HV Battery Cell Replacement

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by GEORGE E, Apr 7, 2019.

  1. GEORGE E

    GEORGE E New Member

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    2007 Prius purchased new 12 yeas ago. I Replaced a bad cell about a year ago. All fine until I just had front wheel bearing and front brakes replaced. Went to pick it up and 12 volt battery was dead. They charged it and all OK for a few days. Now I'm getting code P0A80. Checked the cells with Torque Pro(motor off) and all banks read ~16.3 volts except one that reads 14.9. Could this one bank cause codeP0A80 at 14.9 volts? The repair shop said that the cause of the dead 12v battery could have been caused by another prius key fob being to close to my car while they worked on it. Should I hold them accountable, or should I replace the bad cell(or cells) and see if it solves the problem??
     
  2. bisco

    bisco cookie crumbler

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    how old was the 12v?

    i would replace the bad module
     
  3. TMR-JWAP

    TMR-JWAP Senior Member

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    My opinion (and we all know what that is worth!!) is there's nothing to hold them accountable for, other than draining and recharging the 12v battery. The work they did should, in no way, cause a module in the HV battery to fail. This one falls under coincidence. One of the modules has a failed internal cell. After the first failure a year ago, you should just go ahead and expect an annual (or more frequent) rebuild cycle, as the other modules are still original 2007s. If it goes more than a year that's great, if it goes 2-3 months before the next failure, it's not unexpected or unheard of. Unless you have the equipment to get an accurate assessment of each individual module, it's practically impossible for someone to optimize the battery.
     
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  4. GEORGE E

    GEORGE E New Member

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    The 12v battery is only 6 months old and is holding a charge just fine. With all HV battery modules all reading about 16.3 volts except for one bank that reads about 1.2 volts lower, I was wondering if at around a volt low if this one bank could cause the faults. I don't have a problem with replacing a bad cell and this will be my next move. When I took the car back after the first fault to the people who replaced the brakes and bearing they said they found 2 wires under the car that were chafed bare and repaired them. They did not confess to chafing the wires during their repairs. though. I wonder if the bare wires shorted out the system and damaged the HV computer along with draining the 12v battery, and now I'm getting bogus faults. Once I get this taken care of I'm going to sell it or trade in on a new Prius or Honda Insight. Looking at Insight because I think it's a much nicer looking car. Been waiting patiently for Toyota to come out with a better looking Prius but still not impressed..
     
  5. TMR-JWAP

    TMR-JWAP Senior Member

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    I recognize that 95% of Prius owners know very little about the electrical portion of the car. Probably 4% have a reasonable understanding of the electrical systems. <1% probably have enough electrical background to comfortably and confidently understand the systems. Probably less than 0.1% are FULLY capable of understanding all the systems. I would consider myself to be somewhere near the 1% group, having spent 30+ years in electrical and electronics fields.

    Think of the HV battery as a bedroom with 28 light bulbs. All 28 bulbs were installed 12 years ago. You're in the kitchen making dinner and turn on the oven light to look at that killer roast you're cooking. Everything is great, so you head to the bedroom to put on some PJs for the night. You turn on the bedroom lights and one is burned out. The chances of anything outside of the HV battery case causing a module to go bad would be about the same as if turning on the oven light caused the bedroom light to be burned out.

    And yes, that one failed cell that causes the 1.4v difference is exactly what the Gen 2 system is supposed to detect.
     
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