Hybrid battery ohms

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Raphael Muscarelle, Jun 21, 2019.

  1. Raphael Muscarelle

    Raphael Muscarelle Active Member

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    Hello. I have been wondering about my hybrid battery status so I started looking at it since it seemed to charge fast and drain fast. I have found this far 2 banks with bouncing ohms one goes up to 127 and back to what the rest are about 20.0.
    My first guess is oxidation on bus.
    Second might be bad cells. Screenshot_20190621-154953~2.jpeg

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  2. TMR-JWAP

    TMR-JWAP Senior Member

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    First may actually be corrosion of the voltage sensing wire/tab where the wire crimps to the tab or at the ecu pins. It would be highly unusual to have the actual IR of a module fluctuate rapidly. A small crack across the crimp area, or even more likely, corrosion on the pins/connector plug where the sensor harness plugs into the ecu. You probably want to check this soon, (especially since it's 2 adjacent blocks that read off) as corrosion in that area has lead to catastrophic failure like sparks and smoke and molten pins, etc. This is probably more common on the Gen 2 and 1, but maybe early Gen 3's are heading that way now. I guess it's not really an ECU on the Gen 3, more like just a voltage sensing module or something.
     
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  3. ChapmanF

    ChapmanF Senior Member

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    My guesses would have bad cells higher than oxidation on the bus, at least if the bus connections haven't been disturbed by somebody's repair work.

    If you take apart an old battery, the bus links can look really gnarly with corrosion everywhere you can see, but they won't usually look that way beneath the nuts and over the terminal studs. When the nuts are properly torqued, the pressure is enough to keep those contact areas pretty much gas-tight and shiny.

    I have known bad battery cells to really behave as if something is making intermittent connection inside. (I haven't had this experience specifically with Prius modules, but with ordinary cylindrical NiMHs used in other settings.)
     
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  4. Raphael Muscarelle

    Raphael Muscarelle Active Member

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  5. Raphael Muscarelle

    Raphael Muscarelle Active Member

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    Didn't mention center of battery is operating about 5 degree warmer then the rest

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  6. Raphael Muscarelle

    Raphael Muscarelle Active Member

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    I guess I'll replace the 4 cells and see what happens. Maybe replace bus bars with new

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  7. TMR-JWAP

    TMR-JWAP Senior Member

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    The middle of a pack is pretty much always the warmest. Did you inspect the plug and pins at the end of the voltage sensor harness?
     
  8. Raphael Muscarelle

    Raphael Muscarelle Active Member

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    I will when I take the pack out to put different cells in.
    I'm sure this has been doing this for many miles only know because I started to look.

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  9. jerrymildred

    jerrymildred Senior Member

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    I would recommend NOT putting in replacement cells until you've eliminated the corrosion and wire integrity possibilities mentioned by @TMR-JWAP and @ChapmanF. As mentioned, the middle of the pack normally runs a little hotter than the ends. Replacing good cells can lead to creating problems and definitely creates extra work.
     
  10. Mendel Leisk

    Mendel Leisk Senior Member

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  11. TMR-JWAP

    TMR-JWAP Senior Member

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    If you're really determined to swap modules, why not just switch those four with 4 located at the end of the assembly. That way, if the problem follows to the new position, you could at least be more confident it's a module issue. If the problem stays at the same place, then you know it's wiring, plug or the ecu(ish) thing. I just have a hard time accepting that you have multiple modules with bouncing IR values. Seems much more likely its not a module issue, but more of a connection/continuity/sensing issue.
     
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  12. mjoo

    mjoo Senior Member

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    Yes

    Pixel XL ?
     
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  13. jerrymildred

    jerrymildred Senior Member

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    That's a really good suggestion, if you're eager to swap modules.

    @Raphael Muscarelle, it's been a while since I've been in there, but I seem to remember that you have to take off the buss bars and sensor wires in order to take out the modules, so you might as well look at them while you're at it. Might just save some time and money. ;)
     
  14. Raphael Muscarelle

    Raphael Muscarelle Active Member

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    I do agree. Just same 2 banks are consistently slightly lower voltage then the others. That is reason I'm swapping them. Also gonna put new bus bar plats on. At that time if bouncing ohms doesn't go away then I'll look at other possibilities.

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  15. Raphael Muscarelle

    Raphael Muscarelle Active Member

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    Sure case cover comes off in car.

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  16. Raphael Muscarelle

    Raphael Muscarelle Active Member

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    Cells are bolted from underneath so have to take it out to work on it anyway.

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  17. Raphael Muscarelle

    Raphael Muscarelle Active Member

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    Not that Im determined to do anything. Battery is getting weak and going through tests bank 5 and 6 are consistently lower voltage. Granted by just a little.

    I'm kinda thinking I'm suffering from battery memory tho. I have 220k miles bought car with 65k 2 years 7 months ago from dealer. I think dealer messed with battery since vent piping is missing. So about 95% of my driving is highway at 70ish mph. Battery always in 50-65% range only once in a long while it would hit 66% to light up next bar.

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  18. TMR-JWAP

    TMR-JWAP Senior Member

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    The vent tubing is a bit unusual on the Gen 3 models. The Gen 3 batteries I've disassembled are about 50/50 when it comes to having the tubes installed. I've probably pulled apart about 25 or 30. I have no idea why they're like that, as every one I've had has been 100% original. Gen 1 and Gen 2 are 100%, they always have them. Gen 3? Not so much, but I'm not sure why.
     
  19. Raphael Muscarelle

    Raphael Muscarelle Active Member

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    That's interesting batteries must have been assembled on Friday then

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  20. Raphael Muscarelle

    Raphael Muscarelle Active Member

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    Found broken tamper seal just now tho

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