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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.
     
  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.
     
  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.
     
  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.
     
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  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.
     
  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.
     
  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.
     
  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
     
  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.
     
  10. TMR-JWAP

    TMR-JWAP Senior Member

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    ok, so you didn't recognize the hint about the inverter being on the other end of the car. Search P0A93, it's a relatively common failure of the inverter cooling water system, usually the electric pump located behind the driver headlight. Again, just guesswork without a code, but some guesses are more likely than others just due to experience. But, if you're accurate in that the car continues driving completely normal even after the alarms come in, maybe not a temperature issue, at least not the battery or inverter. Engine?.
     
  11. mr_guy_mann

    mr_guy_mann Senior Member

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    So, P3000 is set by the hybrid vehicle control ecu & basically means, "the HV battery ecu says it's got a problem" (in most cases).

    P0A85 is set in the HV battery ecu when it tries to control the battery fan, and the ecu doesn't see the correct (-) side voltage on the VM circuit. (for different "x"% signal to the fan controller should yield a different voltage on VM).

    The thing is, the code won't set at all until the ecu senses the pack temperature go up enough that it TRIES to turn the fan on. So yes, it is "temperature related".

    Have you confirmed that the fan actually runs (blows air)?

    My first "go to" test for this is to check the white connector behind the fan ducting in the right side of the cargo area - behind the interior body panel.

    Water leaks in from cracked body seam sealer around the tailgate. It then dribbles onto that connector and corrodes the terminals.

    3 of the wires are for the fan, the 4th is for the engine fuel pump. Most here just splice the wires to eliminate the connector (& also seal the leaky seams). gen2-batt%20fan%20conn.jpeg Screenshot_20240916-230230.jpeg

    Posted via the PriusChat mobile app.
     
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  12. TonyR

    TonyR Junior Member

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    Thanks for that. The fan doesn’t seem to be running is the latest. I had a look at the white connector earlier having read that can be a problem but it all looks pretty clean and tidy there with no evidence of water leaks or corrosion. Thsnks for the diagnostic printout though. Very helpful. I’m taking it in to Toyota this afternoon to see what they make of it.

    upload_2024-9-17_8-50-7.jpeg
     
  13. MAX2

    MAX2 Member

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    The fan does not work constantly. It turns on when needed.
    You can turn it on forcibly using the program on the phone and the connected adapter for OBDII
     
  14. Tombukt2

    Tombukt2 Senior Member

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    I think that's the wrong connector with that black tape on it doesn't look right The one you should be looking at is a little further up and it will not be taped and usually when you pull it apart the part that stays in the car is where you see most of the nonsense green corrosion a little bit of brown that sort of thing turn that plug around the part that stays in the car and look at the back of it might look similar sometimes the part that you unplug and comes out of the car or goes to the device and the ductwork or wherever it goes will have the green and brown corrosion on it too I've been lucky and been able to clean mine up plug them back up then waterproof the connection and it's done I haven't sealed any glued seams or anything like that I don't see any leaking to be honest with you I try with a garden hose running down over the seal on the hatch for an hour Don't see any water so I just wrapped the connector If I didn't have to jump it or do anything with it after cleaning with zip tape and seal it up permanently I have four of these cars they're all sealed up none of them are taking on water when I bought them many of them had water in the battery tray water in the spare tire well but nothing seriously standing just moisture once all the plugs are pushed out of the rear area now water will pass through it doesn't stay and visit so no terrarium effects or anything business.