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less than 200 miles. . .

Discussion in 'Roadster' started by tonybelding, May 6, 2019.

  1. tonybelding

    tonybelding Active Member

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    I hit an unfortunate milestone yesterday. I gave my 2010 Roadster a full charge in range mode, and the final readout was 196 "ideal miles" of range.

    When I bought the car several years ago, I could charge it up past 220. Even last month when I took a day trip around Lake Travis, I charged it up to 205 miles. There's a certain amount of randomness in terms of charging conditions (temperature, charge rate, etc.) and the precise number it settles on. However, yesterday was the first time I ever gave it a maximum charge and came up short of 200. Bummer.

    This morning it charged in standard mode to 155.

    I'm doing okay with it for now. It does have me pondering my future plans, though.
     
  2. Marius

    Marius Member

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    You are lucky. Mine has a range charge of 140 miles maximum. Standard charge of 105 miles. CAC 100.
    No information yet on any delivery date for a new pack which I ordered more then 1 year ago.
    The only way I can get around is with the JdeMo charge unit.
     
    • Informative x 1
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  3. supersnoop

    supersnoop Tesla Roadster #334

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    Pull the logs and check the cac over time. Also, give it a full charge and drive it down to below 10% in one session (one key turn). Then charge it back up and see if the cac improves.

    With the weather in the Austin area lately, my cac has been dropping a bit, too. It tends to be cyclical; dropping as the summer approaches and recovering as it cools off in the fall.
     
  4. scottm

    scottm Version 9 software sufferer

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    Is that battery pack upgrade for legacy Roadsters still being offered?
     
  5. gregd

    gregd Active Member

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    It's listed as "out of stock". Fleeting rumor is that there may be something new coming this fall? Fingers crossed.

    I'm still at 138.8 CAC (214-ish Range mode, 163 standard) on the original battery, but intend to keep the car forever. Battery and PEM are my big worries in the long term.
     
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  6. hcsharp

    hcsharp Active Member

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    How many miles are on your Roadster?
    That's funny mine does the opposite. It's increasing this time of year as the weather warms up. It always drops a few miles in the fall as things cool off.
     
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  7. tonybelding

    tonybelding Active Member

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    It's 39,000 and change.
     
  8. Stewie26

    Stewie26 Supporting Member

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    My roadster, #466, has 39K on it also. Standard charge using the 120 volt yellow cord is 173 ideal range. Funny thing, when I charge with the 240 volt it drops to 170- 171 or so ideal range. That said, I have never used the extended range so I have no idea what it would measure at.
     
  9. smorgasbord

    smorgasbord Active Member

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    FWIW, VIN1298 just turned 8 years old. It has 51.3K miles, original battery CAC is 139.52, and Standard Charge at 120v (long story) is about 169 miles about an hour after charge is complete.
     
  10. bolosky

    bolosky Member

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    My 3.0 battery in range mode no longer makes it to 300.
     
    • Informative x 1
  11. smorgasbord

    smorgasbord Active Member

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    I've seen this "one key turn drive to very low SOC" a few times. What's the basis for this? Is this actually worth doing? In reading the 3.0 battery upgrade thread, it seems that low SOCs permanently hurt the battery capacity.

    As I posted above, my original battery is doing pretty well. I typically drive about 50 miles/day a few days a week - but almost never take long drives anymore, so I haven't done a range charge in ages and haven't driven to the yellow battery color range warning level in ages either.

    I have an opportunity for a long drive coming up in a few days, but as it's a round trip, there would be a key-off in there, unless I did something crazy like bring a second key to lock the car with it "running" in Park. While I'm temped to see just how good my battery is or isn't, I'm also thinking that I should probably just stick to normal charges/drives. Thoughts?
     
  12. hcsharp

    hcsharp Active Member

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    Executive summary: 1. The "one key turn" theory is an old wives tale. 2. The 3.0 battery is not hurt by a low SOC.

    tldr version:
    Your question "What's the basis for this?" will garner multiple answers. Perhaps my answer should be considered my opinion only. The story goes that a Tesla Roadster engineer told a service tech who told a customer who told more customers who informed more service techs who told more customers and eventually it just became a fact. My own personal anecdotal evidence suggests that the algorithm that calculates your range gets more data if you deplete the battery more and makes an adjustment. I've never seen any evidence that the depletion of the battery needs to happen in one key turn. I believe what's important is that the algorithm gets a larger and more updated data set, not whether it's in one key turn or not. This also explains why your CAC and total range usually change in steps that are associated with long trips.

    As for the notion that low SOCs permanently hurt capacity, it's true that multiple small discharges cause less damage than one large discharge, given the same overall kWh. Having said that, I don't believe you would experience any measurable capacity loss after one or two deep discharges, or even half a dozen, especially with the 3.0 battery. It's more of a daily charging habit over a sustained period of time that you would start to notice a difference. I think the reason people have come to believe deep discharges cause immediate capacity loss is because that's when your CAC gets new and more plentiful data and makes an adjustment. The capacity was already lost before you made the long trip.

    The 3.0 battery has a discharge curve that safely goes lower than the original cells. But that added capacity is not utilized because the Roadster charging system cannot start charging at the lowest voltage the 3.0 cells can safely get to. As a result there is a small amount of wasted capacity that we can never use from the 3.0 cells. It is partly for this reason that I don't believe a very low SOC causes any damage to the 3.0 cells. Once again I think the low-SOC-damage theory comes from the fact that your CAC is often adjusted more than after smaller discharges.

    My advice to smorg is take your upcoming long trip in your Roadster. Enjoy the drive. You won't hurt anything. my .02
     
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  13. markwj

    markwj Moderator, Asia Pacific

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    For what its worth, I've seen a service manual that gave specific instructions to address inaccuracies in CAC calculation. The range displays in the car are based on the CAC, and that is calculated by a complex algorithm driven by a a feedback-loop. The notes say that the method doesn't increase CAC overnight, but will stop the error and correct the calculation. The procedure is (a) Drive down to 60% SOC, wait an hour, (b) charge up to 100% (in range mode), wait an hour, (c) drive back down to 60%, wait an hour. That, at least, is official Tesla advise to their service techs.

    From my point of view, I think that SOC MIN and MAX are the most important (and the spread between them). Keeping the battery balanced (aka leaving it plugged in after a full standard mode charge) is the most important thing. Once something goes wrong with the battery (some part fails), it shows up earliest as an increasing spread between SOC MIN and MAX. Try to keep them less than 3% apart.
     
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  14. smorgasbord

    smorgasbord Active Member

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    Great info. My question remains whether this is something actually worth doing given that I have no issues, don't currently need to push the range usage on my vehicle, etc.? Or, whether I should just continue to use my car, which I drive multiple times a week for ~50 miles a day (two ~25 mile trips) and continue to have fun and not worry?

    My question was prompted by the opportunity to drive a distance tomorrow morning for a purpose, instead of just to get my CAC recalculated.
     
  15. smorgasbord

    smorgasbord Active Member

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    My question was prompted by the opportunity to drive a distance tomorrow morning for a non-Tesla purpose, instead of just to get my CAC recalculated.

    Great info. My question remains whether this is something actually worth doing given that I have no issues, don't currently need to push the range usage on my vehicle, etc.? Or, whether I should just continue to use my car, which I drive multiple times a week for ~50 miles a day (two ~25 mile trips) and continue to have fun and not worry?
     
  16. hcsharp

    hcsharp Active Member

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    Has anybody given you a reason not to drive your Roadster tomorrow? It seems to me like you have nothing to lose and a small benefit of a more accurate range calculation when you are all done (which you don't really need, but won't hurt).
     
  17. smorgasbord

    smorgasbord Active Member

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    Well, doing the procedure means driving a bunch, then a full Range charge, then driving again - all on a relatively tight timeline. Plus, Range charging when not really necessary probably isn't the best thing I can do to the battery.
     
  18. bolosky

    bolosky Member

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    Meh. I think that the damage caused by a range charge is pretty minimal. While doing it every day probably isn't a good idea (which is why they have standard and range mode at all), once in a while is no big deal. And at least with the 3.0 battery, there's pretty good evidence that the CAC algorithm really needs to see the battery at full range charge and low SOC occasionally in order to get the data it needs to be accurate.
     

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