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HV Battery temperature

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by TonyR, Sep 15, 2024 at 7:23 PM.

  1. TonyR

    TonyR Junior Member

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    My 2004 200k mile Prius has started to throw up warning lights - the warning triangle, the circle with the ! and VSC - on the dash after driving for a while. If I clear them after leaving the car overnight it will be fine for a while and then come back. It was starting to get down to a few miles before they cam on. I took the fan out and cleaned it and just did two 40 min journeys thinking it had solved it but they cam back at the end of the second journey.

    The battery looks OK - it goes to full charge, and the battery cells are all even voltages and resistances. So it doesn’t look like a cell failure. When the warning lights came on I read the data and its on Fan Mode 2 with a battery temperature of 38C/100F. Does this sound about right for the battery temperature warning to trip?

    The poblem is clearly a temperature one as if you leave the car to cool overnight it takes a while before the warning comes up. Would appreciate any thoughts on what is going on.
     
    #1 TonyR, Sep 15, 2024 at 7:23 PM
  2. Brian1954

    Brian1954 Active Member

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    Why are you clearing the trouble codes without reading them. The trouble codes will tell you the problem that the car is seeing.
     
    #2 Brian1954, Sep 15, 2024 at 7:30 PM
  3. Tombukt2

    Tombukt2 Senior Member

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    Since you can figure out how to clear them you should be able to figure out how to read them with a capable scan tool then that light bulb might go off and burn brightly how do you know your battery is getting hot who told you that? Or what determine that? The energy monitor on your multifunction display when you're driving the car how fast does it change from blue to green and back to red magenta and then back to blue and then back to green and maybe back to blue and not even see the magenta because you're driving how fast does that display changing? Do you hear the fan in the right rear quarter panel running like crazy You stop at a stoplight you hear a fan behind you running on near full tilt? No then probably not an overheating problem Why would you think it was a battery overheating problem Is it warmer in the car I mean just got to be a reason we're talking about temperatures because it's hot outside You don't drive around when it's 100° out with your air conditioning on and the windows rolled up that's the air the battery fan is sucking across the battery and then blowing it out the right rear quarter.
     
    #3 Tombukt2, Sep 15, 2024 at 8:04 PM
  4. mr_guy_mann

    mr_guy_mann Senior Member

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    100°F is barely "luke-warm". I personally can't hear the fan operate until it reaches speed 3 at about 125°F. You need to be able to check the Hybrid Control and High Voltage Battery ecu's for codes (either when the warning lights come on, or before clearing codes.)

    What scantool device-app are you using?

    Posted via the PriusChat mobile app.
     
    #4 mr_guy_mann, Sep 16, 2024 at 12:54 PM
    Brian1954 likes this.
  5. TMR-JWAP

    TMR-JWAP Senior Member

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    Not reading codes and jumping to a temperature problem is a bit of a leap, but don't forget there are two ends of a car............one end has an HV battery and the other has an inverter.......

    As for this.....

    When the warning lights came on I read the data and its on Fan Mode 2 with a battery temperature of 38C/100F. Does this sound about right for the battery temperature warning to trip?

    No, no it doesn't....that actually sounds nice and cool.
     
    #5 TMR-JWAP, Sep 16, 2024 at 1:56 PM
  6. TonyR

    TonyR Junior Member

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    I’m clearing the codes because they are the same every time and I’d rather drive around without a warning so I can pay attention when one pops up. But the codes are POA85 and P3000.
     
    #6 TonyR, Sep 16, 2024 at 2:38 PM
  7. TonyR

    TonyR Junior Member

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    I’m hypothesising a temperature problem somewhere as it takes a while of driving before the warnings come on and once they are on it takes a long while off before you can clear them. I can’t think of many things that would have those time characteristics.. Leave it overnight (when it would cool back down) and just the warning triangle is lit and the codes will clear. Everything drives normally whether they are on or off. Battery charges and discharges, electric motors kick in and battery (amazingly for an original battery on a 200k 20 year old car still goes to full or next to full bars.
     
    #7 TonyR, Sep 16, 2024 at 2:47 PM
  8. TonyR

    TonyR Junior Member

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    upload_2024-9-16_20-9-29.jpeg

    Its a Gen 2 and doesn’t have the multifunction coloured display you mentioned. No, you can’t hear the fan. And when the warning comes on the fan isn’t running. It was a bit dirty so I gave it a good clean anyway. And no, its not hot around here. I’m guessing temperature because of the time it takes to come on when you are driving, and it comes on faster if you drive hard, and that it takes a long time switched off before the codes will clear. Can’t think of many things with those characteristics other than warming up and cooling down. BICBW
     
    #8 TonyR, Sep 16, 2024 at 3:13 PM
  9. Brian1954

    Brian1954 Active Member

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    What scan tool/app are you using to read the trouble codes?

    My guess is that the scan tool that you are using is not capable of reading all the trouble codes, and there are other codes that have been triggered that you are not able to read with your scan tool.

    See post #4 about the ECUs that need to be read by your scan tool.
     
    #9 Brian1954, Sep 16, 2024 at 5:08 PM
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