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Easiest way to test hybrid battery cells?

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

  1. valegians

    valegians New Member

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    Hello,

    I was driving my 2004 Prius on a long road trip when the large red warning triangle, the hybrid system warning, and several other warning lights came on. I stopped and after turning the car off and on the only lights remaining are the large red triangle and the orange/red hybrid system warning.

    I was in the middle of a mountain in the middle of nowhere (100 miles from home) and the engine was still running so I tried driving home and the car worked fine. Only thing I noticed is that the battery would never charge the last bar (on the display). Other than that the car ran fine and the mpg was good.

    I got home and this morning I ran the Vehicle Signal Check diagnostic and here are the results:
    - Battery (with car in standby): above 12v
    - Battery (with engine on): 14.3v
    - Battery (while driving slowly for 2 minutes): 14v

    I also unplugged the hybrid battery (by removing the safety plug for 15mins), but the red triangle and hybrid system warnings are still present.

    (Sidenote: during the road trip the fan in the rear passenger seat was going pretty hard, outside temp was around 90F).

    I am planning on ordering the Mini-VCI cable to read any codes but that might take a couple days.
    I currently have my hands on a multi-meter and I was wondering if there was an "easy" way to test parts of the hybrid battery without having to take it completely out.

    This YT video the guy does a "no load" test, however it's unclear if the battery is in the car or not.


    Any help would be appreaciated, thank you.
     
  2. SFO

    SFO Senior Member

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    Welcome to PriusChat!!

    How many miles on the vehicle, and do you know if the HV battery is the original?

    It sounds like the HV battery is failing. Which part of CA are you near, as the borders cover a fairly large area.
     
  3. bisco

    bisco cookie crumbler

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    have your 12v load tested, and wait for the tech stream to test the hybrid battery. no easy quick way until you have the tools.
     
  4. valegians

    valegians New Member

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    Vehicle is at 169k miles. I bought it used summer of 2018 and the dealership said they recently replaced the battery (my guess would be a refurbished one, if they even did replace it).

    I live near Santa Cruz.

    For brevity I didn't mention in the post that I am actually at a friend's house and still 180 miles from actual home. Do you think I can make it back?
     
  5. SFO

    SFO Senior Member

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    Going over the 17 would be hard on that HV battery, you might go around if you're near the coast.

    What are the other options, would you leave the vehicle at the friends house?

    Are you thinking of a DIY fix, or might you get another HV battery assembly?
     
    Raytheeagle likes this.
  6. valegians

    valegians New Member

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    First, I just wanted to say thanks a lot for the help!

    For driving, I can stick to 101 so hopefully that's not too bad.

    I'd like to do a DIY if possible which is why I can't really leave the car. Last time I took it to Toyota I was out of pocket for almost 5k. I guess the alternative would be getting a Uhaul w/ trailer.

    I do my own oil changes, bulbs and other basic stuff but I'm not sure if the battery is too complex.

    Another issue here is I am likely to have to sell the car in a few months because of relocation, so DIY replacement of a couple of cells might be the best option.
     
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  7. SFO

    SFO Senior Member

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    If you have tools and some time, you might want to clean the HV battery fan before driving again, think of it as a pre-run for module swapping.
     
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  8. valegians

    valegians New Member

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    So here's an update.

    I drove the car back home (~180 miles) on the freeway. No issues besides the red triangle and the hybrid warning. Battery was charging and holding its charge well, almost suspiciously well...but I don't usually have my eyes glued to the display.

    Again though, charge won't go to the last bar. Normally it rarely ever charges fully but this time I feel like it just won't fully charge.

    I got my hands on a basic OBD II code reader, and it says there are no fault codes.

    I guess my next step is to get the mini-VCI cable and techstream?
     
  9. SFO

    SFO Senior Member

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    Most likely the best plan, and be sure to leave the 12v connected so as not to reset/erase the stored OBD2 codes (DTCs)
     
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  10. dolj

    dolj Senior Member

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    If by the second sentence (quoted above) you mean to imply that in the past it has been common to see the top bar (green) illuminated, then this is abnormal, except in long downhill runs. Normal behavior is that the battery controller attempts to keep the car at around the 6th bar (the top blue bar) most of the time and very rarely venturing into the green bars. It likes to reserve these two bars so there is space if you do a long downhill or a lot of long highway braking.

    If you are doing long downhills and not seeing the top bar filled, it is just indicative of the state of your battery.
     
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  11. Lexus Mark

    Lexus Mark New Member

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    I have a 2010 Lexus RX450h that keeps throwing the check hybrid system light.

    First, if there is a Lexus website for dealing with hybrid batteries, please point me in the right direction.

    Second, I pulled the hybrid battery and tested all of the cells. They are supposed to be about 9.6 volts each, but I'm getting 10.35 to 10.4 volts on most of the cells. There are a few cells reading at 10.2 or 10.1 volts. Before I replace the low voltage cells, I'm wondering if there is a way to test the cells under load in my garage? Or does anyone know a reputable shop in the greater LA area?

    Thanks,
    Mark
     
  12. MCCOHENS

    MCCOHENS Member

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    You can try the torque pro or Dr Prius with a bluetooth OBD reader. That will get you some basic info on the system and let you reset the system. May just be from getting overworked in the mountains.
     
  13. mr_guy_mann

    mr_guy_mann Senior Member

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    Hello & welcome to PriusChat.

    I don't know the details on the Highlander - RX hybrid system but it's similar to the Prius.

    There are dozens of possible faults that can trigger a "service hybrid system" message. You should scan all of the systems on your car with a capable scantool to see what diagnostic trouble codes are present.

    Most budget scantools (including many used at chain repair shops) can only talk to "some" ecu's - typically engine control, ABS, maybe airbag. They can't pull codes or data from other systems like the hybrid control.

    IF there is a problem with the High Voltage battery, the "easiest" first diagnostic step is to use a scantool that can datalog (record data) to monitor battery voltages while driving the car. Problems begin to show when the battery is stressed by acceleration and deceleration (discharging & charging).

    You can use the search function here (and on the web) for Dr Prius. That's an app that uses a Bluetooth adapter that connects to the car's OBD2 port. Dr Prius is designed to monitor HV battery data on Toyota hybrids. (It can also pull "some" hybrid system codes - IDK about the RX).

    Google turned up "clublexus.com" , which has a subforum specifically for 2010-2015 RX450H.

    Good luck.

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