Still, 51k miles and you're at 193 rated, that's pretty good. That's what, maybe 7-8% decrease from new. I have just over 30k and my rated range was 196 the other day, the first time I've charged to 100% in maybe 5 months. If I can still get above 190 rated miles at 50k miles, I'll be pretty happy.
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Still, 51k miles and you're at 193 rated, that's pretty good. That's what, maybe 7-8% decrease from new. I have just over 30k and my rated range was 196 the other day, the first time I've charged to 100% in maybe 5 months. If I can still get above 190 rated miles at 50k miles, I'll be pretty happy.
glhs272
Unnamed plug faced villian
So about these pictures... If you read up thread a page or two, I have been comparing my rated range and kWh extracted from the pack between now and a year or so ago. I am doing this to try to get a feel for how much range degradation I am getting. I made this trip again with the intent of not focusing on the rated range number at 100% but what actual kWh I could get. My original trip from a year ago got 54kWh from the battery with a little bit remaining and extracted at 312wh/mi. I did my best to run the same route but because it's warmer now, I had to drive as fast as I could comfortable drive and still hit about 312wh/mi. In summary I was able to get 54.9kWh from the pack. Pretty good I think. Most I have ever gotten in one session. I have run my battery lower before, but not from a full charge where I could get a complete measure of pack capacity. BTW, my charging habits: charge to 90% every day, charge as often as possible. I go on a road trip every 1 to 3 months which usually requires 2 or 3 range charges.
Here are a couple more pics from this trip right towards the end. These data points are just to try to make it easier to compare this one with prior trips.
This one is where the car was at when I hit the 54.0kWh:
This pic is of when I started seeing the power limiting bars.
So how much range degradation? Well it appears not much. Maybe a few miles, I could get 209 to 211 when new.
One minor note: for the last few months a 90% charge usually gets about 183. After this last bit of range charging and run to depletion, my 90% yields a 184-187. So, even though I have been charging to 90% daily, there still may be a tiny bit of out of balance or out of calibration. Thus, I have seen a minor rated range improvement.
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FredTMC
Model S VIN #4925
I guess so.
I think the battery range is only as good as the weakest "string" in the pack
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Yeah... I'm okay with my battery life. That being said, it's strange to see owners with hardly any degradation.
glhs272
Unnamed plug faced villian
There are probably a few different factors effecting my car's battery life. However, one of the reasons I charge only to 90% is because of the "weakest string". My thinking is that I want to wear all of the cells as evenly as possible. If the battery is left to run long for periods out of balance because of charging to lower voltages, it may reduce range faster than the normal degradation due to the slightly higher voltage at 90%SOC. You will have one string of cells work harder than all the rest which will amplify its weakness. This may be BS, but plenty of folks are running this experiment by charging to less than 90% and we can compare. I will be happy to test the always charge to 90% because I need to anyway (60).
mknox
Well-Known Member
Still can't seem to get mine to "stop" charging when it reaches 100%. This was earlier today after about 2 hours at a Supercharger. In this case, 100% = 245 Rated miles.
Todd Burch
14-Year Member
mknox, don't you typically charge to 80% (or didn't you used to?) I think your pack is way out of balance. (I noticed that my first car started losing apparent range (manifested by lower 90% or max charges) because I was habitually charging to 80%. On my new car, I charge to 90% most of the time and haven't seen my miles drop off.
Have you charged to 100% and let it run to completion at home lately? Suggest you do this. You're still putting ~5kW into the car....so it's topping off your lower cells.
mknox
Well-Known Member
This was for two hours at a Supercharger. I've let it run for about 4 hours at work on an 80 amp J1772 station (I have dual chargers) with the same result of never stopping. I either run out of time and have to leave or, honestly, get a little freaked at it throwing that much current for so long into an apparently full battery.
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I did 70% to 30% most of last summer and lost about 25 Rated miles of range when I eventually did a full charge. After that, I started doing 90% regularly and got about 5 miles of range back.
May just bite the bullet and let it run all night at 100% and see what happens :scared:
Todd Burch
14-Year Member
Pick a cool night to do it, and it actually may not be all that bad...Let it sit at 100% for about 4 hours.
Very interesting read. Is there a guide for the best way to balance the Tesla pack?
I have a 1st gen Honda Insight right now, and bought a "grid charger" to balance the pack. It charges the cells at about 300ma (they are 8Ah cells), and once the voltage gets up to about 170v (or about 1.4v a cell), you let it run for a few hours, and it "catches up" the lower cells to balance them all.
Could charging the Tesla up to 80% SOC at a fast rate, and then specifically picking a very low amperage to charge it up to 100% help to balance the pack (maybe if done so a couple times in a row with almost full discharges in between)?
I have a 1st gen Honda Insight right now, and bought a "grid charger" to balance the pack. It charges the cells at about 300ma (they are 8Ah cells), and once the voltage gets up to about 170v (or about 1.4v a cell), you let it run for a few hours, and it "catches up" the lower cells to balance them all.
Could charging the Tesla up to 80% SOC at a fast rate, and then specifically picking a very low amperage to charge it up to 100% help to balance the pack (maybe if done so a couple times in a row with almost full discharges in between)?
Two hours past 100%? I'd definitely shoot an e-mail to Tesla (with the rough timestamp) to see if they can pull the logs to learn anything.
Balancing the Model S is all theory. There is no official info from Tesla about how it happens and when and there is no recommendation on what to do. It definitely happens inside the battery, there is proof for it, but again, Tesla has not made any official recommendations about it. All you read here is speculation.
One common misconception is that not charging to 100% would cause the battery go out of balance. That's not true. The differences in the cells during the manufacturing are responsible for it. Cells are simply not perfectly identical. No matter what you do, they will differ. It makes no difference if you charge half or 3/4 or full, the differences in the cells will always cause them to drift apart. Balancing takes care of it. When exactly it happens is speculation. Most Lithium chargers do it after the charging is complete, but it could technically be done at any state of charge.
One thing that makes the rated miles go down when not charging full cycles is that the capacity can't be measured perfectly accurate. The rated miles are based on the real battery data and a mathematical model. The closer the state of charge is to the extreme ends (empty or full), the more accurate the cell voltage tells you what exact state of charge is. The longer you only run partial cycles the less accurate the data from the battery and the more you have to rely on the calculations and thus the higher the probability the calculation is off. Doing a full cycle on the battery (going from one end to the other) sort of re-calibrates this calculation. Tesla actually explained that in an official email. So charging to 100% after a long period of time of only partially charging it will recalibrate the range prediction. I don't know why so many people insist on saying it's balancing when Tesla specifically said it's a calibration issue and at the same time never mentioned anything about balancing.
One way or another, it is perfectly fine to charge to 100% here and there. It's not going to kill your battery. Doing it every day and leaving the car sitting at 100% for a long time isn't good for the life of the battery.
BTW, your Honda Insight has a different cell type. Nickle based batteries like to be at 100% and balancing them is much easier. You can just carefully 'overcharge' the pack. The lower cells will catch up, while the cells that are full just convert the excess energy into heat without getting damaged. The same thing would be catastrophic for Lithium cells. It would be damaging and they would eventually catch on fire.
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Todd Burch
14-Year Member
I interpreted his comment as meaning two hours total at the supercharger...so probably an hour or so at or near 100%.
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This is true. My personal experience has been:
With my 2012 S85, I frequently charged to 70 or 80% max, and with this saw my max rated range drift downward. Granted, I still believe the overwhelming majority of this was not real battery degredation but either imbalance or algorithmic issues.
With my 2014 P85, I charge to 90% 5 days a week. Doing this, my 90% charge has remained at or above 236 miles for all of the 13,500 miles on the car--and I rarely Supercharge or charge to 100%. If I were to do that once or twice a month, I'm pretty sure it'd be higher.
Anecdotally, it seems to me that some level of balancing happens at 90%. Charging daily to 90% seems to prevent the downward drift in rated range, whereas charging to 80% means your rated range drifts downward. But again, only Tesla knows--and why they don't publically state how this behaves is puzzling to me--especially given that they've now essentially opened up all their patents.
I'd LOVE to hear JB discuss balancing sometime. It would probably put this entire thread to bed.
I think it has to do with marketing and how they sell the car. They have been very conservative on technical details on how to charge the battery and all that. I think they don't want to portrait the car as something that requires technical knowledge and technical details about how battery imbalance happens and needs to be dealt with and degradation would just put more attention on it. That's what makes people skeptical about EVs. They want to present it as a simple and easy to use technology. Charging and range are the two things where EVs are still falling short compared to ICE cars. It wouldn't be helpful to confuse owners with technical details about battery balancing. It would be one more worry in the back of their head. Car guys like us love all that technical info, but I think for a sales and marketing point of view they want to make it look simple and fool proof. Well that's my theory at least
Todd Burch
14-Year Member
I think it has to do with marketing and how they sell the car. They have been very conservative on technical details on how to charge the battery and all that. I think they don't want to portrait the car as something that requires technical knowledge and technical details about how battery imbalance happens and needs to be dealt with and degradation would just put more attention on it. That's what makes people skeptical about EVs. They want to present it as a simple and easy to use technology. Charging and range are the two things where EVs are still falling short compared to ICE cars. It wouldn't be helpful to confuse owners with technical details about battery balancing. It would be one more worry in the back of their head. Car guys like us love all that technical info, but I think for a sales and marketing point of view they want to make it look simple and fool proof. Well that's my theory at least
I agree that's probably why, but that doesn't mean I have to like it
.I agree that's probably why, but that doesn't mean I have to like it
I wonder if one of us could actually get through to a person in Tesla Engineering to learn what the actual best practices are.
Something like "hey I'm a giant battery nerd, could you please talk about how your packs actually best like to be charged/discharged?"
I've read all the "general" statements about SOC, charge/discharge levels, etc....but I'm sure there's more detail that someone at Tesla could reveal to the true electric car nerds.
Yeah I've read WAY too much information about my 144v pack in my Insight. I was under the assumption that the lithium cells in the MS could be balanced the same way (charging to 90% SOC and then dropping the input Amperage to 1A or something super low and leaving that overnight)...
Whitepapers are good for this kind of thing. You want to geek out, here you go. I don't think people are asking for something on the front page of the website.
mknox
Well-Known Member
Sorry, I was probably not clear. I arrived at the Supercharger with about 30% SOC on the battery and set the slider to 100%. It was plugged in for about 2 1/2 hours, but I didn't check it constantly throughout (was having lunch and walking through a few stores nearby). I have an A-pack and noted that it was charging at about 80 kW when I left the car. I figure it was sitting at 100% for at least an hour, but likely more.
glhs272
Unnamed plug faced villian
A true 100% charge on a supercharger from low ~20% SOC to complete supercharger cut-off usually takes about 2-2.5 hours for my 60. It goes to 80% quickly in about 35mins, it's the last 20% that takes an additional hour and a half.
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