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Battery range issue

Discussion in 'Roadster: Technical' started by bart513, Jun 3, 2013.

  1. bart513

    bart513 Member

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    I've noticed a small drop in the "ideal range" on my 2008 Roadster. When I got the car at the beginning of April the ideal charge was about 180-185. Now it's dipped down to 175-179. Any ideas and could it possibly be the warmer temperatures? Would putting it in Range Mode be helpful?
    Thanks
     
  2. Raffy.Roma

    Raffy.Roma Active Member

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    @bart513

    A TMC friend told me that charging in Range Mode once per month it's like an antibiotic for the battery. It helps to balance the battery. But for the time being I have not the Roadster, so I think that you'd better get the confirmation of this circumstance by a Roadster owner.
     
  3. wycolo

    wycolo Active Member

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    Mileage on this bad boy??
    --
     
  4. bart513

    bart513 Member

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    17K and loving every mile!
     
  5. djp

    djp Roadster 2.0 VIN939

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    175-179 ideal for a 2008 Roadster with 17,000 miles sounds about in line with other Roadsters the same age/mileage.

    Did you recently do a road trip? The capacity calculation is recalibrated when you do a single long drive without turning the key off. This could have reset the ideal range estimate and brought it back in line with the actual capacity after being overestimated in April.

    You could also try a Range charge to rebalance the pack, but that shouldn't be an issue if you've been charging in Standard mode.
     
  6. hcsharp

    hcsharp Active Member

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    It used to be that charging in range mode and then letting it sit for a few hours was a good thing about once a month to help balance the pack. It's still not a bad idea but you don't need to do it as often because a firmware update a year or two ago allowed some balancing after a std mode charge on 240v.

    +1 to what djp said. It seems like you lose range in sudden drops but usually it's a result of the system recalculating after a long trip.
     
  7. Alan

    Alan Member

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    185 is good / on the high side so as others have said it may have recalculated and the 175-179 may be the true figure.

    Suggest you allow the battery to discharge down to a fairly low level - say 30m ideal in normal use if possible. This gives the electronics a chance to calibrate at the low end. Next do a range charge leaving the car to settle (balance cells) after the end of charge for several hours.

    Use the car for a few days then do a standard charge, leave for a couple of hours and take a note of the reading again it should be a true figure.

    In my experience charging from lower power sources (for me 13A @ 240V) gives 2 or 3 more miles per charge than 30A @ 240V. Warmer weather seems to add a couple more miles as well.
     
  8. Alfred

    Alfred Member

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    Normally these changes (up or down) simply signal that charging has stopped on another brick. The logs can tell you the number of this brick. When charging in standard mode it is good to leave the car connected for a couple of hours more to give it time to do some balancing. In my case range mode charges had no influence on where the charge stopped later in Standard Mode, but a longer drive to perhaps down to 100 Km left in Standard Mode, has led once or twice to a change of the charge-stopping-brick, resulting in an up or down revision of range. As others mentioned, charging more slowly probably stops the charge a bit later and a few Km more apparent range are shown. You will find more information here in the threads relating to the log parsers as e.g. in this thread. Your 179 miles is a very typical figure and small changes are no reason for concern.
     
  9. Raffy.Roma

    Raffy.Roma Active Member

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    Nice. I didn't know this. Thank you.

    - - - Updated - - -

    The same as I said to hcsharp. Thank you.
     
  10. mg012

    mg012 Member

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    So, I've heard that the battery doesn't like the extremes, almost zero or 99-100%. I drive my roadster about 5-10 miles per day with occasional trips of 50-80 miles. This means that I rarely need the battery to be ready at 95% (where it goes from Standard Charge).
    How often should I charge my car, ideally? Let it get down to 20%, 30%, 50%?

    Thanks
    michael
     
  11. djp

    djp Roadster 2.0 VIN939

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    #11 djp, Jun 4, 2013
    Last edited: Jun 4, 2013
    My use is similar to yours, generally 5-10 miles per day as a daily driver and the occasional 100 mile day on a weekend.

    My max charge during the week is 50% and I recharge when it drops to 35% (usually once a week). If I need more range I'll do a Standard charge the night before or top up that morning.

    In general low SOC and cool temperatures are best for battery life. However it's tougher to draw power at low SOC and the Roadster limits power below 15%, so I'd stay out of that range for regular use.

    Here are the battery degradation curves from the NREL study (Model S chemistry, but the studies on Roadster chemistry are similar):

    View attachment 23060
     
  12. wiztecy

    wiztecy Active Member

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    #12 wiztecy, Jun 4, 2013
    Last edited: Jun 4, 2013
    Bart, what's your CAC? The ideal miles is not as accurate as the CAC calculation. I heard that the CAC does not change all that much, meaning that's the true health of the battery pack. I also heard... keeps changing that there's two ways the pack gets recalibrated.

    1) The balancing - this usually is needed when the pack has not had a change to do full std / range modes, meaning that it was charged multiple times below 80% SOC and taken on drives... such as long trips with short charges that didn't allow the pack to balance.

    2) Driving down the pack 30% from 80%+ SOC on one key turn - I've heard multiple versions of this one... meaning driving the pack down to 30% from 80%+ SOC or consuming 30% of the 80%+ SOC on one key turn... so if you dipped down to 70% SOC from a 100% SOC, cycled the key off/on say stopping off at the store then came home (cycled the key off) and charged then calculation / calibration will not happen. Thiss the latest I heard on the 30% (re)calculation. I've been asking for clarification on this and some documentation on how to care for the pack from Tesla but haven't had any luck. I don't know why this is such a grey area....

    As for Range mode charges, Tesla told me to limit my Range mode charges as much as possible. But others believe it may help the pack. I do believe in keeping the pack closer to a 50% SOC and only use Range mode charges to balance a way out of balanced pack faster or when doing a long drive, but with that long drive, I make it a point to drive off as soon as the charging has completed to pull the SOC down to avoid some stresses.

    I've also seen my CAC jump around one CAC and recover which would correlate to loss and recovery of ideal miles.

    Best way to understand the true health of your pack is to dump your logs and run them through the VMSparser command line tool or Doug's Parser. This will output your CAC as well as your average and lowest brick AmpHour so you can see if there's a brick that's pulling the rest down. Your strongest brick will only charge/supply as much capacity as your lowest brick... or it may be the average of all the bricks which is limited by your lowest brick.
     
  13. bart513

    bart513 Member

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    I have to read the forum post on the VMSparser to get the CAC number. I fully charge the car in Standard mode and drive about 140 miles one way to work leaving me about 26 miles or so depending on how I drive. Then at night I plug it in and it gets a full charge and I drive it about 30 miles, do the same the following night and day. Then drive it back home another 140 miles where I charge it overnight. Weekends I drive it about 50 miles/day and charge it at night.
     
  14. Andrew Wolfe

    Andrew Wolfe Roadster 472 - S 440

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    I get 177 or 178 in standard mode. 2008 with 13.5K miles.
     
  15. wiztecy

    wiztecy Active Member

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  16. bart513

    bart513 Member

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    Thanks Andrew for normalizing the range and thanks big D for the link!!!
     

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