Assessing overall HV battery health

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Epiphany2000, Apr 20, 2014.

  1. Epiphany2000

    Epiphany2000 Member

    Joined:
    Dec 23, 2013
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    Location:
    San Francisco Bay Area, CA
    Vehicle:
    2005 Prius
    Greetings everyone,

    I have a 2005 Prius with 70k miles (purchased from private party last December with 66k miles). I reside in Sonoma County, CA, where the weather is relatively temperate (see attached chart of average highs and lows throughout the year).

    Average temperatures.png

    Although the likelihood of having an HV battery failure at this point is low, I’d like to assess the battery’s overall state of health. If nothing else, this I’d like to establish a baseline to measure against in case I have problems in the future.

    Based on a 45 mile trip a couple of days ago, I compiled some data regarding the voltages of the individual battery blocks. With 3,384 rows of data, here’s what I came up with…

    # of instances each individual battery block reported the lowest/highest voltage:

    Block Voltages.png

    Difference between highest and lowest battery blocks:
    Mean: 0.178716612 volts
    Median: 0.17 volts (kept it to 2 decimal places in order to get a meaningful figure)

    Clearly, block 0 had the highest voltage most of the time, with block 13 coming in a distant second.
    Block 10 most commonly had the lowest voltage, followed by blocks 11 and 8.

    Questions:
    Do with these numbers, do I have any reason to be concerned?
    At what voltage difference between blocks should I become concerned?
    What other data should I collect/compile in order to assess the health of my HV battery?

    Any feedback/suggestions would be greatly appreciated.

    Thanks!
     
    #1 Epiphany2000, Apr 20, 2014
  2. slimothy

    slimothy Junior Member

    Joined:
    Feb 13, 2014
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    Location:
    Seattle, WA
    Vehicle:
    2010 Prius
    Model:
    III
    A couple things you may want to filter your data on:

    See how the battery blocks perform when they have high in/out currents (there's going to be lots of data points without a lot of load on the battery blocks, this filters on the high stress cases)

    And in those cases, see if block 10 generates large deviations from the highest voltage block relative to other modules, or if it's just marginally lower than other blocks, just happens to be a tiny bit lower voltage wise.

    You may need to collect more data points to get enough sampling (or just to capture the HV current pids).
     
    #2 slimothy, Apr 20, 2014
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