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Model 3 Performance Battery Degradation One Month (Story)

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The numbers in the graph ARE the 100% numbers. My 100% range is down to 282 from 310. When I charge to 100% I get slightly LESS than the 90% extrapolation says.

So I get 282 some days, and 285 some other days. BIG difference from 308-310.
The numbers I see on the stats are the same numbers I see on the dashboard (rounded to the nearest mile)

Since there is a marked/significant difference in the numbers that indicates there is some problem. That may be a BMS calibration or real degradation issue, no way I can tell.

I noted in one of your messages that you often time charging to finish relatively shortly before leaving again. That might leave too little time for the battery to balance fully.
One frequent cause of range reduction is an unbalanced battery. In "Roadster-Days" the recommendation often given in such cases was to time "standard-charging" (approx to 80%) to finish well ahead of departure time - at least 2 hours and to do that as regularly as possible. Balancing would only start after charging had finished and proceeded relatively slowly. To rebalance with that method could take a couple of months, but is of course gentler on the battery than going to 100% and waiting for balancing to proceed from there.
 
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Did you see what he was quoting before though? He quoted the other post of a person talking about 5% after 5000 miles and 6 months. Not 18 months and who knows how many miles.
This is definetely not normal, if it is real battery degradation (which it probably isn't)
I saw the quote. When within 18 months the initial drop happens varies. 6 months not unusual. As @ecarfan stated, this is “discovered” over and over again by each generation of owner.

Also, Tesla has been tweaking the BMS since 2012. I remember a lot of post software update rated range variance from 2012 to 2015, at which time it seemed to stabilize for the S battery chemistry. The 3 is different, and I suspect some of this is the same tweaking. I wish they were more transparent, but they are not. So best course of action is to relax and be optimistic and patient if your rated range is down < 10%.

If more than that, you should track because you may have a special case. But I’d recommend staying away from repeated deep charge cycles to “calibrate” or repeated > 90% to “balance”. If you decide to do that anyway, I’d suggest you also grind up some chicken bones, make a paste, rub it on your left elbow, and jump up and down. I hear that helps.
 
I saw the quote. When within 18 months the initial drop happens varies. 6 months not unusual. As @ecarfan stated, this is “discovered” over and over again by each generation of owner.

Also, Tesla has been tweaking the BMS since 2012. I remember a lot of post software update rated range variance from 2012 to 2015, at which time it seemed to stabilize for the S battery chemistry. The 3 is different, and I suspect some of this is the same tweaking. I wish they were more transparent, but they are not. So best course of action is to relax and be optimistic and patient if your rated range is down < 10%.

If more than that, you should track because you may have a special case. But I’d recommend staying away from repeated deep charge cycles to “calibrate” or repeated > 90% to “balance”. If you decide to do that anyway, I’d suggest you also grind up some chicken bones, make a paste, rub it on your left elbow, and jump up and down. I hear that helps.

Ah! Ok I was doing the right elbow...wish I’d known sooner. Will try next, thanks!

on a more serious note, however, I tend to agree with you that this is a software issue. I just got 36.2.1, and I have my fingers crossed! Particularly since this update is supposed to involve efficiency and energy consumption.
 
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I guess my battery was getting out of balance. I'm currently charging to 100% for the first time in many months, and it hit 100% 30 minutes ago and is still pumping in 3kW of juice. The app continues to read "Charging 30 min remaining", which hasn't changed for the past 45 min. This is new behavior for my vehicle. Previously, charging would stop as soon as the app got to 100%.
 
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For those that only drive 40miles per day. If we don’t charge everyday to use more of the battery, prevent short charging, prevent bms miscalculation....could we be screwing ourselves in the end? Was reading Tesla warranty info and noticed this. “See your owner documentation for important information on how to maximize the life and capacity of the Battery, failure to follow these recommended battery maintenance and charging procedures shall void this Battery and Drive Unit Limited Warranty.” Since they recommend keeping it plugged in...will they deny warranties if you don’t plug in every night?
 
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For those that only drive 40miles per day. If we don’t charge everyday to use more of the battery, prevent short charging, prevent bms miscalculation....could we be screwing ourselves in the end? Was reading Tesla warranty info and noticed this. “See your owner documentation for important information on how to maximize the life and capacity of the Battery, failure to follow these recommended battery maintenance and charging procedures shall void this Battery and Drive Unit Limited Warranty.” Since they recommend keeping it plugged in...will they deny warranties if you don’t plug in every night?

since I can’t edit my post...this is pretty much the only part of the battery section in the manual that’s capitalized and bolded. “Model 3 has one of the most sophisticated battery systems in the world. The most important way to preserve the Battery is to LEAVE YOUR VEHICLE PLUGGED IN when you are not using it.“ So instead of worrying about bms miscalculation should we just plug in everyday? even if only drop a couple percent or risk Tesla screwing us for potential warranty replacements If we don’t?
 
since I can’t edit my post...this is pretty much the only part of the battery section in the manual that’s capitalized and bolded. “Model 3 has one of the most sophisticated battery systems in the world. The most important way to preserve the Battery is to LEAVE YOUR VEHICLE PLUGGED IN when you are not using it.“ So instead of worrying about bms miscalculation should we just plug in everyday? even if only drop a couple percent or risk Tesla screwing us for potential warranty replacements If we don’t?

Yes: LEAVE YOUR VEHICLE PLUGGED IN when you are not using it.
 
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I guess my battery was getting out of balance. I'm currently charging to 100% for the first time in many months, and it hit 100% 30 minutes ago and is still pumping in 3kW of juice. The app continues to read "Charging 30 min remaining", which hasn't changed for the past 45 min. This is new behavior for my vehicle. Previously, charging would stop as soon as the app got to 100%.

Well Tesla has recommended me to do 100% -> 15% cycles once a month to keep the BMS calibrated...
 
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And, why would you do that? Out of calibration just means rated range display slightly off. Doesn’t mean you have less range. So you are going to do unnatural acts and unnecessary 100% charges, which are known to have cumulative impact??
We actually had this a bunch of times... Out of calibration means less capacity available, which in turn means less range.

The typical range you see when charged is based on the capacity of the car. If the BMS thinks you have less capacity, the car will shutdown if the BMS thinks you have amount X capacity even if you in reality have an amount X+%.

Same happens if the car thinks you have X+%, but you actually have X and the car will shutdown at X-% shown on screen.

The BMS is the one telling the car how much "gas" you still have left.

But since most people never drive more than 200 miles at once they will never notice it.
 
And, why would you do that? Out of calibration just means rated range display slightly off. Doesn’t mean you have less range. So you are going to do unnatural acts and unnecessary 100% charges, which are known to have cumulative impact??

Unfortunately, it does mean you get less range. The car will shut down when you reach zero miles on the battery display--so a miscalibrated BMS unfortunately means actual loss of practical range.
 
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Unfortunately, it does mean you get less range. The car will shut down when you reach zero miles on the battery display--so a miscalibrated BMS unfortunately means actual loss of practical range.

Actually that isn't true, it doesn't shut off at 0. It shuts off when the voltage drops too low. That could be at 15%, 10%, 5%, 0%, or many miles after 0% depending on how off the calibration is.
 
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Actually that isn't true, it doesn't shut off at 0. It shuts off when the voltage drops too low. That could be at 15%, 10%, 5%, 0%, or many miles after 0% depending on how off the calibration is.

Technically, that may be true. However, you don't drive the car till you run out of gas/electric, and then try to recover the car, every time.

You drive the car no further, than the gauge tells you so that you can get to where you need to fill it up. (with a personal safety factor added). So, if the gauge tells you that you have a range of 200miles left, then you wouldn't try to drive the car 300 miles. (Well, normal, sane people dont!)

So the gauge DOES in effect limit the number of miles you can drive the car. Doesn't matter if you measure the distance in miles or % battery, same decision.

Now, if the gauge is broken, miss-reading, or is inconsistent, (or changing more than is expected) YMMV as to what you do.
 
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This is a BS discussion. The estimator gets more accurate as you near zero, because it measures voltage. even if it didn’t, It’s simple math. If it’s off 10% at 90%, that’s a lot of miles. 10% at 10 miles is 1 mile.

Do you know how close you have to get to zero rated miles before things start to get “corrected” in terms of the estimate of available energy? I haven’t seen any evidence of a “recovery” of hidden/underestimated energy (which would show up as a slight increase in the discharge “constant”), but only have gotten down to 15% SoC recently. Got to 6% or so at one point but that was when I had 309 rated miles.

I’m only down to 304 now, but it seems pretty consistent even with relatively deep cycling on a road trip (repeated 15% to 90-100% charges).

Just curious if we have data on a situation where the BMS actually underestimated the actual available energy above zero rated miles, and how that “looks.” Seems to me the only way to “prove” the estimate is good is to discharge to very near zero and see whether the discharge constant is still very close to 230Wh/mi (234???) for a battery with a steady state temperature.
 
This is a BS discussion. The estimator gets more accurate as you near zero, because it measures voltage. even if it didn’t, It’s simple math. If it’s off 10% at 90%, that’s a lot of miles. 10% at 10 miles is 1 mile.
Well, that is not perfect math, because if your BMS thinks you have 280 instead of 310 miles, the difference is not 1mipe, but 30 miles. And yes, by the time you are at 10%, even if driving at typical range consumption (straight line) you will still have driven only 250 so miles, not 309 miles.

There are people who have tested this and you can too if your BMS is uncalibrated.

BMS uncalibration is a real issue and is problematic if you try to take all of the range you can. I regularly drive pretty fast(120mph or 180-190kmh) and a miscalibrated BMS will mean I can only go about 80% less range(90%+ heat loss + buffer) before the next Supercharger stop, which at these speeds is about 130miles. To me that is a lot of difference, for a person driving 50 miles a day at 60mph it is not.

So you have to put it in context, but BMS uncalibration is not as trivial as you make it to be. And some people are even 15% off...
 
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