My 3 year old toyota HV battery is running hot???

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by mcmars, Jun 28, 2022.

  1. mcmars

    mcmars Member

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    Hello folks, just in last 2 weeks I heard the fan come on a few times for the first time ever and am noticing the blue bars disappear quick and more purple bars than normal. I hooked up the dr prius app tonight and it told me that the 3 HV battery temps were getting pretty warm, with #2 being the worst at 122F. #1 was 112F and #3 was 108F. And that was just sitting in my driveway after it sat for an hour after running some errands. I used the app to set the fan start up temp at 86F so it comes on at full speed at start up now and will monitor the app tomorrow for a 100 mile drive I am doing to get back home.

    I bought this 2008 prius almost 3 years ago and replaced the HV battery with a brand new toyota battery I got a killer price on in late August/early Sept. I totally cleaned the fan then which was barely dirty and all the connections on the HV battery looks real clean when I installed the HV battery, and it has about 20,000 miles on it in less than 3 years. I just pulled the fan out again 2 days ago and it was just starting to show some fine dust I blew out with some contact cleaner, and changed the oil. I thought it was running better next day on the 8 mile mostly uphill ride to work as I had 3-4 blue bars when I parked at work, but the following morning in 60 degree weather with same drive it had 2 purple bars, weird?? I run the AC at 69 on low to max if hot when I get into the car after sitting in sun. I almost wonder if there is some intermittent thing happening as sometimes it seems normal and then it goes into the purple again, but I have no real idea how the prius works or thinks.

    But in any case, I feel something is not right and is making this fairly new battery get too hot and worried about a premature failure. I will call toyota dealer tomorrow and find out if the warranty might help me, but I did the install and not sure if they would honor it. I do suspect the problem is related to environmental conditions where I am, SW Utah with mega drought happening and summer temps up to 110 or more at the high extreme and lows to zero or less, no garage, some shade. But then again, I see gen 2 prius vehicles all the time here?? Maybe I got an old battery that sat in warehouse? Maybe just bad luck of the draw? But I bet there is a reason and hoping to get some ideas to explore to figure this out. Thanks for your help!
     

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  2. Tombukt2

    Tombukt2 Senior Member

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    New battery as in new battery from the Toyota dealer or real Toyota battery without the computer tray attached to the front of it and all that or a refurbed new like battery?
     
  3. mcmars

    mcmars Member

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    I bought a brand new HV battery OEM toyota battery. Paid the core charge, swapped out the battery using the great video from Boulder Hybrids and then returned my old core to get the core charge back. I went this route to avoid the issues with buying a refurb battery that only last a few years, but now I am having issues as if I had bought a refurb. I am calling dealer in Durango where I bought it right now to see what they think and find out about warranty for it. Seems it had a 3 years warranty???
     
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  4. Tombukt2

    Tombukt2 Senior Member

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    Well that's right I think that's what you get on these things is like a 3-year warranty etc etc but at least you know you have all new sales while they're 3 years old now so I don't know what you've got a few bad cells or what's going on maybe the HV computer is starting to fail that was transferred over from your other battery generally stays with the car so that I guess there's a bunch of things to check I don't know if you've got codes or all of that but I just did the same thing I'm almost 9 months in or something haven't had any kind of a problem '09 Gen 2 we beat the hell out of this car to work vehicle looks like hell inside reasonable outside that kind of thing it's the ugliest vehicle in the world it's the gold with the tan cloth interior that stains and is just ugly immediately No cure for that
     
  5. mcmars

    mcmars Member

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    I called toyota and they say my warranty is 12K/1 year, so that does no good. I can see them for a $143/hour service rate to run a diagnostic on the battery and vehicle to try and troubleshoot further, who knows where that might go, probably way north of my wallet.

    I called the great shop Boulder Hybrids that made the video I used to do the swap and talked with them. They recommended I check the cooling tubes to see if maybe they came undone which I had wondered about and might try and fit that in after I take a short vacation on a week long river trip. I asked how often the fans themselves fail as I noticed mine was not turning freely like you might expect a nice ball bearing fan to spin, maybe these are just a cheap bushing with some friction?? She said they do fail and eventually you will get the code, but maybe mine is not to that point. Maybe look for an ebay fan was her suggestion if I want to swap it out.

    I have a music festival planned near Boulder in August and maybe if I can't get this figured out, I can have them help me after the show? I said I could run it easy for a while or use my old subaru for a while if it keeps running warm to not damage battery and she said she would do the opposite and run it hard to get the computer to throw a code. She said the normal range of temps go up to about 110F and above that is considered hot.

    I don't think there is any hybrid shops anywhere near me, kind of a desert of hybrid help out here. 365 miles to Boulder. Or maybe some help in Albuquerque 215 miles away. But hoping I can get some help here and figure out why I am running hot on this new OEM HV battery?
     
  6. mcmars

    mcmars Member

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    Haha, mine came real clean when I bought it at 143K miles with a custom leather interior somebody paid some big money for in Vail CO. Still looking pretty nice, but I am not OCD at keeping it pristine like the prior owner, I like the looks personally, but beauty is in eye of beholder.
     
  7. bisco

    bisco cookie crumbler

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    110f is hard on batteries, and sw usa tends to have shorter lived hybrid batteries anecdotally.

    maybe open everything up again and make sure it's still clean inside the battery, fan and intake grille.

    keep the a/c on high.

    nothing you have presented suggests a failing battery, but some go so far as to keep the cooling fan on high all the time, and even creating better flow through the center battery modules.

    for peace of mind, you might want to run a health check with dr. prius or tech stream
     
  8. dolj

    dolj Senior Member

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    Did you have to tighten any of the terminal nuts or are the busbars fitted at the factory? If you did, did you use a torque wrench to tighten them to 48 in-lbs (i. e. 4 ft-lbs)? Regardless, it could be worthwhile to go over each terminal nut with a torque wrench to check them. Check all the other electrical connections too to ensure they are tight.
     
  9. SFO

    SFO Senior Member

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    Start by always cooling down HV battery after parking the car, it can take many minutes with the AC on and the fan set on high (6). Once the battery is under outside ambient, then turn the vehicle off. Always park in the shade with the windows down, or the direct sun if you must. Consider installing ceramic window tint to slow interior heat soak, which will then soak into your hv battery.

    I've only heard of one (possibly two) new oem hv battery replacements failing in 3 years, one was in Florida.

    Did you install the foam air dams before placing the hv battery cover back on?
    You can check it if you have a smaller pair of circlip pliers, or just remove the sticker and add a drop or two of light weight machine oil.
    After a dr prius test, do a single session with a grid charger/discharger and see if the the perceived SOC (state of charge) varies, then retest.
     
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  10. mcmars

    mcmars Member

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    Thanks everyone for the tips! I think I might check inside the battery case to see if the foam dams are in right place and that the vent tubes are all in good condition, but it might have to wait till I get some time. I believe I used my fancy stainless precision 1/4" torque wrench. I will run that 15 minute dr pruis health test. I did tint the windows to help with the heat and will start using a windshield sun shade, but shade out here is a limited resource and leaving windows down for even a few hours can be a disaster when a sand storm fill the car with fine sand. But I can crack them a bit.

    I think just bumping the fan start up temp back to 85 made a difference on the 200 mile drive I had today, but to be honest, it was cooler including driving through a pounding thunderstorm while going over a mountain pass to Durango. I went to Durango to go to Discount Tire as when I checked my tire pressure 2 days ago, I notice the Nokian tires I bought 22K miles ago, just under 3 years old, were all dry rotted on the sidewalls and I knew I needed to buy new tires to be safe. I guess that is also an indicator of just how hot the last few years have been to destroy those tires so fast? They gave me a great pro-rated deal on a set of michelins and on the way back to Moab from Durango the readout claims I got 54.6 MPG for the 166 miles I drove with new tires at 36 PSI! I normally average 48.2, but I had a bit of a tailwind and there is a 3K elevation difference between the 2 towns. But I could tell the new tires coasted way faster and longer than the old ones.

    So today with the fan coming on sooner, cloudy cooler temps of 75 to 88F and new tires, the middle sensor was about 20 degrees cooler, around 100, with the other 1 outside sensors reading 7 and 9 degrees less. I did figure out I need to put the prius in park when I get to a destination and the battery is warm to cool it down before I shut it off. I also could see how the long mountain downgrades really do add a few degrees of heat due to charging, I went from 77% to 30% today going up and down long mountain grades. But coasting downhill to Moab (4000ft) and 90 degrees, the middle sensor temp got to 112F.

    So I wonder if my issue is really just environmental and maybe the battery is starting to react more than before as it gets stressed and is aging. But I do feel better knowing I can monitor it with the app and take a few precautions to help keep more air flowing. It seems by now there might be an aftermarket improved hiflow fan to install that would provide more air, Maybe a hose with a booster fan that attaches to the passenger AC vent and connects direct to the fan intake to provide cold air into the vent, or a fatter tube to feed the middle area of the battery to get more airflow where you need it the most or some other hacks to help with the issue of keeping the battery happy and cool under hot conditions?
     
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  11. TMR-JWAP

    TMR-JWAP Senior Member

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    They recommended I check the cooling tubes to see if maybe they came undone

    Thanks everyone for the tips! I think I might check inside the battery case to see if the foam dams are in right place and that the vent tubes are all in good condition,

    They are not referring to the vent tubes installed on the top of the battery, they're referring to the ventilation ductwork between the cooling fan and the battery itself. The rubber tubes on top of the battery are not part of the cooling circuit.

    If you remove the cover from the HV battery, immediately take a photo or two when the top has been removed, prior to touching anything else. Post those photos. Several here have enough experience to look at those photos and tell if you have an airflow problem.
     
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  12. mcmars

    mcmars Member

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    OK, I am tied up for a few weeks with a vacation and some work, but will get a peek inside the battery in a few weeks to inspect things
     
  13. fotomoto

    fotomoto Senior Member

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    So around 6.5k miles/yr average which either means a lot of short trips or long periods of non-use in the heat/sun of the desert SW or both; none of which is good for battery health.

    I would look into battery conditioning with a grid charger.
     
  14. SFO

    SFO Senior Member

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    Read some of the posts by @Grit - doubtful is anyone has a better setup at this time, though you could be on to something.
    Which michelin tires were those, or a link?
     
  15. mcmars

    mcmars Member

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    Mostly trips back forth between 2 homes 100 miles apart and some shorter trips, but I have an old suburban I use a bit for hauling and an old 96 subaru legacy that will never die and gets some winter use. I did let it sit for 2 months in winter of 20-21 for Dec and Jan while I was busy feeding wood in a stove in my colorado home, but I think it is the extreme hot summers we have had last couple of years that might have stressed it if there is a problem. We are about to go into the really hot part of the season with 100+ temps, I think I will move my suburban into the sun and use the shady mulberry tree as a park spot for my prius.
     
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  16. mcmars

    mcmars Member

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    I bought the Defender T&H in standard size for gen2 prius. Hoping it will give a bit of traction for winter use with occasional light snow and get me up a gravel driveway on slight hill. I liked the way they felt yesterday, big improvement over the Nokian that failed with the sideway dry rot from the heat.
     
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