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Traction Battery Health at 178,000 miles

Discussion in 'Gen 2 Prius Technical Discussion' started by krousdb, Aug 7, 2009.

  1. krousdb

    krousdb NX-74205

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    I will be installing the Enginer.us PHEV conversion next weekend. So as long as I have the back of the car torn apart, I thought I would take a look at my traction battery. I currently have 178k miles on my 2004. In addition to measuring the voltage of each of the 28 modules and checking for corrosion at the terminals, what else should I be doing/looking for?
     
    #1 krousdb, Aug 7, 2009
  2. David Beale

    David Beale Senior Member

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    Clean out any dust/dirt so air can flow efficiently around the cells. There isn't much else you can do to these sealed cells.
     
    #2 David Beale, Aug 7, 2009
  3. usbseawolf2000

    usbseawolf2000 HSD PhD

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    Check the HV battery fan motor to see if it is still spinning good. Clean out the air duct as well.
     
    #3 usbseawolf2000, Aug 7, 2009
  4. krousdb

    krousdb NX-74205

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    Well I am pleasantly surprised to say the least. The ScanGauge showed SOC at 63.5. I measured the voltage of the pack at 218.4V. The individual module readings starting from the passenger side are as follows:
    7.82
    7.82
    7.81
    7.81
    7.80
    7.80
    7.80
    7.80
    7.79
    7.79
    7.79
    7.79
    7.80
    7.80
    7.80
    7.79
    7.79
    7.80
    7.80
    7.80
    7.79
    7.80
    7.80
    7.80
    7.80
    7.80
    7.81
    7.82

    I had expected a few week cells, just due to age and mileage but the consistency between cells just blew me away!:rockon: My hats off to the design team that developed this battery back and the BMS.
     
    #4 krousdb, Aug 8, 2009
  5. usbseawolf2000

    usbseawolf2000 HSD PhD

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    That's within 0.3 Volt. Very impressive for a 5 years old 178k miles HV pack.

    You listed 28 modules. Each module has 6 cells so you can't conclude it until you measure all the 168 cells.
     
    #5 usbseawolf2000, Aug 8, 2009
  6. krousdb

    krousdb NX-74205

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    LOL, I'm not dissassembling my modules! I don't know if that's even possible? :confused:
     
    #6 krousdb, Aug 8, 2009
  7. krousdb

    krousdb NX-74205

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    Some pictures....
     

    Attached Files:

    #7 krousdb, Aug 8, 2009
  8. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I don't notice any corrosion or electrolyte leakage in the photos you provided. Do you see any evidence of this?

    Had the module voltages differed by more than a few tenths of a volt, then a DTC would have been logged and you would be discussing with us how you are planning to replace the traction battery... You are correct that it is not possible to measure the voltages of the individual cells without destroying the module. That is not necessary anyway since you can measure the voltage of each module, and the module is the level at which you would replace individual components, should that become necessary.
     
    #8 Patrick Wong, Aug 8, 2009
  9. krousdb

    krousdb NX-74205

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    No corrosion, cracking, leakage or bloating. Nice and new looking. :D

    What is the threshold for voltage difference before DTC is logged?
     
    #9 krousdb, Aug 8, 2009
  10. tochatihu

    tochatihu Senior Member

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    Thanks for posting the numbers. You've got a pattern all right - higher voltages in the edges, and lower in the middle. The differences seem small, but just as we might guess from the modules having different thermal histories in this arrangement.

    As I recall the delta V threshhold for DTC is quite large (maybe 1.2 V?), but it would happen under heavy charge or discharge when the deltas should be larger.
     
    #10 tochatihu, Aug 8, 2009
  11. krousdb

    krousdb NX-74205

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    Yes, I recognized that pattern also. I assume that it is normal? Outer modules will run cooler due to more surface area for cooling?
     
    #11 krousdb, Aug 8, 2009
  12. FireEngineer

    FireEngineer Active Member

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    I believe the manual states more than 20% between any two pairs of modules as the battery ECU measures them, since the ECU measures pairs.

    Wayne
     
    #12 FireEngineer, Aug 8, 2009
  13. ken1784

    ken1784 SuperMID designer

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    I think the delta SOC is the most important data for the health.

    Ken@Japan
     
    #13 ken1784, Aug 8, 2009
  14. krousdb

    krousdb NX-74205

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    Do you mean the rate of change of SOC compared to a new battery at the same discharge rate? If so, I don't think I can measure that without having a new 2009 to compare with. That might be an interesting exercise though. Anyone out there with a scangauge and only a few thousand miles on thier car that I can compare with?
     
    #14 krousdb, Aug 9, 2009
  15. ken1784

    ken1784 SuperMID designer

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    Hi Dan,

    No. It is one of battery health menu by the expensive Toyota diagnostic scanner (TaSCAN).
    The delta SOC (dSOC) tells us the variances between 14 of pair modules on a pack.
    The next important data is the variances of internal resistance (IR0 to IR13) values for pair of modules.
    So, my suggestions is visit a Toyota dealer and let them do the battery health check using the Toyota scanner.

    Ken@Japan
     
    #15 ken1784, Aug 9, 2009
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