Newbie bought a gen 2. What modules to replace?

Discussion in 'Gen 2 Prius Technical Discussion' started by Norbie, Feb 6, 2026 at 5:15 PM.

  1. Norbie

    Norbie New Member

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    My son and I recently bought a 2007 with a battery problem. Here are the numbers. What shuld we replace? (see attachement, red ones seem lith the obvious ones!)

    There are so many videos to measure all this stuff but non say "if it measures this, replace it!". We're not doing a mAh capacity test so please don't ask.

    Thanks in advance!
    Brad
     

    Attached Files:

  2. dolj

    dolj Senior Member

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    How did you come up with the IR and percentage health numbers?
     
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  3. Norbie

    Norbie New Member

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    I used the Viking battery tester from Harbor Freight for both IR and health. Used a voltmeter for voltage.
     
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  4. PriusCamper

    PriusCamper Senior Member

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    Just replace module #20 with a replacement from: Oregon's Trusted Hybrid Battery Supplier: 2nd Life Story

    Replacing the other two would require further testing, charging and balancing to be sure and replacing them sooner than later might create more hassles rather than less because replacement modules need to closely match age and history of existing pack.

    It's ok to not do all the more than a dozen ways to test a module, first step is to get the pack going again and clean up the corrosion in bus bars, wires and ECU.

    In general, the first module you replace without much testing can last a year if you're lucky... Future module replacement will last less and less time and most people eventually get fed up and buy a new pack or professionally rebuilt one.