Red Triangle "Problem" - Low 12V Battery?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by maleko, Aug 30, 2020.

  1. maleko

    maleko Member

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    Hey everyone, so a couple of months ago our 2008 (100+k mi) Prius gave my wife the Red Triangle "Problem" while she was out and about with the kids running errands. It happened while she was at my office visiting me, so we switched cars and I let her take mine home while I gave our Prius a rest as I finished out the last half of my work day. I pretty much figured it was the inverter coolant pump since I had already previously replaced the coolant diverter valve that likes to get stuck and throw its own code. I got it home after work that day and pulled the codes with Techstream and it was the inverter pump as I thought so we replaced it and it was back to being a reliable family Prius again.

    (I should also note, I recently replaced its HV battery as well with a good quality used pack from a reputable member here so I am confident no further issues should come from that.)

    Fast forward some weeks/a few months and now I am working from home and our Prius gets even less driving time each week than it used to. One day, the whole family piled into the car and pretty much spent the entire day in the Prius running errands, traveling on the highway, through the city, idling in parking lots, with the A/C blasting on max cold the entire time in the dead of summer, etc. As we were nearing home we got the Red Triangle "Problem" again and our A/C stopped cooling. This time I had no clue what it could have been other than a possible air pocket in our cooling system or a weak 12V AUX battery. (We bought the Prius in California in late 2014 and have never changed the 12V battery out yet.)

    A couple of weeks went by with it sitting in the driveway as I put off pulling codes due to needing to re-install Techstream again, and by the time I did go to pull codes last week, I realized the 12V battery was nearly dead after unlocking the car and sitting in it for a few minutes on ACC mode, not running. During that time it threw the "parking mechanism/pawl" warning which I am confident was purely from the low 12V battery. So naturally, I removed the 12V battery, freshened up all the connections and put it on a 2A smart trickle charger for about a day and a half until my charger gave me the "fully charged" indication at which point I put it back in the Prius and cleared all codes. I have driven it a few miles since and it did not immediately throw any new / major codes (besides its lifelong codes that I know it carries, but that don't illuminate the CEL).

    Could a weak / failing 12V battery cause the Red Triangle "Problem" issue to occur randomly / intermittently? If so, does the Prius just always elliminate the air conditioning whenever the Red Triangle gets thrown? Should I be concerned my inverter, A/C compressor, or transmission could be on their way out?

    EDIT:
    Also, after installing the re-charged 12V battery, I was getting 11.9V (via Techstream) while in ACC mode with nothing on, and 11.3V with A/C and headlights on. Also, while sitting in the driveway with the A/C on high MAX COLD as I was pulling codes with our Prius idling, I noticed a metallic tapping sound, but not from our engine. I turned the A/C off and it stopped. So that has me wondering if any of this could be related to a failing air conditioner compressor... Except for the fact that our Prius's A/C is ice cold and operating within tolerances as far as its cooling ability goes.
     
    #1 maleko, Aug 30, 2020
    Last edited: Aug 30, 2020
  2. ChapmanF

    ChapmanF Senior Member

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    There are on the order of a couple hundred conditions that can light up that triangle, and some of them will shed the air conditioning and some of them won't, and some of them indicate scary big deals and some of them don't.

    If you create an opening "could my battery have made this occur randomly" around here, it's almost guaranteed you'll find somebody to tell you oh yeah, totally, sure thing. But there are other possibilities equally or more likely, including that some of the codes you haven't read were telling you "hey, d'you know your battery's low?", or that some of them were legitimately telling you something else.

    As long as none come back, don't worry about it. If any do come back, instead of guessing and worrying, I'd suggest finding out what they are.
     
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  3. edthefox5

    edthefox5 Senior Member

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    It has all the signs of a bad hybrid battery. Unless its a brand new battery from the dealer it is highly suspect.and not a new battery it has been rebuilt with the same vintage battery blocks it already has they just have not failed yet. Nothing high quality about it its simply a temporary stop gap with a very short life. And a money maker for whoever did it.

    First thing that the car shuts off when the hybrid battery struggles is the ac.

    You do not give us any hybrid battery metrics as far as how does it's charging and discharging behave?
    How do the blue bars behave are they moving around up and down alot?. Do those blue bars tank to purple bars pretty quickly like at a light or at a drive through? And if it gets to a purple bar or two how fast does it recover to 1-2 blue bars.
    Does it ever get to no bars at all alot thats RTOD time for sure.

    Lastly the quickest way to kill your rebuilt battery is to not drive the car. That will kill both the hybrid battery and the 12 volt battery as you have found out.

    The car must be driven everyday. On the highway not around town. At least 15 miles to keep both charged. Sorry but that's the hard truth of owning a 13 year old Prius..

    So many posts of bad hybrid battery's on G2's now. The no driving kills them. I just installed a brand new pack in my bought new 07.
     
  4. maleko

    maleko Member

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    The HV pack I had replaced recently is a rebuilt pack from a wrecked 2015 that had 30k mi on it. New wiring harness, cells charged and tested prior to rebuilding, etc. It's really pretty low on my list of suspects.
     
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  5. dolj

    dolj Senior Member

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    I don't do either and my HV battery is just fine. My 12 V battery, though, I keep on a charger when I know it will not be driven 3 days or more.

    The sky has not come crashing down yet.

    Mind you, we don't have extreme heat or high humidity around these parts either, so that is nice.
    No, not likely the compressor. More likely one of the air damper/blend motors getting overactive due to an electrically noisy position sensor.
     
    #5 dolj, Aug 31, 2020
    Last edited: Aug 31, 2020
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  6. maleko

    maleko Member

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    I did just pick up a NOCO Genius 5 charger since my "old-school" (transformer-style) Schumacher digital with microprocessor charger stopped working right after getting my Prius' 12V fully charged. (I never did like/fully trust that charger for some reason, lol) I trust the NOCO way more and it even has a "repair" mode to help de-sulfate older batteries. I figured it can't hurt to try while I decide on my replacement 12V battery setup.
     
  7. bisco

    bisco cookie crumbler

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    a rebuilt used battery pack is a new one around here. 30k on the 2015? 30k on the pack after it was rebuilt and you bought it, or you have put 30k on it?
     
  8. maleko

    maleko Member

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    The 2015 wrecked Prius the HV pack came out of only had 30k miles on it. We bought it and installed it into our 2008 Prius in August 2019 about a year ago. Our Prius is not our primary commuter anymore since I got a 2005 Corolla, and our Prius gets driven even less since March with the pandemic and everything. I doubt we have even put 5 to 10k miles on the HV pack in the year we have had it in our Prius.
     
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  9. bisco

    bisco cookie crumbler

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    thanks, that makes more sense
     
  10. SCdave

    SCdave Junior Member

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    Ordered a Noco Genius 5 and arriving today.

    Have been searching online for Prius Gen3 specific charging guidelines but just find generic 12v info.

    If you/qnyone has any suggestions and/or YouTube or other references, please let me know.

    I'll read the Noco Genius5 manual but questions I have
    - pull 12V AGM and charge out of car in garage,
    - leave in Car and connect charging leads on engine bay "Prius Jumper" points re Prius Owners manual.

    Thanks

    Posted via the PriusChat mobile app.
     
  11. SCdave

    SCdave Junior Member

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    Let my thumbs work a bit harder and found answers to my above questions on Priuschat.

    I'll use the Prius Gen3 "Jump Start" connection in Engine Bay re Owners Manual.

    With 2020, my 2015 Prius has not been driven so much. My 5 yr old original 12V battery has been at 12.1v SOC. So want to charge it with the NOCO Genius5 and put it thru a desulfanation/reconditioning cycle.

    Hopefully get 12.8+ v after charging and a few more years of life.



    Posted via the PriusChat mobile app.
     
  12. sam spade 2

    sam spade 2 Senior Member

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    Usually a complete waste of time, especially with an AGM battery.
     
  13. dolj

    dolj Senior Member

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    FWIW, I find connecting the pigtail directly to the battery in the back to be more convenient. But each to their own.

    And I agree with Sam, just charge it up and forget about the desulfation/reconditioning cycle.
     
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