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How much degradation?

Discussion in 'Model S: Battery & Charging' started by randvegeta, Apr 7, 2018.

  1. randvegeta

    randvegeta Member

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    So I roughly worked out that I had about 50KWH of usable capacity on my 2014 S 60. And by that I mean, when the car reports 100% full all the way down to 0%, but not including the buffer. And I think it's pretty normal for people to be able to drive quite a few KM below the 0% mark. So the 50KWH was supposed to be the charge level you could actually see.

    As I understand, when new, the usable capacity was about 58KWH, suggesting that if I have 50KWH, that would mean I'm seeing a 14% degradation.

    Recently my range SEEMS to have been going down, and it got me quite concerned. Now I'm not sure if I'm actually losing range, or my battery is out of balance, or if maybe I'm just interpreting the numbers wrong.

    So yesterday, took a short trip and started off with 90% charge. Arrived at destination with about 41% remaining. According to the trip computer, I used about 23.5KWH of power. This suggests that my full charge is about 48KWH, not 50...

    I plug in, and let it charge back up to 90%. Charged at a slow rate of 2kw over night, and it hits 90% about 5 hours before it's time to head back home. I look at the computer and it says it's added 25KWH to the battery. Interesting...

    Drive back home and my state of charge went from 90% to 46% (used 44%) and my energy consumption was about 20KWH this time. This suggests that 100% is about 45KWH? Something like that?

    How can there be such a discrepancy in percentage consumed and power consumed? And if 25KWH is added to the batter to replenish the 23.5KWH that was consumed, where does that 1.5KWH go? It's a good 6% difference. is this just charging efficiency? In which case, does the Tesla count the total power coming into the car? Or does it count what get's stored into the battery?

    Is 45-50KWH indicative of bad degradation or is this fairly normal?

    My rated range is about 275km at 100%. I cannot realistically get it more than that. Best I've ever seen was 280km, but that was last summer. This seems rather low to me, but I'm wondering if this is actually kind of normal. For the Americans who don't understand metric, 275km = about 171 Miles. I normally charge to 90% where I get about 248KM (153 Miles).

    I've lost about 3 - 5KM (2-3miles) of rated range since buying the car in 2016. The weird thing is, the lost range all happened immediately after I got my car back from a Tesla approved body shop. The body shop had my car for over a month and when it came back, the rated range was lower. I have since run the battery down to near 0 and charged to 100% to try and balance it, but never got that range back. I also don't use superchargers (ever!). What could the some reason be for the loss in range after the body shop?

    Anyone know what level of degradation would qualify for Tesla warranty replacement?
     
  2. henderrj

    henderrj Member

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    My understanding is that degradation is not any cause for warranty repair. As long as the battery works the warranty says it's good. However, it does seem like you're losing an abnormally great amount of charge. I have an 85 and still get 258 to 260 when I do a hundred percent charge. 205 for a 90%. And I have a December 2014 build with over 90,000 on the odometer. These are, of course, Imperial measurements, miles. I'd certainly talk to the Tesla folks and have them look at your logs.
     
  3. animorph

    animorph Active Member

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    Search for other threads on this subject. There's a new one every month.

    My short answer is that the car does not report kWh's used with any accuracy. Presumably there are a few energy drains that are not included in those numbers. Check your rated miles. They are as accurate as you can find, though even they are a calculated estimate.

    Battery degradation is checked by how many rated miles you have at 100%, new versus now. 90% can be used if you never get to 100%.
     
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  4. Boatguy

    Boatguy Member

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    My 2016 MS has lost about 7% of rated range. My 90% range dropped from 264 to 247mi.
     
  5. randvegeta

    randvegeta Member

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    Well that's a little difficult to know for sure since I did not get the car new, so I do not know how many miles/KM was available when it was NEW.

    Looking online, looks like about 208 miles for 100% and 187 for 90%.

    Mine is getting roughly 171 miles for 100% and 153 miles at 90% (I'm converting from KM as my car is set in KM/H).

    That suggests I've lost about 17-18% (or of 37miles) my capacity, which on an S 60 actually means a lot!

    When I first got the car, my range was slightly higher, at around 174 miles at 100%, so I've lost 3 miles in the last 18 months (all of which were realized between August and October of 2017). 3 miles = 1.5% of original range, or 1.75% of existing range.

    Does that seem a bit excessive for an S 60?
     
  6. Peter Lucas

    Peter Lucas Member

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    Several things. First, the cars display of range could be total fiction. For two reasons: One, it may assume a wh/mile consumption rate that is very difficult, or impossible, to achieve with any sort of ordinary driving. And second, the calculation of range may not even take battery degradation into account. I have both of these problems with my 2016 Model S 90D. Second, on my tests I found the cars display of % charge (SOC) to be very close to linear with respect to kwh used and miles driven. Using khw used and change of SOC, you have found your useable battery capacity to be 48 kwh and 45 kwh. These calculations will be better if you use a larger portion of a full charge. 45-48 kwh from a "60" kwh battery does seem low. I do not know how much degradation gets you a new battery. (My "90" kwh battery has 72-75 useable kwh. And the max charge range displays about 275 miles, when only about 200-220 miles is achievable)
    Charging efficiency. From this discussion ...
    Charging efficiency | Tesla
    ... you can see that charging efficiency varies between about 80% and 95%. Knowing that efficiency number for your car will help you know how much electricity you need to buy to keep your car going. But it will not be helpful for anything related to the performance of your car or battery.
     
  7. randvegeta

    randvegeta Member

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    I guess I will have to do some longer trips to get more accurate readings. Going from 90% - 40% and then back to 90% and back to 50% I suspect leaves a wide margin for error.

    Last summer I used to do these drives of about 220KM. I would typically charge to 90% (about 250KM rated range) and I would use just over 40KWH and arrive at my destination with around 20km of rated range left. Assuming the rated range is calculated at 180wh/km, that 20km remaining range works out to be about 3.6KWH. So with an estimated 40KWH used, and 3.6KWH remaining in the batter, it looks like about 43.6kwh (let's call it 44kwh) = 90% SOC. That translates to about 48-49KWH total rated capacity (excluding the buffer).

    As far as I know, the USABLE capacity of the original 60KWH (which was really 61KWH) battery was actually 58KWH, suggesting a loss of 10KWH, or 17-18%.

    Actually I find being able to achieve the estimated rated range to be not so difficult. Driving at 80-100km/h (50-60mph) on mostly flat roads will pretty much get you rated range. Driving slower means achieving better than rated range. In fact, I could pretty much hit rated range with an average speed of 110km/h (about 70mph) during the summer.

    I suppose I'll have to do a few full charges/discharges to get an accurate reading. I'll be happy if my battery basically just stays the same. Hopefully one day, Tesla will allow me to just buy a new and high capacity battery. Or maybe just get a salvage Tesla with a big battery and moving it to my S 60. I don't care about the badge or performance so much. I just want the range!
     
  8. WarpedOne

    WarpedOne Supreme Premier

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    I am missing a statment similar to "I charged it to 100% and then driven it down to single digit percentage in a normal 'nonsporty-nonhilly-nonchilly' way".

    SOC estimator looses its grip on battery capacity reality when only doing partial cycles.
    It tries to err on the safe side - i.e. not promising the range that might not be there.
    One can help it by revisiting 100% and 0% soc.
    Without trying this out all talk about observed degradation is moot.
     
  9. animorph

    animorph Active Member

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    17%-18% is the worst I've heard of. I agree, 208 EPA rated miles for an new (old version) S60, so I think your degradation is unusual. It could have a bad module in the battery. Or it might be that the previous owner abused the battery. You have apparently charged to 100%, so hopefully it has tried to rebalance itself.
     
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  10. randvegeta

    randvegeta Member

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    I've read that the 2014 S 60 is apparently the worst when it comes to degradation.

    I suppose it's possible the previous owner could have charged it to 100% excessively. But as far as I know, Supercharging is not even included in my car. By the time I got my car, it was a little over 2 years old and had done around 30K Miles. He never reset the Trip meter, so it's been counting the average consumption over the last 4 years now. I'm not a heavy footed driver, and I actually enjoy hypermileing (sometimes) and the previous owner had a lower average wh/km than I do! (Though my wife also drives the car and she uses at least 25% more energy than I do when I drive..)

    I'm hoping that my battery isn't actually getting worse, and that I just need to do a few charge/discharge cycles from 0 - 100%, and I'll get back to where it was last summer. We shall see.
     
  11. TexasEV

    TexasEV Well-Known Member

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    Don’t know what you read, but I had the same car (actually 2013 S 60, but it’s the same as 2014) and when I just sold it after almost 5 years my 100% charge was 199 miles. That was after charging the battery to 90% every night, and frequent charging to 100% for road trips. I probably supercharged 70-80 times. I think that degradation is normal, nothing excessive about it.
     
  12. Rocky_H

    Rocky_H Active Member

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    Where did you ever hear that from? I've never heard that. There is a pretty solid consensus that the first versions of the 90kWh battery were definitely the worst for that. The old versions of 85 and 60 (which you have) were really good.

    I'm going to agree with this bit. This seems to be the simple and real way to see if there is lost capacity. Trying to relate it to battery state of charge percentages isn't going to work, because it will still "say" 100% when it fills as far as it can fill, even if it has lost a fourth or a third or half of its energy capacity. But the "rated miles" or "typical kilometers" number is the car looking at the amount of energy it sees as usable and dividing by the efficiency rating constant to show a distance.

    So, getting to your 60 battery, yes, original rated total was 208 miles. The normal thing would be for something like 5-10 miles to seem to disappear from the full reading within about 6 months or so and then stay that way for the next few years. That's some combination of measurement inaccuracy at first and a little bit of degradation. So something like @TexasEV 's stats seem very normal--9 miles less in about 4 to 5 years. That full reading you have of 171 miles seems really low. When I've read about that happening a few times from the other forum, that is usually a whole module in the battery that has stopped working. A service center should be able to hook up to it and see that.
     
  13. sorka

    sorka Well-Known Member

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    Normal degradation, but anything exceeding 30% would require replacement in California, which you're not obviously. Does your country/state have any protections on the amount of degradation that is considered normal for EVs?

    Have you used a CANBUS scanner to look at the voltages of each string? If you have any strings that are completely out or have REALLY low voltage, that would not be normal degradation but an indicator of fused cells which is NOT degradation but failure.
     
  14. randvegeta

    randvegeta Member

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    Well today I had to make a little trip to my office about 100KM from my house, so I decided to do a range charge on the car.

    Set the charge to 100% and when it hit 100% it said it was still charging for a good hour or so. Switching to distance rather than charge, the rated range at 100% was 277KM. This is pretty much what I had when I first got the car, suggesting no degredation.

    Interestingly, I was able to drive it a full 5km before the range reduced to 276KM, and my consumption for those 5KM was about 1KWH (so it wasn't because I was going down hill or anything like that).

    I wanted to drive on the conservative side, so I wasn't hypermiling or anything, but I wasn't going particularly fast.

    I noted that by the time my SOC reached 81%, I had used 10KWH, suggesting 100% = 52.6KWH.

    I arrived at my destination with the following:
    - Total distance driven = 95.6KM
    - Total power consumed = 15.5kWh
    - Remaining Distance = 195km
    - Remaining Charge = 70%
    - (Extrapolated Full Capacity = 51.6kWh)

    Car was parked outside the office for a few hours, then made a few short drives around town running some errands.

    By the time it was time to head back home:
    - Total distance driven = 108.7KM
    - Total power consumed = 17.7kWh
    - Remaining Distance = 181km
    - Remaining Charge = 66%
    - (Extrapolated Full Capacity = 52kWh)

    On the way back home, I noted that when hitting the 50% mark, I had consumed 25.2kWh, suggesting 50.4kWh capacity.

    Finally arrived home with:
    - Total distance driven = 237.1KM
    - Total power consumed = 40.5kWh
    - Remaining Distance = 52km
    - Remaining Charge = 19%
    - (Extrapolated Full Capacity = 50kW)

    I would have liked to have driven around a little longer to get that battery down to 0% but it was getting too late.

    So it looks like my pack probably does have 50kWh of usable capacity and it has not really suffered any more degradation since buying it in 2016. My highest ever rated range was 280KM, and I suspect with a bit more balancing, I could probably get back those 3KM 'lost'. The fact I was able to drive 5KM before the counter dropped to 276 is probably a good indicator that it's actually there and the BMS just needs to be calibrated.

    I wonder, perhaps I should do this test again, getting to 0% and just keep driving until I get power limited, and see how many kWh has been pulled. Is there an additional buffer ABOVE the anti-bricking buffer? I've read that the S 60 has a 61kWh pack and about 58kWh is usable. So is this 3kWh the anti-bricking buffer, and there is a little extra above this but below the 0%?

    Apparently the S 85 D can do about 22km after reach 0% SOC. Of we assume the S 60 has... 10km, that's still around 1.8kWh.

    So if I can get 50kWh from a 100-0% run, and then an extra 1.7kWH of 'driving buffer', and a further '3kWh' of anti-bricking buffer, would that mean I actually have 54.7kWh pack, and lost 6.3 of my 61kWh, suggesting a 10 - 11% degradation?

    Or should I just be going by the rated range calculation. Currently getting 277KM out of the original 335km, suggesting a degradation of 17-18%.
     
  15. animorph

    animorph Active Member

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    Calculating battery usable kWh will drive you crazy. I'm sure that explains what happened to many TMC members.

    Glad to hear you don't seem to have any additional degradation. If possible I would still take it to a Service Center to see if the original 17% degradation indicates a bad battery module. If not, maybe a CAN bus reader and app should be able to figure it out as well. I don't think that requires a rooted car.
     
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  16. Rocky_H

    Rocky_H Active Member

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    No, no, NO. Don't go believing or spreading this rumor! There used to be something like that a long long time ago, like back in 2013-2014 or so, but they modified the software to remove that below 0 buffer way back somewhere in one of the 4.x software versions. Zero means zero and don't ever count on there being anything below that. Sometimes people get lucky, but the cars will generally shut themselves down right around the 0 mark, plus or minus a few miles or km.
     
  17. ACA Man

    ACA Man Member

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    Mine is actually worse than that at 21%.

    Going through arbitration process as we speak.
     
  18. randvegeta

    randvegeta Member

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    Last year, I distinctly remember driving at least 5, and probably 10km below 0 as on the way to the charger. I didn't even notice a power restriction after hitting 0.

    My car is a 2014 model and it has a very old software version. For some reason, since leaving the US, the software hasn't updated at all so I'm like version 6 or something.

    As for the S 85 going 22km past 0, that was from a video I saw on youtube, not just something I read.



    It was published around the same time I bought my car, and my car was shipped from the US long before this video was released. So maybe mine still has a buffer?
     
  19. sorka

    sorka Well-Known Member

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    Just wait until it hits 30% and then CARB rules will kick in and they'll have to replace it.

    Do you have CANBUS screen shot of the voltages for each string in say TM-SPY?
     
  20. Rocky_H

    Rocky_H Active Member

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    Like I said, sometimes someone may get lucky. Do we need to give the link again to the thread where many people have had their cars shut down with some positive miles still showing on the display? That happens, so the point is to not continue to spread this rumor that this mythical reserve is there and can be counted on. It generally isn't.
     
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