the care and feeding of our cars?
See there's an example of how you can take a mostly benign statement and turn it into hyperbole.

Nobody (except you) ever said it was BAD. What I said is that it's worse, and only to an insignificant extent.
 
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You are talking about two different things. Vampire drain is the power that the car's electronics use (telematics, security system, thermal management, etc.) even when the car is not "on". Usually this will be pulled from the 12V battery, although ultimately the main battery will have to be used to recharge that (and could certainly explain an apparent sudden drop in the main battery's SOC). You are correct that this power draw may manifest itself as a different percentage drop for different sized batteries, but another consideration is that the car is smart enough to put many of these systems into a low power state (shut them off) as the main battery approaches a low SOC, so once the car gets into a "danger zone", this vampire drain will become less and less.

The other loss is from self-discharge of the battery. This in fact is a constant loss of energy that does in fact track with the size of the battery. The amount of energy lost will be more in larger batteries, but on a percentage basis, it's pretty constant across all battery sizes. Think of each cell having a certain amount of leakage (1%). It doesn't matter if you have 70 cells or 7000, you're still going to have a given percentage of leakage for a given amount of time. The larger battery will just leak more energy.

I've never seen anyone distinguish between the two losses of battery charge. From what I know about lithium cells in general, there is very, very little loss of charge if nothing is connected to them. So there is at least one if not two orders of magnitude difference between what YOU call vampire drain and the battery self discharge. I think we can safely ignore the self discharge unless you are going to lump the impact of temperature changes in with that. Charge at 70°F and park, returning to a 20°F battery and there will be a difference. I don't know that would be measured properly by percentage though since the issue is the size of the battery itself has changed, not just the energy stored. A 100 kWh battery is no longer 100 kWh. It's better to talk about kWh although it's a hard habit to break, using % or miles instead of kWh.
 
See there's an example of how you can take a mostly benign statement and turn it into hyperbole.

Nobody (except you) ever said it was BAD. What I said is that it's worse, and only to an insignificant extent.

So you live in a world where "It's potentially detrimental" is different from bad? Do you live in Washington, DC? Where I live we consider "detrimental" to be bad.

Then you use "insignificant". In my world, if it's insignificant, it wouldn't even be discussed except to say, "pffft, it's insignificant". Yet Tesla discusses it, in fact warns us about it, no?

What dictionary are you using?
 

Big Earl

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Yes, I'm trying to make sure I CAN drive when I return from the tropics to a frozen metro area.

Yep. I explained what to do back in post #16. Park with >60% and you’ll be fine for a week in the tropics, even if our region has a cold snap while you’re gone.

 
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Rocky_H

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I can see that this thread is never going to get anywhere. You are demanding that people give you exact, precise numbers for your situation. People are giving you answers of what things are generally better or generally worse. And you are getting angry and accusing people of things because that's not what you want, because it's not exact numbers for your situation.

But people can't give you that, because it isn't there. There are way too many variables involved. Where you live, how much you drive, when you drive (those relate to temperature issues), how much time is spent at various states of charge, and even slight variations in the manufacturing of the cells in your particular battery, etc., etc., etc. These add up to way too much variation to give a precise answer. So better or worse is as precise as the information can get, and you can choose to accept it or not.
 
Yep. I explained what to do back in post #16. Park with >60% and you’ll be fine for a week in the tropics, even if our region has a cold snap while you’re gone.

Yes, well, people say lots of stuff. I'm looking for the information to support such a claim. I believe I saw someone post that the battery self heating comes on somewhere between -20F and 20F. 20F is pretty common around here. I have no reason to think the car can protect the battery by running self heating for a week without depleting the battery. Is there any info available about this?
 
I can see that this thread is never going to get anywhere. You are demanding that people give you exact, precise numbers for your situation. People are giving you answers of what things are generally better or generally worse. And you are getting angry and accusing people of things because that's not what you want, because it's not exact numbers for your situation.

I'm not "demanding" anything. I'm saying there is no point in talking about generalities since that won't help when my car is bricked. If you are unhappy with the conversation, please do not participate.


But people can't give you that, because it isn't there. There are way too many variables involved. Where you live, how much you drive, when you drive (those relate to temperature issues), how much time is spent at various states of charge, and even slight variations in the manufacturing of the cells in your particular battery, etc., etc., etc. These add up to way too much variation to give a precise answer. So better or worse is as precise as the information can get, and you can choose to accept it or not.

I think you are being a bit pedantic. I especially like that you cite manufacturing differences. Manufacturing is about tolerances. I'm not trying to thread a needle. I'm trying to make sure I the car is not depleted which is something that can be prevented if the tolerances are known. If you don't have anything useful to contribute, I suggest you at least stop posting complaints. It's not helping anyone.
 
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