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Hv battery question

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by tintmanpa, Sep 4, 2017.

  1. tintmanpa

    tintmanpa Junior Member

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    I got a 05 prius with a battery code. I drove the car till the battery was charged almost to full one bar short

    I then pulled the hv battery and checked the voltage of each cell. Most were between 8.00 and 8.05. Two were 7.95
    One was 6.74
    I am going to replace cells so I need one or three?
    And can I just replace them and let the car cycle the new cells into the pack. Thanks in advance
     
    #1 tintmanpa, Sep 4, 2017
  2. dolj

    dolj Senior Member

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    Hi and welcome to PriusChat.

    Be prepared to spend a while doing this job.

    You need at least three modules (you can't check cells as there are 6 cells to each module and each module is a sealed unit), maybe more.

    Before you order any modules, you need to charge up each of your existing modules and then apply a 10 - 15 Amp load for 2 minutes and note the starting and ending (at the 2 minute mark while still under load) voltages. Subtract the ending voltage from the starting voltage and record the difference. This will highlight the modules that are out of step with the others in your pack.

    What you are looking for are modules that have a significantly higher difference than the rest. Discard those. Most likely the three you found already and maybe others.

    Now the fun part, you need to purchase replacement modules (try and stick with 2005 modules) and perform the same charge and load test on them and use only modules that have the similar voltage difference as the others in the pack that you are retaining.

    Finally, rebuild the pack and grid charge/discharge for three cycles.

    If you do this, you have the best chance of the pack lasting may be 6 months, 1 year, 2 years, 3 years, who knows how long?

    If that doesn't appeal, buy a pack from a late model Gen III wreck and transfer all the modules from that pack to your Gen II case.

    You may be able to cut corners and you may get lucky.

    All the best.
     
    #2 dolj, Sep 5, 2017
    Last edited: Sep 5, 2017
  3. tintmanpa

    tintmanpa Junior Member

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    Thanks.
     
    #3 tintmanpa, Sep 5, 2017
  4. tintmanpa

    tintmanpa Junior Member

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    I meant modules
     
    #4 tintmanpa, Sep 5, 2017
  5. tintmanpa

    tintmanpa Junior Member

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    So I changed 3 modules. All the lights went out except the red triangle ! Light which I now find out has been on for 5 plus years and the previous owner had covered with black tape. But my hv fan is now off and all seems well. The other light that is on is a head light adjustment which appears on the information screen.
     
    #5 tintmanpa, Sep 11, 2017
  6. jadziasman

    jadziasman Prius owner emeritus

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    Oh boy! You just happened to NOT notice a piece of black tape?????

    And, a big piece of tape is needed to cover the triangle of death. Wow.
     
    #6 jadziasman, Sep 11, 2017
  7. Fredsimm

    Fredsimm Active Member

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    Please tell us the method that you followed and if you omitted any steps. Some are just changing the modules without load testing or grid charging. Let us also know the endurance of your hv pack so that we can learn from your experience.
     
    #7 Fredsimm, Sep 11, 2017
    tintmanpa likes this.
  8. jadziasman

    jadziasman Prius owner emeritus

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    I'd wager "whack a mole" repair. But to be fair, tintmanpa did not tell us what he did. To swap out three modules in less than a week's time screams WAM to me without a 200+VDC power supply.
     
    #8 jadziasman, Sep 11, 2017
  9. tintmanpa

    tintmanpa Junior Member

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    Lol. No wam. I replaced 3 modules. Every thing came out good and went back together with no problems. I did disassembled all the modus the furthest one out was one of the 3 I needed to switch. It is running fine

    I still had the triangle of death and the headlight level light in. I found the switch above the rear axle was rusted solid. And the bracket the fits over the key in the switch snapped. I was able to weld the bracket and I got a switch from eBay for 18 bucks. Hooked it up and no more lights. The total fix for the 3 modules was $105 the switch 18. I did also replace the plug on the leveling switch from a junk yard Toyota egr valve plug. The wires are different colors so it had to be matched up correctly. Plug was a buck. Thanks prius chat. And thanks you tube.
     
    #9 tintmanpa, Sep 28, 2017
  10. tintmanpa

    tintmanpa Junior Member

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    I didn't load test or grid test. My 3 replacements were all close to the modules I considered good. If I have any issues I'll keep you posted. The guy I got them from said he has 4 priuses and it may be good for a few months but I may last a few years. It's not as scary as I was told. I wouldn't be scared to do it again. Takes about 45 mins or less to take out and Same to put back together. Took about 30 mins to pull the hv pack apart and put back together. The big delay was waiting a week to get the modules
     
    #10 tintmanpa, Sep 28, 2017
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  11. bisco

    bisco cookie crumbler

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    that sounds right, all the best!(y)
     
    #11 bisco, Sep 28, 2017
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