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How I Recovered Half of my Battery's Lost Capacity

Discussion in 'Model 3: Battery & Charging' started by SomeJoe7777, Aug 27, 2020.

  1. AAKEE

    AAKEE Member

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    #461 AAKEE, Jan 18, 2021
    Last edited: Jan 18, 2021
    Which part doesnt make sense ?

    ”Average remaining” range on the Energy app(I use average 50km) use the last 50 kilometers average consumption to calculate the remaning range. Perhaps last 30 miles if using miles. It uses the same calculation method: Remaining kWh divided by the average consumtion(Wh/km or mile) for the last 50km. If used backwars and divided by the remaining percentage of the battery you will get close to the ”Nominal full pack” value. Of course, as the car hides the 4.5% buffer on the last 50% of the battery you should do this with more then 50% in the battery.

    Heres one of my tests, landed in Northern Finland with 51%, and the calculation gave me 80.47 kWh battery size. The SMT reported 80.60kWh as ”Nominal full pack” The nominal full was taken just before leaving home. Theres a 0.13kWh delta, but the batteri meter in the var only shows whole percent so it might be a delta of 0.5%.

    I have don this calculation about 5-7 times between 51 and 90% SOC and it has not differed more then 0.5kwh, except for the last time( delta= 0.7kwh or roughly 1% of battery size) as shown in the earlier post.

    I say this method can be used if you dont have the Scan my testa app + the odb add on and the odb2-bluetooth dongle.

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  2. AAKEE

    AAKEE Member

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    I’d say simple way is to do like this:

    Check the energy app for the Wh/km or Wh/mile and multiply it with the range, after that divide the charge state in percent/100.
    Answer comes up in Wh, so divide by 1000 to get kWh.

    In the case below, just moved the car on the garden and took these pictures:

    262*251/0.82 = 80198 or 80.2 kWh.
    The SMT value for nominal full pack is 80.5 kWh.

    This should be good enough for own range calcs. 80,5 - 3.5(buffer) is 77kwh usable.

    If I go from full charge to empty with for example 200wh/km I get 77/0.2 = 385km range.


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  3. Candleflame

    Candleflame Active Member

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    yeah the roadster also runs the coolant pumps above 90% SOC with target 25C whereas model s/x dont run the coolant pumps above 90%. Even when its like 40C outside.
     
  4. AAKEE

    AAKEE Member

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    The 4.4V thing is the safe limit for chatching fire etc I guess. Even 4.2v for some time isnt that good for the battery health.

    If I remember it right Tesla started of with full charge at 4.15v, to keep the batterys in shape. Dont remember if it was the Roadster or the early S ?
     
  5. Battpower

    Battpower Supporting Member

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    Not sure 4.4V is safe or even relates to Tesla's previous of current call chemistry. I have see it as a limit that some lithium batteries can tolerate under test conditions.
     
  6. Dolemite

    Dolemite is my name

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    This post reiterates what another poster on here summed up a while ago:

    What's good for battery health is not necessarily good for SoC readouts.

    I've been charging to ~60% daily for months now during COVID. My "maximum range" has been all over the place. Whatever.
     
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  7. Candleflame

    Candleflame Active Member

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    No sorry your post makes perfect sense, like i said. What doesnt make sense is that people keep saying that you cant calculate the energy in the pack without driving it down from 100% to 0% inc. ppl like bjorn nyland. But they are all wrong because the bms has never been off even in the practical tests.
     
  8. AAKEE

    AAKEE Member

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    Oki, agree !
     
  9. XLR82XS

    XLR82XS D M C

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    Word. :cool:
     
  10. conv90

    conv90 Member

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    I have a little trick to know better the SoC when you divide by SoC if you have not SMT.
    .
    Your calculation of : 262*251/0.82 = 80198 or 80.2 kWh.
    if you took the 82% from the main screen under the battery, it can be 82,49% or 81,51% and displayed 82% rounded.
    Put a destination somewhere (nearest is better) and switch to trip screen. You'll have a bettere figure of the percentage looking at the graph. you can estimate if 81,8% or 82,3%..when displayed is 82%
     
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  11. AAKEE

    AAKEE Member

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    (I have SMT but for reference for others...)

    Good tip. I will test that and also compare to SMT.

    "My" calculation is within about 0.5% if done at high state of charges which is about 0,4kWh (and within 1% at 50% SOC) so it doesnt deviate very much from the BMS value, specially as the BMS calculation seem to vary at lest as much as the 0.4kwh.
     
  12. Candleflame

    Candleflame Active Member

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    The car actually does charge to 0.x percentages but for some reason there is no way to display that even with teslafi. For some reason the smartcharge project (in some states of australia and the USA you can join and get an adapter for data collection) does though.

    When you charge to a % the car will usually charge to XX.7%. I.e. if you set the dial to 80% it will charge to 80.7% +-0.1%.
     
  13. jim0266

    jim0266 Member

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    I've been tracking my battery stats with ScanMyTesla on my LR RWD since 6,600 miles, when it first reported 77.6 kWh. Like you I've largely stayed between 70-30% SOC when using the car. My car rests between 40-50% SOC.

    What I've found interesting is, up until the last few months my cell imbalance at 50% SOC would be consistently at 4 mV. It's now consistently at 6 or 8 mV. While my nominal full pack reading bounced around a bit by one or two tenths of a percent, the last few months those swings are now much wider. I dropped a full kWH recently, now down to 75 kWH at 10,753 miles.

    I've net yet tried to balance my pack. I'm showing 321 miles of rated range. I may charge up to 60% for a week to see if the cell imbalance improves again back to 4 mV, more out of curiosity. I do see a difference between what's best long term for the battery health, versus charging strategies to get the BMS to better reflect the true capacity of the pack.

    FWIW, I've only been below 30% SOC into the high 20's a few times and I've charged to 90% around 3 times. I've yet to charge to 100%.


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  14. preisedj

    preisedj New Member

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    Great post. But I just can't wrap my head around this issue considering the amount of money I had to pay for the car. Why should the end user have to go through all these gyrations just to get recalibrated. This is a very poor design.
    In my case my Model 3 SR+ used to show 240, but after a year, it barely shows 205. Tesla service told me none of this but politely told me that as long as the capacity is not less that 70%, i.e. 168 miles, it is within specs for warranty purposes.
     
  15. Black306

    Black306 Member

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  16. Candleflame

    Candleflame Active Member

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    this is good advice for people who have a supercharger every 100km. But for people who need to travel 400km between chargers the rated range is highly relevant.
     
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  17. KenC

    KenC Active Member

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    I wouldn't stand there at high tide. Judging by the algae and seaweed clinging to those rocks and the puddles, that spot gets sea sprayed as the tide comes in, and is likely underwater at high tide. No peace, harmony and balance when you're treading water and getting dragged out to sea.
     
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  18. 52 16 57 39

    52 16 57 39 2020 MYP, hitched & 1” UPP springs

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    I have a few hours of reading to do. Thanks all for these battery nuggets.
     
  19. Twiglett

    Twiglett Single pedal driver

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    Your average "end user" isn't going to obsessing about battery capacity any more than they would about oil levels.
    The biggest problem here is that this car/mobile computer makes all sorts of crazy stats available for everyone to insist that their interpretation of battery health is correct, then get bent out shape that their car might be broken in some way.
    Even worse when someone throws words like "degraded" or "bricked" into the mix.
    Best thing to do - throw away the battery monitor apps, stop obsessing about it and enjoy driving.
     
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  20. GtiMart

    GtiMart Member

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    Adding to what Twiglett said, it's a difficult problem. The only real way to estimate battery capacity is a full charge and complete discharge on a special tool. The BMS does its best to indicate capacity with its readings. Itsynot a matter of Tesla being lazy :)
     
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