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Range Charge

Discussion in 'Roadster' started by Tesla 940, Dec 26, 2012.

  1. Tesla 940

    Tesla 940 Member

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    #1 Tesla 940, Dec 26, 2012
    Last edited: Dec 26, 2012
    I know there is/was a thread about this somewhere but hell if I can find it.

    I charged my Roadster in Range mode this weekend and the vdo showed range of 241 Ideal Miles. I let is sit for 2 1/2 hours and it dropped to 231 Ideal Miles- then "topped off" and it went to 233 Ideal Miles. The car is 2 1/2 years old and has ~ 12,000 miles. I was charging at 40/240.

    I was a little surprised by the 241 and then the drop to 231 in 2+ hours.

    Any thoughts?

    Moderator - feel free to move to the appropriate thread.

    Thanks,
    Don
     
  2. Doug_G

    Doug_G Lead Moderator

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    The Roadster performs battery pack balancing when you leave it for a while after a range mode charge. This burns off a little energy. It is actually a good thing for the health of hour pack. If you need a little extra range afterwards then hit the top off button.
     
  3. wiztecy

    wiztecy Active Member

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    #3 wiztecy, Dec 26, 2012
    Last edited: Dec 26, 2012
    Range mode will begin "bleeding" off the charge right after you're finished charging to protect the battery for longevity. I have never found the "Topping off" to do anything good really and you may even stress the cells more by doing that, especially doing 100% charges. If you charge in Range mode you are to unplug it and GO! Thats how you get the max range out of it. And I was told this from Tesla. Its opposite of your standard mode charges where you should allow 30mins to 1hour for the pack to fully balance itself before you drive off. The bleed process will keep going until you get down to the 85% range, which is approx std. mode charging ends. My last Range mode charge, when finished charged up to 249 ideal miles. After 15-20 mins I settled down to 235 ideal miles, I have 13,500 miles on the Roadster and it came alive in April 2009. I then let the pack sit for the weekend to see if I can "balance" or equalize the pack. It didn't buy me anything except I watched my ideal miles bleed down to 191 ideal miles after 2-3 days. Even Tesla said my pack had nothing for them to do and was very well balanced. This is most likely for the fact I wait 30-60mins after each of my std. mode charges for pack balancing.

    Note that after you do a range mode charge it was suggested to me by Tesla to bring the pack down to 40-45% so that the pack can balance back up in its next charge otherwise you may not get the full ideal miles / potential from your following charges.
     
  4. hcsharp

    hcsharp Active Member

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    I'm not quite sure what your questions are. Perhaps you can be more specific. Not every cell is charged or discharged exactly evenly. To fix this, the pack will attempt to balance the state of charge between cells after a charge. It does a little more balancing after a range charge than a std. It also runs the circulator constantly after a range charge to prevent the cells from the damage that comes from sitting at a high state of charge. I don't know why topping it up didn't bring it up to 241 miles again.
     
  5. bolosky

    bolosky Member

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    This isn't bleeding or balancing or anything like that, and the car does not quickly drain from range mode down to 85%. All that's happening is the same thing that happens right after many standard mode charges: It takes the car a little while to figure out how much charge is actually in the battery, and the ideal miles will go down as it does this. If you were to start driving right after charging when it said 241, what you'd see is that the ideal miles would drop off very rapidly in the first couple of minutes, probably down to the 230-something that you got by letting it sit.

    There is some battery balancing that happens, particularly when it's charged in range mode, but it's pretty slow and shouldn't reduce your range anyway.

    So...don't sweat it, but don't believe the 241 number, either.
     
  6. wiztecy

    wiztecy Active Member

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    #6 wiztecy, Dec 26, 2012
    Last edited: Dec 26, 2012
    It takes my Roadster only 15 minutes to settle down on its correct range... In Std. Mode, 15 minutes and it holds that number for a long time, only loosing 1-2 miles over the course of 3-4 days. In Range mode almost the same, 15-25 mins and it settles into the range and then it is bleeding like Henry said running the cooling pump, I believe not allowing the car to sleep to drain down the pack. So you will see your range drop after 2 hours from the bleed, you won't go to 85%, that will happen after 2-3 days. I didn't see it drop below that so that must be the number they're targeting that's the safe zone for the pack.

    After you disconnect and drive your roadster it will drop fast like bolosky indicated, the roadster is still allowing the pack to settle in to more accurately calculate its correct range.

    One thing you need to add to your scenerio is the time lapse and drop off in range. Was it after the 1st 30 hour that your range dropped from 241 to 234 ideal miles and then the last 1.5 hours it went from 234 down to 231? If so that sounds normal.

    Time crossed with ideal miles is crucial in identifying the true behavior of your pack
     
  7. Tesla 940

    Tesla 940 Member

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    Thanks for the responses.

    I was a little surprised by the drop from 241 to 231 - which was more than I expected. I was also surprised that "topping off" only got me from 231 to 233 - I was expecting a little more.

    Thanks again for the responses.
     
  8. wiztecy

    wiztecy Active Member

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    Tesla 940, can you elaborate on how many miles your roadster dropped within the 1st half hour and hour time-frame. This will help others understand the behavior of the charge when they read the post. Since your Roadster topped off at 233, after the pack equalized, makes me believe that the 1st half hour and hour most likely dropped down to the 235 mile range.

    Is this your first range mode charge? If not, what was the range mode behavior before if you recall?
     
  9. djp

    djp Roadster 2.0 VIN939

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    I've seen a similar drop-off on Standard mode charges as well. On Tuesday I charged to 220km ideal, stopped the charge, and within two hours it was down to 192km. Don't trust the range numbers immediately after a charge.
     
  10. dhrivnak

    dhrivnak Active Member

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    Having built a few EVs with lithium batteries you find the batteries develop a "surface" charge at the end of a charge cycle where the voltage is higher than normal and is scrubbbed off by running an acccessory or giving some time for it to wear off. So I am not surprised at all to see the range change, inaccurately, just after a range charge. It is not so much a problem as a quirk with lithium batteries. While Tesla's range predictions are second to none I have not found them to be totally accurate, at least not down to the last 10 miles for a full range estimate.
     

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