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HV Battery down to one bar, fan on. Disconnect battery and fan off, 4 bars and dash lights. Huh?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Priusyipee, Sep 7, 2023.

  1. Priusyipee

    Priusyipee Active Member

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    Driving home on August 25th. Battery is no longer charging and SOC drops to one bar (purple) on the MFD. The dash lights up, warning triangle as well as hybrid warning (car with exclamation point on MFD) and the rear battery fan is on full blast. For the entire 44 mile ride home, the battery stays at one bar even though it appears that it is charging.

    Came home let the car sit overnight and disconnected the 12V. When the car is restarted, the fan stays off, the dash lights stay on but the SOC was up to 4 (blue) bars on the MFD. There is turbulance in the inverter coolant so that rules out a burned out pump.

    It's a 2008 with 305,091 miles. I was hoping to get another 3 years out of it as early in the spring, I changed out the struts, hub / bearings, muffler, and brakes. Why would the SOC go up after it was turned off with only one bar?

    Unfortunately, I did not have the codes pulled. Will be taking it to Toyota on 9-21 to get the battery replaced. 2600.00 out the door. Is there a possibility that it could something else?
     
    #1 Priusyipee, Sep 7, 2023
    Last edited: Sep 7, 2023
  2. Tombukt2

    Tombukt2 Senior Member

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    Not really likely probably it is just the battery going south You're lucky it hasn't fallen on its face flat yet like mine did a couple of mine have done $2,600 out the door that's great just run with it that's the way to go in your case I'm sure and get some kind of warranty too and all that perfect. The car seems to be charging fine other than the battery not managing the charge very well as in being able to keep it other than that it wouldn't matter I mean having to swap out a transmission for MG1 or two and or an inverter at some point That's really not big stuff in these cars. And parts are becoming more and more plentiful by the hour these things are coming off the road and droves. I've broken down I'm fixing to go buy another one beautiful car in perfect condition sitting at a tow lot ridiculous
     
    #2 Tombukt2, Sep 7, 2023
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  3. dolj

    dolj Senior Member

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    Because you disconnected the 12V. The ECM resets to a factory default of 60% SoC. It will recalibrate given enough time.
     
    #3 dolj, Sep 7, 2023
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  4. Tombukt2

    Tombukt2 Senior Member

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    It'll also just surface charge sitting I go up to cars all the time that have been sitting like 90 days nobody's done nothing or anything. I walk up to the car slot the remote push to start button engine starts right up I put it in reverse or drive back it up a couple hundred feet pull it forward leave it in drive watch it charge up turn it off in 5 minutes or whenever the engine shuts off and just turn it off.
     
    #4 Tombukt2, Sep 7, 2023
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  5. mr_guy_mann

    mr_guy_mann Senior Member

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    When you disconnect the 12V battery, you give the HV battery ecu "amnesia" - it forgets the faults that it detected when it set codes and turned on the warning lights. (you effectively clear all the codes).

    As mentioned, 60% SOC is the default for the ecu until it can resample enough voltage data to make a more accurate reading.

    While it is very likely that you have a failing HV battery pack with P3000 and P0A80 codes, you would have to have a capable scantool to check the hybrid control and HV battery ecu's to confirm.

    Here is a thread that reviews a number of scantool apps and devices. Some are more basic, and others are more capable.

    https://priuschat.com/index.php?posts/3290690

    Posted via the PriusChat mobile app.
     
    #5 mr_guy_mann, Sep 7, 2023
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  6. Priusyipee

    Priusyipee Active Member

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    Going to mess around a bit with it this week if I have time just to get a better idea of what's going on although I sure it's the HV battery. Since 2017 the SOC has consistently fluctuated between all green and purple. I was sure 6 years ago that the battery was on borrowed time but it managed to pull through an additional 6 years of 100 mile commutes 5 - 6 days a week!
     
    #6 Priusyipee, Sep 11, 2023
  7. Tombukt2

    Tombukt2 Senior Member

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    Yes as long as you keep it on the road those hundred mile commutes everyday can make your battery last a little longer I imagine there was a few module
    swapping steps in they're .
     
    #7 Tombukt2, Sep 11, 2023
  8. Priusyipee

    Priusyipee Active Member

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    Nope. The battery is original. Never touched.
     
    #8 Priusyipee, Sep 11, 2023
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