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Hybrid battery Temp confliction

Discussion in 'Gen 2 Prius Technical Discussion' started by 80sguy, Oct 20, 2023.

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  1. 80sguy

    80sguy Junior Member

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    Hi everyone. Still a new guy here. I've done some searching through threads and found some very conflicting answers to proper traction battery temperature. Our latest gen 2 while checking the battery temp via Dr Prius, I was cruising on the highway at 65 miles an hour on a 60° day and all three temperatures were tickling 100 and and occasionally went up to 105.
    Sounded high so I checked one of my other Priuses, and under the same conditions I'm running at 75 to 80°
    So I did some research and decided to clean the hybrid battery fan. It wasn't terrible but it was far from clean. Curiously on the way to my shop to do this on that day, it was running 65-75 or so degrees according to Dr P. Same conditions but huge drop in temp. Now
    AFTER cleaning and replacing the fan on the way home on that 50° night it started to surge up to 110. So I opened all the windows, froze my butt but drove it home and it stayed around 85-90 on the trip back. When stopped I could hear the hybrid fan running so I doubt that is the problem?
    I guess my questions are: what is the max temperature your hybrid battery should run at?
    I live in central New York and the temperature changes pretty dramatically over the year but what should I expect for temp on let's say a 75 degree day?
    And last what could possibly explain why the battery was running hot, then it ran cool, then I changed the fan and it ran even hotter?
    Thanks for any help/ advice.
     
    #1 80sguy, Oct 20, 2023
  2. PriusCamper

    PriusCamper Senior Member

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    There's three different temp numbers... Are they all the same? In general your pack is within range of normal temperature. But when the hot weather returns, it's possible you have a bad cell that's running hot and will likely show up in the data and testing as normal for now.

    If you want to find the cell that's running hot, you'll need to pull the metal cover and point a thermal camera on it. It won't take more than a second to find it with a decent thermal camera. If you don't have one but have a friend who does home inspections, they have one.
     
    #2 PriusCamper, Oct 20, 2023
    Last edited: Oct 20, 2023
  3. 80sguy

    80sguy Junior Member

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    Hey Prius camper thanks for your response. All three temps were close to the same with the middle one of course being the highest. Tonight coming back from work 57° out my Prius ran from 85 to 95 once I got on the Thruway.
    Do you know what temperature range is ideal for the battery? Or harmful for the battery?
    The reason I originally worried is because I read on one of these threads not to let the battery get above 110°. And of course yes there's three different battery temps but it's easier just to list one here in the post
     
    #3 80sguy, Oct 20, 2023
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  4. ttou68

    ttou68 Active Member

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    If I remember correctly, optimal temperature range should be between 75° ~ 78°, and no higher then 110°

    lithium ion battery should not higher than 113°

    Posted via the PriusChat mobile app.
     
    #3 ttou68, Oct 20, 2023
  5. PriusCamper

    PriusCamper Senior Member

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    Lol... So what happened to every last hybrid and electric car in Arizona this Summer when fossil fool driven climate change sustained temperatures of 110 degrees F for 54 days in a row? The answer is nothing happened because your temp limits are not high enough. Phoenix hit 110 degrees on 54 days in 2023, setting another heat record | PBS NewsHour
     
    #4 PriusCamper, Oct 20, 2023
  6. dolj

    dolj Senior Member

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    Isn't the OAT moot as you will have the A/C on to keep the cabin cool enough to be comfortable? The battery cooling is drawn from the cabin, after all.

    I imagine most people set the cabin temperature to somewhere around 72 - 75ºF. You might have it set higher on a hotter day. What is comfortable for humans will be comfortable for the battery. If you're worried about the battery temps you could always make it cooler in the cabin.
     
    #5 dolj, Oct 21, 2023
  7. mr_guy_mann

    mr_guy_mann Senior Member

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    If the fan and ducting are clean and functional then ignore it and move on with life.

    The engineers did a pretty good job designing thermal management on the Prius HV pack. My 06 went 14 years and 160k before it needed battery work.

    Would the pack last longer if it was cooler? Sure, but you run into "problems" of noisy fan complaints or fan motors wearing out. Most people would not like the compromises (more $$ and noise) needed to improve average battery life by "X" percent.

    Posted via the PriusChat mobile app.
     
    #6 mr_guy_mann, Oct 21, 2023
  8. 80sguy

    80sguy Junior Member

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    Thanks all
    You can see why I'm concerned about the temp...no general consensus.
    Here is my other worry. When I took the fan out to clean I hit it different angles which made the fence in both directions. Could it be possible that going backwards damaged the motor such that it runs still ( I hear it run) but it's spinning as fast as it should.
     
    #7 80sguy, Oct 21, 2023
  9. mr_guy_mann

    mr_guy_mann Senior Member

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    <shrug>

    If the battery temperature gets "too" high, the ecu will set a code. You normally can't hurt the fan motor by spinning it. The ecu monitors the voltage it uses to control the fan - if it's out of range (ie the motor or wiring goes open circuit) it will set a code (not as good as a direct RPM sensor, but "good enough").

    Under most conditions that I have seen in 50k of Gen2 ownership in NJ, I do not hear the fan operate 99% of the time. That means the fan is at speed 2 or less - when I bother to check battery temps, it goes to speed 3 (audible) somewhere in the 120's degrees range. That's moderately warm-hot water temps.

    Do your own research, make your own conclusions and decisions. Some people fuss with temps and use apps to run the fan high all the time. Others leave it alone unless the ecu flags a problem. For me, any possible gains are not worth the hassle. If the car temperature is comfortable for you, then the battery temperature should be fine.

    Posted via the PriusChat mobile app.
     
    #8 mr_guy_mann, Oct 22, 2023
    Last edited: Oct 22, 2023
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  10. 80sguy

    80sguy Junior Member

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    Thanks Mr guy
    I wasn't aware of any apps that would increase that fan speed. I didn't think it had any kind of Rio stat or anything to very voltage but either way I'm not going to worry about it. As long as I've got no codes like you said I'm probably okay. It just kind of shocked me that got so much higher after I cleaned the fan then it was before I cleaned the fan. It makes sense that the fan wouldn't be hurt by spinning at the wrong direction. I don't know what mechanism is behind it but box window fans can spin either way if pushed by hand and I don't hear them complaining afterwards lol. I'll just keep an eye on it. Appreciate the feedback. Sorry I'm just getting back into this I was in the hospital
     
    #9 80sguy, Oct 25, 2023
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