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Evaluating battery condtion on 2008 Roadster - hopeful buyer needs help!

Discussion in 'Roadster' started by dgh, Aug 31, 2014.

  1. dgh

    dgh Member

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    I am trying to understand the condition of a battery on a 2008 Roadster I am hoping to purchase from a private seller.


    As background, the car has about 3,000 miles but no warranty. I am working on getting service records, but other than the battery questions below, all indications are that the car is in great shape.


    I am confused about the information I have gotten on the battery from the seller. My confusion stems from the different charge modes of the Roadster that the seller has given me screen shots of (see below). I did try researching different modes, but I am still confused. Some help would really be appreciated!


    Here are the screen shots: (I was told the battery was between 95-98% SOC)


    First: Range Mode - Ideal setting - 208 miles


    jpg.gif


    Second: Range Mode - Estimated rate -146 miles


    jpg.gif


    Third - Max Range mode - Ideal setting - 233 miles


    jpg.gif


    Fourth - Max Range mode - Estimated rate - 164 miles.


    jpg.gif


    My main question is do these readings reflect a Roadster with a healthy battery at 6 years, 3,000 miles. Does the 233 reading in "max range" mode simply get compared to 245 miles a brand new Roadster would have gotten fully charged in range mode? Is it more complicated than that? Is it the 208 mile "Range mode Ideal" reading that really gets compared to 245 miles for a new Roaster (I'd never heard of "Max Range" before getting these screen shots, and I'd never heard of anyone describing two different readings over 200 miles). Is there anything inconsistent in the four readings in the pictures emailed to me... if anyone is willing to take this on, an explanation of the four readings would be appreciated.


    I am interested to hear what people here at TMC think. I realize I could pursue this question with Tesla service (and I am trying to do this) but there is a complicating factor with that so hearing from your experience would really be appreciated.
     

    Attached Files:

  2. AEdennis

    AEdennis Active Member

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    Grab the logs... There are instructions on how to configure a 1Gb or 2Gb USB drive with a special folder (have to look it up).
     
  3. markwj

    markwj Moderator, Asia Pacific

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    Have a look at the background information here:

    http://www.pluginamerica.org/surveys/batteries/tesla-roadster/PIA-Roadster-Battery-Study.pdf

    You can ignore 'estimated' (dependent on recent driving history) and just concentrate on 'ideal' miles (which tracks the battery pack itself).

    As AEdennis says, the best is to pull the logs themselves and have a look at how each brick in the ESS is doing. Make sure they are all about the same levels, and nothing too high/low.
     
  4. Mark77a

    Mark77a Member

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    Telsa-Roadster-Battery-Pack-Figure-1.png

    Above is a graph from the Survey Mark Suggested - as you can see 'your' car looks good with a range of 233 miles (fully charged in range mode) .. the other screen shots are not as helpful
    It would be reasonable to ask the owner for the log files, which expand on this and show the recent driving history and a figure called CAC which is also a good indicator.
    But CAC is directly related to ideal miles in either range mode or standard mode ..

    ... if you are like me when collecting info for checking out cars ... you can say goodbye to several evenings !! .... searching and scanning roaster related threads on here :smile:
     
  5. dhrivnak

    dhrivnak Active Member

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    In a word it looks like you are fine. I have a 1.5 Roadster that has done well for 27,000 miles and I get 224 ideal miles in range mode and you car is sitting at 233. So I think you are good to go.
     
  6. wiztecy

    wiztecy Active Member

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    Also if this Roadster has been sitting, most likely it has to be some CAC and possibly pack balancing that'll work in your favor after you start doing some long trips with it. Meaning that your range may start climbing if the CAC gets recalculated and is higher.

    Whats odd is its at 0ft elevation and 100 degrees.

    Kinda hot, was that pic taken outside? Close to the beach, but chances at being at 0ft is not common.... but why is it so hot unless its in the dead heat rays of the sun. Usually this heat sensor is overly rated but its still getting baked.
     
  7. dgh

    dgh Member

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    thanks for all the feedback.

    233 miles as a pretty healthy battery makes sense to me except for one nagging question... why is there a reading for both "Max Range" Ideal (the 233 miles) AND a reading for Range Mode Ideal of 208 miles as you can see in the last photo (the small photo).

    I have never seen any mention of "Max Range" for a Roadster. Not in the PDF of the Roadster manual I found, not in Tom Saxson's paper (nor the form he created for people to enter their Roadster battery data), not in a few years of lurking on TMC, and not searching for the term here on TMC in regards to a Roadster (though, to be fair I've not been exhaustive in checking through that yet... lots of Model S entries).

    What's more I have never seen any mention of two different range mode ideal readings, nor have I ever seen a pair of different readings for a Roadster over 200 miles. The Saxson paper just underscores this... there's range mode ideal readings basically in the 220-240s, and standard mode ideal readings in the 170-190s. Which number, 208 miles or 233 miles, is the apples to apples comparison to 245 miles when the car was new?

    I kind of wonder if the 233 "Max Range" Ideal isn't based on some arcane setting that's not a fair comparison to what is commonly understood to be Range Mode Ideal.
     
  8. markwj

    markwj Moderator, Asia Pacific

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    The picture with "max range" in the green battery is just RANGE mode. The picture with nothing in the green battery is STANDARD mode.

    If you tap the green battery, you switch between modes. There is also PERFORMANCE mode, and even a STORAGE mode (set in the charging menu of the VDS) to further complicate things.
     
  9. slcasner

    slcasner Member

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    As markjw said, the words "Max Range" overlaid on the battery symbol indicate that Range Mode has been selected. You write "Range Mode Ideal of 208 miles", but the phrase "Range Mode Ideal" does not appear anywhere in the display. Rather, the display shows "IDEAL RANGE" underneath the 208 value. That is not an indication of Range Mode, it is an indication of ideal (EPA) range versus estimated range. If you touch the Range circle underneath the 233 or 208 number then the display will toggle to EST RANGE and show the estimate of range that considers recent consumption.

    The 233 number corresponds to the 245 number. The reason for the 208 reading is that the car was changed to its maximum capacity in Range Mode, which means that the top 10% or so of the batteries capacity is filled, whereas that is not the case for Standard Mode. Then for the picture showing 208, the mode was toggled to Standard by tapping on the battery symbol. That reduces the available range by not allowing the bottom 10% of the battery to be used, which is 25 ideal miles, but since the battery is more full than it would be if charging had completed in Standard mode, the ideal range number is higher than the 170-190 span. If you look carefully at the battery symbol, it is all the way to 100% rather than the 95 or 96% that is normally the case, as in the picture with 233 miles. The battery symbol actually needs to show about 107% according to my calculation for my car when in this condition. The funny business with battery % readings is because when in Standard mode the level is scaled so that 0-100% represents the 10% to 90% portion of the full capacity that is utilized. I would have been happier if Tesla had not implemented this scaling and just shaded the top and bottom 10% of the battery bar, or something like that.

    Nope, the 233 is the Ideal Range in Range Mode, and as has been stated, that is a good value. My VIN 33 with 33K miles gets 226 corresponding to your 233 and 201 corresponding to your 208.
     
  10. wiztecy

    wiztecy Active Member

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    One important point is ask the seller how long did he wait until he took the VMS display pics in Range mode. The Roadster starts bleeding the charge immediately after its completed to alleviate the pack from stress. If this was hours after the pack's been charged you're even in a better situation. Usually Range mode charge numbers are taken after its done charging. And really that's what you should be doing, as soon as a range mode charge is done you should be driving off. Packs don't like being at 87-100% SOC nor 0-17% for any periods of time.
     
  11. hcsharp

    hcsharp Active Member

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    If you charge this car full in range mode it will read 233 miles. If you then switch it to Std mode it will read 25 miles less, which is 208 miles. That's where that came from. slcasner explained it pretty well above.
     
  12. dgh

    dgh Member

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    thanks for all the replies. slcasner I appreciate your taking the time to go over all those details.

    I had been thrown by the word "range" in the circle at the bottom in all the screen shots combined with the fact that the word "standard" didn't appear in any of the shots. I had taken that circle with the word "range" in it to mean all these readings were in range mode. Now, I'm pretty sure I got it... that circle with the word "range" doesn't have anything to do with what mode the battery is charged in (I guess it just tells you you've chosen a screen view that has information about the Roadster's range). "max range" in the green battery bar is what indicates range mode, nothing in the battery bar indicates standard mode. (and the 208 reading is sort of a hybrid... battery filled up as high as range mode, but car set to operate in standard mode (not use last 10 percent at bottom of battery, and if I understand correctly not allow as much demand on the battery during acceleration...)).

    - - - Updated - - -

    good catches wiztecy. The high temp where the photo was taken that day was 72. The elevation in the town is between 0 and 50 feet, so if the display is by 100 feet, it's a fair reading. Temp does seem high... I figured the car was sitting in the sun, but 100 does seem like a high and rather round number.
     
  13. wiztecy

    wiztecy Active Member

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    I don't know exactly where the temp sensor pickup is, something tells me in the front, possibly under a fender and its very inaccurate whenever sitting out in the sun, even driving down a very hot tarmac will set it off. I know if I'm driving out on a day that's in the 90-95F range, the temp sensor will say its 110F. Good to know he's around sea-level, so all these readings make pretty good sense.
     
  14. slcasner

    slcasner Member

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    The circle with the word RANGE just indicates that it is a button that you can touch, and its function is to toggle the display of remaining range between IDEAL RANGE and EST RANGE. It is labeled RANGE because its function is to choose which measure of range you want to see. As you've realized, it has nothing to do with the mode in which the battery was charged (except that the range numbers displayed will be larger when the charging was in Range Mode, of course).
     
  15. jackbowers

    jackbowers Jack Bowers

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    In range mode the display shows 100% of the battery range and if you are charging the pack will be charged full. In standard mode the display hides the lower 25 miles and the pack is charged to the 90% point (unless you first charge full in range mode then switch to standard, as is the case here).

    When driving in range mode (which cuts the drivetrain power by 50%), I try to avoid driving in the lower 25 because a Tesla engineer once told me, "we really don't know the true pack capacity in the bottom 10% of the battery's range." Once when I had to do it the car blanked out the numerical display of miles and showed only a diminishing red bar. At roughly the 10 mile point, it began firing "Charge Now" warnings, which meant I was very close to running out.
     

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