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R80 Battery Suddenly Loses over 100 Miles of Range Overnight (While Parked)

Discussion in 'Roadster' started by Curt, Sep 25, 2018.

  1. Curt

    Curt Roadster Signature #55

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    OK, I know, I should have left my Roadster plugged in while I was gone - but it shouldn't have been a problem.

    I was out of town for a week, and parked my Roadster in a rented garage 10 miles from home. Thanks to OVMS, I was able to monitor the state the whole time.

    When I left, I had SOC 56% and Range 132 miles. Over the course of 8 days, the SOC went down to 54%, and the Range to 127 Miles. So far, so good, and exactly as expected.

    My plan was to leave the Roadster there during the next three days of heavy rain, and pick it up for the weekend. This is where things start to get weird...

    Late last night, Range was still 127 Miles. When I looked during Breakfast this morning, it was 16 Miles!!! There were no messages, and no sign that the car had ever been awake over the past 8 days. The Battery Temperature had slowly dropped from 85F to 73F, and since the PEM and Motor Temperatures hadn't updated since I left it (both still over 100F from the drive), there is no reason to think that the coolant pump had been running at any time.

    By the time I could get to the garage, the SOC had gone to 0%. I plugged in for over an hour at 112V/12A (all that is available), but saw no change during that time. I then unplugged, pulled logs, and plugged in again but now in Range Mode, which showed 4% SOC.

    I dropped off the log files at my local Service Center and went home. Right now, after 4 hours charging, SOC is up to 8%.

    Looking at the logs, everything was very steady until about 3AM this morning, at which point the hourly IDLE records show:

    09/25/2018 03:18:33 | 1537859913 | IDLE | range soc = 53% ESS 21.78C - 22.73C, 3.849V min, 3.868V max, 63 brick min V, 22 brick max V

    09/25/2018 04:18:41 | 1537863521 | IDLE | range soc = 52% ESS 21.78C - 22.74C, 3.839V min, 3.868V max, 46 brick min V, 22 brick max V

    09/25/2018 05:18:47 | 1537867127 | IDLE | range soc = 35% ESS 21.77C - 22.73C, 3.775V min, 3.868V max, 46 brick min V, 22 brick max V

    09/25/2018 06:18:54 | 1537870734 | IDLE | range soc = 32% ESS 21.77C - 22.72C, 3.766V min, 3.868V max, 46 brick min V, 22 brick max V

    09/25/2018 07:19:00 | 1537874340 | IDLE | range soc = 19% ESS 21.77C - 22.71C, 3.736V min, 3.868V max, 46 brick min V, 43 brick max V

    09/25/2018 08:19:08 | 1537877948 | IDLE | range soc = 16% ESS 21.77C - 22.70C, 3.717V min, 3.868V max, 46 brick min V, 41 brick max V

    09/25/2018 09:19:15 | 1537881555 | IDLE | range soc = 16% ESS 21.77C - 22.70C, 3.717V min, 3.868V max, 46 brick min V, 41 brick max V

    09/25/2018 10:19:22 | 1537885162 | IDLE | range soc = 15% ESS 21.77C - 22.69C, 3.697V min, 3.868V max, 46 brick min V, 43 brick max V

    09/25/2018 11:19:28 | 1537888768 | IDLE | range soc = 7% ESS 21.77C - 22.70C, 3.668V min, 3.868V max, 46 brick min V, 41 brick max V

    09/25/2018 13:19:27 | 1537895967 | IDLE | range soc = 8% ESS 23.36C - 24.32C, 3.614V min, 3.888V max, 46 brick min V, 22 brick max V


    The last two show the 12Amp charge starting, but SOC was too low to register in Standard Mode.

    This is a complete mystery to me. I haven't found anything so far in the logs to indicate what happened.
     
  2. mongo

    mongo Well-Known Member

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    Based on the change in the min cell voltage (and no change in the max), it looks like a resistive short in one of the sections.
     
  3. MLAUTO

    MLAUTO Member

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    It is going to be a brick in a very short while. Once the good bricks in the pack are fully charged, there will be no way to keep the bad brick from dropping below minimum voltage. Put it in tow mode now while you still can to make the inevitable tow easier. I hope its still under warranty.
     
    • Informative x 1
  4. markwj

    markwj Moderator, Asia Pacific

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    Looks to be a sudden failure of brick #46. If you have a look at the VDS ESS/SOC screen, you'll probably see a large difference between SOC MIN and MAX.

    Alternatively, in a remote ovms console run 'metric list v.b.health' and that will give you a summary. Probably something like this:

    It might also be helpful to look at 'metric list v.b.' to get all the battery metrics. In particular v.b.soc (last known soc), and v.b.soh (OVMS estimate for overall lifetime health).
     
    • Helpful x 1
  5. Curt

    Curt Roadster Signature #55

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    Slight update...

    I was able to get a 120V/12Amp charge going with the SMC (yellow cable), and have found that it is holding charge as long as the SOC is above 50%. That bolstered my confidence, so I drove it to the local Service Center, where I found that one of the techs had already started a preliminary case because of the rapid battery degradation.

    I know I’ll be waiting a while for results, but at least my Roadster is sitting at the Service Center and hooked up to a little-used NEMA 14-50.
     
    • Informative x 3
    • Like x 1
  6. ICON

    ICON Member

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    Wow, this is very disconcerting!
     
  7. augkuo

    augkuo Member

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    Maybe a rat chewed on a cable?
     
  8. Curt

    Curt Roadster Signature #55

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    Inside the ESS? I don't see how. From the IDLE records in the logs, it seems pretty clear that Brick 46 has suddenly failed.
     
    • Like x 1
  9. MLAUTO

    MLAUTO Member

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    Hmmm. You lost about 45% in 10 hours but then were able to get back to 50% in probably 20+ hours of charging. It sounds like the fuse wire attaching the shorted cell finally melted and the drain went away. Since those wires take 15A to blow, it would have been interesting to see what the temp reading of brick 46 was. I would bet the defective cell was almost ready to explode.
     
  10. mongo

    mongo Well-Known Member

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    Interesting. The charger was not providing 15 amps, so the cell would have had to short strongly enough to pull 15A from the other cells in the brick and quickly enough to avoid draining them first.

    Could it be that there was an internal short that has been (temporarily) destroyed?

    Fast charging or driving and discharging would show whether the cell is gone entirely (brick would unbalance) or if the drain has vanished (bricks stay balanced).
     
  11. Curt

    Curt Roadster Signature #55

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    Another update...

    My Roadster has been at the local Service Center for 16 days, most of the time hooked up to a NEMA 14-50. Each charge cycle, the Standard charge finishes normally, then between charges, the SOC bounces all over the place. When disconnected, the SOC may stay fairly stable for a day or two, then it drops overnight from around 75% to just over 50% and stays around there for a while. Watching from OVMS, I have seen it drop to 46% then recover to 59% over the course of 10 minutes.

    It looks like the plan is to disconnect and let the battery drain, then to replace the entire battery. What kind of battery is still unknown, but it’s likely it will be a used 53kWh battery (along with yet another PEM swap) just to get me back on the road until a real solution is found.

    If they do this, I think I’ll be demanding either a statement in writing detailing how they intend to make this right, or a rather large refund.

    Not happy about this, but I know there are others with worse problems.
     
  12. mongo

    mongo Well-Known Member

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    If SOC is going up as well as down with no load, it sounds like the BMS voltage sense for that brick may be the issue.
     
  13. Curt

    Curt Roadster Signature #55

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    It’s hard to say what the actual problem is, but HQ has at least three log sets now, and the word back from them is just to replace the whole battery, rather than diagnose/fix the problem.
     
    • Helpful x 1
  14. dpeilow

    dpeilow Moderator

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    Have you seen any sort of warranty document during all this?
     
  15. Curt

    Curt Roadster Signature #55

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    Of course not - I don’t think they actually have a document, it’s just a verbal assurance.
     
  16. dpeilow

    dpeilow Moderator

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    I'd love to know how that would go down with a consumer rights lawyer...
     
  17. Curt

    Curt Roadster Signature #55

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    Back again...

    After six months, I have my Roadster back. There has been very little communication, so I really don't know at this point what has been done.

    I know it sat outside the local Service Center for five months, unplugged, and whenever I asked, the response was "we're waiting for instructions from California".

    On 6 March, the Service Center received a shipping crate for the ESS. They pushed the Roadster inside, removed the ESS, and shipped it to California.

    On 3 April, the ESS arrived at the Service Center, and I was able to pick it up on 4 April. I had to go out of town immediately after, so I've only had yesterday to drive it.

    My hope had been that someone had been working for the past several months to solve at least some of the 3.0 issues, but my Service Invoice only says:
    Replaced HV battery, internal fault found.
    Install replacement 3.0 pack, update firmware.
    Check charging- OK

    I'm reading a CAC of 182.81, with 182 Ideal Miles on a Standard Mode charge.

    The work was done at no charge, and I have no word on the Warranty.
     
    • Informative x 4
  18. backmost

    backmost Member

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    Damn mine is still at 200 miles on an ideal charge, CAC @ 175.73. Did they charge you for the shipping of the car?
     
  19. Curt

    Curt Roadster Signature #55

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    I would expect that it will take a few charge cycles before range numbers are accurate.

    They only shipped the battery - no charge for anything.
     

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