Traction battery - what exactly causes the triangle

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Tbox, Sep 16, 2019.

  1. Tbox

    Tbox Junior Member

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    Hey there all!

    So I have had my 04 Prius for over a year now, and I did a reconditioning using Hybrid automotives grid charging system a year ago. Well, it's dead again as expected. This time, I am trying to be thorough, try a couple new things.

    I started with a full charge. Then onto load testing. I actually wrote a program that uses a voltage sensor on a raspberry pi to graph and record the exact measurements I need. I actually conducted a capacitance test--i tested each module at 100w until it hit 7vdc exactly. I setup my programming system to record the initial voltage before a load, the exact measurements as soon as a load is introduced, and the final time in minutes/seconds when it hits 7vdc. This has given me a much better understanding of where each module is.

    Now my question.. I would like to play around with pairing modules(for each bank that the Prius reads) based on voltage and capacitance. My question is, does anyone know what the Prius looks for to throw up the red triangle? Is it just a difference on voltage between the banks?

    Thank you!
     
  2. jerrymildred

    jerrymildred Senior Member

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    There are a boatload of things in the battery that will bring up a triangle of death. Partial list:
    overheated inverter
    overheated battery
    bad connections on bus bars
    too far out of balance
    bad resistance readings
    bad connection at ECU
    bad sensor wires
    etc.
     
  3. sam spade 2

    sam spade 2 Senior Member

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    They might be new to YOU......but likely have been done before......with similar results: Dead again, as expected.
    I hope you enjoy tinkering with it because you won't be accomplishing anything particularly useful.
    Once a battery is truly dead, it can't be "saved".
     
  4. TMR-JWAP

    TMR-JWAP Senior Member

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    Tbox,

    I would like to play around with pairing modules

    jerry has a pretty good list there.
    sam, as usual, is a party pooper/buzz kill

    I take this as you're interested in experimenting a bit with your battery and you currently aren't really concerned about long term success. So allow me to help you...

    The P0A80 code (replace the hybrid battery) is triggered when the voltage difference between the highest block and lowest block exceed the threshold determined by Toyota. Most people say its ~1.3 volts. Personally, my experiments have shown it to be variable depending on battery load. In reality, it doesn't really matter. Each module is made of (6) 1.2 volt cells. The ECU is essentially looking for a bad cell, because if one cell in a module fails, it typically drops the module to about 6.3 volts. At that point, any significant load applied will drop that modules voltage hard and fast.

    Pairing modules can be done, but all it takes is one module with one weak cell to trigger the threshold. This is why it's much more important to have 28 modules that are well balanced (capacity wise) with each other. The module with the lowest capacity is the one that's going to limit your battery, regardless of the condition of the others.
     
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  5. Tbox

    Tbox Junior Member

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    Thanks for the info!

    Thanks, but I'm fine tinkering with the $300 Prius. I did the balancing a year ago and it lasted until now. If doing that every 6 months to a year will keep the car running, it's fine by me.

    Thank you for the in depth response. I'm an electrical engineer by trade, so this stuff really interests me. The info about looking for a failed cell; don't know why I didn't think about that before. I knew the construction of the modules/pack, and that makes sense. I don't have any failed cells right now, just an imbalanced pack that's causing the triangle.

    I basically want to figure out the prime way to pair the modules together to maximize the outcome of the reconditioning. Thank you again!
     
  6. ChapmanF

    ChapmanF Senior Member

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    Getting back to this question: the car will set specific trouble codes that tell why it put up the red triangle. There are in the ballpark of a hundred of these possibilities, distinguishable by the codes you can read out, so the question "what exactly causes" is not quite ripe yet when you're just looking at the glowing triangle and haven't read the codes.

    But moving ahead, once you have read the codes, the page that starts each code's workup section in the repair manual (more info) has a box at the top containing what's called the "detection condition" for that code.

    You'll find the "detection condition" to be the exact answer to the question you're posing here. (Edit: well, for some codes, the detection condition might only be given as "Toyota proprietary", but for the rest, it's the exact answer to the question.)
     
  7. TMR-JWAP

    TMR-JWAP Senior Member

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    Tbox,

    I have previously experimented with pairing modules. Using the charger/dischargers I have, I would perform several charge/discharge cycles of each module, documenting the results of each cycle. The hobby chargers record the exact mAh capacity of each module on the discharge portion. Once satisfied they were "restored" as well as reasonable feasible, put them in numerical order. (replace any real outliers) and then pair #1 with #28, #2 with #27 and so on. This put the overall capacity of the pairs fairly close. I made #1/#28 block 1, then the next set was block 14, and just worked my way toward the center.

    The battery worked fine and is still in operation in the blue 2005 prius we sold to my son's friend a few months ago. That battery has been going about 2 years now I think. Maybe more. After looking at my records, I got the battery around May of 2017, so I would guess it was within a couple months that it was repaired and installed in the blue 2005. 2 years is pretty close. Not bad for a rebuild......
     
  8. strawbrad

    strawbrad http://minnesotahybridbatteries.com

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    My work car is at 16 months and 32K on a rebuild of the original battery and still going strong. It's a 2005 that went from 230K to 262K.
     
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  9. Tbox

    Tbox Junior Member

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    This is on par with what I was thinking. Thank you so much for taking the time to respond.
     
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  10. sam spade 2

    sam spade 2 Senior Member

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    Typically there will be diminishing returns every time you do the balancing/"reconditioning".......because the cells are then a year older and there IS a limit. Honestly there is.
     
  11. ericbecky

    ericbecky Hybrid Battery Hero

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    Are you logging the battery data live in the car and then analyzing the results with a graphing program?
    For instance using the Torque Pro app and Google sheets.

    This can give you better insight where to focus your efforts.
     
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  12. Tbox

    Tbox Junior Member

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    Hey there. So after a couple weeks and finding time to do it all, I finished my rebuild. I did a full charge, identified the bad ones, and conducted a full charge/discharge cycle(all 3 discharge ranges). Then I went and did the load testing again, recording the capacity of each. I paired them all up to get an equal capacity for each bank (lowest with highest, and so on). The only difference is I put the higher end ones in the middle and worked outwards.

    My question for you is, do you know how the bank voltages are taken?(as in, which test points does it use? The ring terminals with sending wires on every other module to the overall negative, or between each ring terminal?) I would like to make sure I pair these up correctly so the computer sees them as such.

    Thank you!
     
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