Jeff N
Active Member
- Oct 31, 2011
- 2,271
- 2,902
Tesla says (page 5):
https://www.teslamotors.com/sites/d...n_US.pdf?_ga=1.22147387.1019433549.1401054274
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https://www.teslamotors.com/sites/d...n_US.pdf?_ga=1.22147387.1019433549.1401054274
Jeff N
Active Member
- Oct 31, 2011
- 2,271
- 2,902
Tesla says (pages 17-19):
https://www.teslamotors.com/sites/default/files/blog_attachments/ms_owners_guide.pdf
I'm not saying the OP shouldn't charge near or at 100% daily. In their specific situation it might be the best trade-off but it is not the ideal charging pattern. Statements that routine daily charging to 100% result in no additional battery degradation are in conflict with Tesla's advice which is consistent with battery research.
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I don't think that this statement is universally accepted by the "tesla community" there are many heated threads on this subject.
this is poor advice, charging to 100% is ok sometimes and is never ok to let the car sit at over 90% charge for an extended period of time. in other words if you are going to drive off part of the charge immediately after charging to 100% that's ok but to charge to 100% and then park the car is not the best plan for long term battery health.
A guy in my local area has one of the first cars out there, very low VIN (Even lower than mine). He has been trying to kill his pack for awhile now (So he can get it replaced under warranty before it expires)- he will take it and charge it to 100% and leave it there every day. So far, he's not had more than 5% degradation.
I was talking to the TSC about it and what constitutes a pack failure; if I recall it's anything over 7% or something like that, but I wasn't clear if that was 7% year-over-year or 7% total, which makes a huge difference, and I didn't get a straight answer to that question.
I imagine if you had a 7% degradation before your warranty was up (in total), they'd probably replace it if you bitched loudly enough. Just my guess though.
I was talking to the TSC about it and what constitutes a pack failure; if I recall it's anything over 7% or something like that, but I wasn't clear if that was 7% year-over-year or 7% total, which makes a huge difference, and I didn't get a straight answer to that question.
I imagine if you had a 7% degradation before your warranty was up (in total), they'd probably replace it if you bitched loudly enough. Just my guess though.
Not that I would have a way of knowing but I'd be pretty upset if while visiting a SpC during a trip the stations were full and some of the people were just trying to save a couple of bucks by not charging at home.
Here's what Tesla says:
"Superchargers are free connectors that charge Model S and Model X in minutes instead of hours. Stations are strategically placed to minimize stops during long distance travel and are conveniently located near restaurants, shopping centers, and WiFi hot spots. Each station contains multiple Superchargers to help you get back on the road quickly."
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While I agree with your sentiments there are many who do utilize the SpCs as their primary source of power, and nowhere does it state that this is a misuse of the SpCs
Thanks for clarifying, I just don't want to break any rules or degrade the battery sooner if I do charge majority of the time with SpC. I figure if there is a SpC near work, commute can get up to 3 hours with traffic, it would be nice to just fill up while working.
a charging spot is NOT a parking spot, please don't block the spot all day
Boatguy
Active Member
Given the other threads on vampire drain, and my own experience with vampire, "leaving the car at 100% for long periods" seems to be essentially impossible. With vampire loss at 1-2 kWh per / day, within a week you're back to 90% or less.
The main difference is how much the A/C and cooling pump run to keep the cells cool. None to very little with the 14-50, sometimes a great deal at an SC. So the SC uses more power to get the charge, and the cells get warmer. I don't believe anyone other than the Tesla engineers know exactly how much warmer they get.
However, it's always more convenient to charge at home overnight with the 14-50 than it is to use an SC and wait.
As a practical matter when living in a situation with limited access to charging at home for a few months between moving to a new house that does have home-charging, it is not likely to violate anyone by using a SC in order to operate your car on a daily basis.
If you want or need to wait the extra time at the SC to top up from 90 to 100% then so be it. But don't try to scare new owners about imaginary dangers of charging to full or overusing SC--that is just rude.
There is from another thread by david99 with a link to the survey data, Impressed how the battery holds up after 73k miles , in which he summarized the overall trend:
"There is a page sorting the data based on daily charge level and supercharger use. It seems to show that both Supercharger use and charging to 100% more often doesn't affect battery degradation much. At least the data doesn't show a trend."
Tesla Motors has taken all the hassle and worry about battery management off of the owners--and they put their money where their mouth is, by offering the best warranty of any EV. Don't Worry, Be Happy...
If you want or need to wait the extra time at the SC to top up from 90 to 100% then so be it. But don't try to scare new owners about imaginary dangers of charging to full or overusing SC--that is just rude.
There is from another thread by david99 with a link to the survey data, Impressed how the battery holds up after 73k miles , in which he summarized the overall trend:
"There is a page sorting the data based on daily charge level and supercharger use. It seems to show that both Supercharger use and charging to 100% more often doesn't affect battery degradation much. At least the data doesn't show a trend."
Tesla Motors has taken all the hassle and worry about battery management off of the owners--and they put their money where their mouth is, by offering the best warranty of any EV. Don't Worry, Be Happy...
At most the SC charges at 1.5 C and that's only for a short time. The information about high charge rate degradation (found on the internet) is based on 4 to10 C charging and a bare (not liquid cooled) battery. Superchargers don't come anywhere near that level.
It's leaving the charge at 100% for a long time that is potentially a problem.
FWIW, at 68K miles and three years, I'm down 3% to 4%. I'm not sure how well the balance is as I haven't been down to a low SOC (e.g. 20%) for a very long time.
What I've always read (and I've read several enthusiastic tomes about this topic) is charge what you need and leave it plugged in. If you only drive 30 or 40 miles in a day, charge to 50% of the battery and plug it in each time. When you need to drive more than that, increase the charge on your phone. The charging computer is very sophisticated and it will manage both the charge level and the battery care.
For a trip, what I do is set it to charge to 95% the night before and when I get up in the morning, I push to 100% while I'm getting ready to leave. By the time I'm ready to go (less than an hour), its at 100% and has aligned the batteries. For Day to day driving, I set to 50% or 70% depending on the day. I almost always (like 99% of the time) plug it in when its in my driveway.
If you're interested, there's many many many many posts on this topic in the teslaforums site.
David99
Active Member
Charging higher than 90% is fine as long as you need it. It's not like 90% is perfect and 100% is bad. The lower the charge level the better, but if you have limited charging, it's fine to go higher than 90% as long as you use it right after you charge it. Just don't let the car sit for a long time at high levels of charge. So if you charge to 100% and then drive it down to 10% over the next few days, you are fine. Overall your average charge level is lower than if you would charge it to 90% every day.
Truth is, noone here knows how much faster the Tesla battery ages when charged to 100% vs 90%. All scientific data about Lithium batteries shows that at higher charge levels the battery ages/degrades faster. How much worse it is, we don't know for sure. For example we don't know if the difference between charging to 100% vs 90% is the same as charging to 80% vs 90%, or only to 70% vs 80%. I believe the fact that the charge level slider goes all the way down to 50% tells us that it is better to only charge to 50% rather than 60%, but below 50% the difference is too small to matter. The fact that Tesla only shows a warner when we charge higher than 90% says something as well. It's also safe to assume that Tesla doesn't want to scare owners about battery life.
Truth is, noone here knows how much faster the Tesla battery ages when charged to 100% vs 90%. All scientific data about Lithium batteries shows that at higher charge levels the battery ages/degrades faster. How much worse it is, we don't know for sure. For example we don't know if the difference between charging to 100% vs 90% is the same as charging to 80% vs 90%, or only to 70% vs 80%. I believe the fact that the charge level slider goes all the way down to 50% tells us that it is better to only charge to 50% rather than 60%, but below 50% the difference is too small to matter. The fact that Tesla only shows a warner when we charge higher than 90% says something as well. It's also safe to assume that Tesla doesn't want to scare owners about battery life.
1. The amount of difference in overall battery life gets smaller as the number goes down to 50%. That is 100% to 90% is some amount (X) better. 90% to 80% is a lower amount (X/2 or some such), and so on. I don't believe anyone outside of Tesla knows what the actual number is.
2. Leaving it at a high state of charge is bad for the battery, no on really knows how much, but it's bad enough for Tesla to issue a warning on the screen if you regularly range charge.
3. Driving below 50% generates more heat for a given power output than driving at over 50%, so I'm not confident that charging to 50% and then driving is actually all that good for the battery. If you're away for some time, setting the slider to 50% is good for the battery.
4. Charging to a low SOC will affect the algorithm and make the battery appear to lose range because the cells go out of balance. The balance circuits start when the SOC reaches 93% and than continue to work regardless of SOC (it may take them some time to finish balancing). So if you charge to a lower SOC charge to over 93% whenever you're going to go for a longer drive so that it won't sit at that level but the balancing will start.
2. Leaving it at a high state of charge is bad for the battery, no on really knows how much, but it's bad enough for Tesla to issue a warning on the screen if you regularly range charge.
3. Driving below 50% generates more heat for a given power output than driving at over 50%, so I'm not confident that charging to 50% and then driving is actually all that good for the battery. If you're away for some time, setting the slider to 50% is good for the battery.
4. Charging to a low SOC will affect the algorithm and make the battery appear to lose range because the cells go out of balance. The balance circuits start when the SOC reaches 93% and than continue to work regardless of SOC (it may take them some time to finish balancing). So if you charge to a lower SOC charge to over 93% whenever you're going to go for a longer drive so that it won't sit at that level but the balancing will start.
WATTS-UP
Member
My battery lost 10% of charge capacity over two years. After mentioning it to the Service Center I magically got 26 miles back per charge on my next charge cycle. Did get an update the next day, I bet they changed the formula on how charge milage is calculated.
Boatguy
Active Member
Assuming those are real miles, the good news is that your actual battery capacity did not decline.
David99
Active Member
That's a minor factor. What happens is the voltage drops so the Ampere for the same power draw goes up. Electrical losses increase with Ampere so we are seeing slightly higher losses when the voltage drops. But that's not a big factor and mostly happens in the motor and inverter, only partly in the battery. The effect on the battery is minimal.
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