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Hybrid battery change?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by GETAKLU, Sep 13, 2019.

  1. GETAKLU

    GETAKLU Junior Member

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    Ok, tore into the batteries and put a multi meter on them. The 2008 has 24 good cells that are all really close in voltage. The 2004 has about 9 cells that are showing promise, but they range from 05.8 to 07.1 volts.

    What would y’alls recommendation on replacing the bad cells in the 2008 battery with the highest volt cells out of the 2004?
     
  2. GETAKLU

    GETAKLU Junior Member

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    The first is the 2008 and the second is the 2004.
     

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  3. JC91006

    JC91006 Senior Member

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    Dude those measurements are useless, you have to charge the battery, rest it for a week, then retake measurements.

    Taking on a task like this without the right equipment is like going to play tennis with a racquetball racket. Will it work? Maybe, but it won't work very well
     
  4. GETAKLU

    GETAKLU Junior Member

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    I don’t see why they are useless, volts in a battery are volts in a battery. Anyway, I tore down my 2005’s current battery and found every cell is registering between 8.0 and 8.1. This is after I went out on a drive and charged the pack up to the second to the top bar.
     

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  5. JC91006

    JC91006 Senior Member

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    OK, I guess you should proceed with that belief. You probably won't get very far though

    You'll find that batteries that measure good (7.2v or higher) will often fail under a load test. Which makes them useless, even though the voltage reading will say otherwise.

    Also looking at the car's battery state of charge on the screen will not tell you if the battery is charged, it measures the weakest battery module (block) and the strongest battery module reading only, out of the 28 in the car.

    Again, don't proceed with what you're doing without the proper equipment....and knowledge
     
    #25 JC91006, Sep 18, 2019
    Last edited: Sep 18, 2019
  6. jerrymildred

    jerrymildred Senior Member

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    And internal resistance is internal resistance. That's just as important and you still don't know how that property compares. @JC91006 probably knows more about these batteries than both of us put together. I'd pay close attention to his advice.
     
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  7. JC91006

    JC91006 Senior Member

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    Thanks for the kind words. I know there are much more knowledgeable folks on this forum that will try and help him. I just don't want him wasting all his time and getting really bad results with his work.
     
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  8. TMR-JWAP

    TMR-JWAP Senior Member

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    From OP #1

    The current hybrid battery has not given me any problems yet,

    so why tear into it? There are so many apps available to test it while it's installed. Are you a glutton for punishment?

    And on a side note....the static voltage of a used module in no way, shape or form is an accurate indicator of it's actual energy storage capacity.
     
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  9. jerrymildred

    jerrymildred Senior Member

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    And one just showed up right after you said that. :) There are a bunch of really knowledgeable Prius peeps here. It just takes a while to sort them out.
     
  10. GETAKLU

    GETAKLU Junior Member

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    What apps and what equipment do I need then?
     
  11. TMR-JWAP

    TMR-JWAP Senior Member

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    Take a look at Hybrid Assistant / Hybrid Reporter. Purchase a quality Bluetooth OBD adapter as recommended by the HA/HR website.

    You can test the HV battery just by running the AC system. After the test, the Reporter app can display all the info in easy to read graphs.

    Like this:

    Just Another HV Battery Thread and Experiments | PriusChat

    When you look at the 14 lines (one for each of the 14 blocks) a 100% perfect HV battery would have all 14 lines on top of each other and it would look like a single line. Since no battery is perfect, they will all be slightly different. What you're looking for are outliers. The HV battery will code out if there is a significant difference between the highest and lowest voltage value. This is why it doesn't always make sense to put a brand new module into a pack full of old modules. Having one module that holds a high voltage is almost as bad as having one module that drops quickly. The goal is to have 14 blocks (28 modules) that all have similar discharge characteristics so the 14 voltages remain close.

    When driving the car on relatively flat areas, the car doesn't care if the battery has 6.5aH capacity or 2 aH capacity. There will be little to no difference in how the car drives.

    Start getting into hilly areas, low capacity batteries will be more noticeable, as less power will be available for those upgrades.

    Lower capacity batteries will also be more noticeable when using AC, as the engine will run more often to maintain the battery charged up. Mostly noticeable when sitting in traffic or stoplights, etc.
     
    #31 TMR-JWAP, Sep 20, 2019
    Last edited: Sep 20, 2019
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  12. Skibob

    Skibob Senior Member

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  13. dolj

    dolj Senior Member

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    I would read only the first couple or three pages of that thread, then skip to about page 60, then just skim posts for relevant info then when you get tired of that skip to the last five or ten pages.

    One technique that is mentioned in that thread which is now considered a waste of time and effort is that of "equalising the pack". This involves connecting all the +ve terminals together in parallel and (separately) all the –ve terminal together in parallel and letting it sit for a long period of time (24 hours+). This has been proved to do nothing useful, so scrub that from your list of things to do.
     
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