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Car sat for 18 months. Dead cells in battery?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by splosion, Jan 28, 2023.

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  1. splosion

    splosion Junior Member

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    Vehicle:
    2007 Prius
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    II
    Hi! I’ve had a 2007 sitting for 18 months, the result of not having enough time to address a misfiring engine. Now when I try to start the car, the car won’t enter ready mode or start the engine and the display reads “Problem”

    OBD2 voltages on 13/15 packs reads 15.3v, and the readout for the other two oscillates between two sets of values: 17.3v & 2.83v, and -0.4v & 4.7. A few months before my engine problems, I had the battery replaced with all new cells.

    Are battery problems now another nail in my car’s coffin? Thanks for any advice.


     
    #1 splosion, Jan 28, 2023
  2. bisco

    bisco cookie crumbler

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    is the 12v okay? where did you get the new cells? 18 months is a long time to sit
     
    #2 bisco, Jan 28, 2023
  3. SFO

    SFO Senior Member

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    Inspect the HV battery 'voltage sense harness' for tab/wire corrosion, and the HV battery ECU socket for pin corrosion.

    Take pictures and post them here if unsure. How far from Columbia SC are you?

    FYI : You're moderated until you've posted 5 times.
     
    #3 SFO, Jan 28, 2023
  4. TMR-JWAP

    TMR-JWAP Senior Member

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    It's very likely those modules are dead due to corrosion in the ecu socket where the voltage sensing harness plugs in.
    Unfortunately, it's not uncommon for batteries that have sat for long periods. I see it in quite a few core batteries that have sat at a salvage yard for extended periods.
     
    #4 TMR-JWAP, Jan 28, 2023
  5. Blakwolf

    Blakwolf New Member

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    Location:
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    Other Hybrid
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    I'm seeing a similar Dr. Prius output where all of the voltages were fluctuating wildly on a car that had probably sat for a similar length of time to yours. However, after replacing the 12V battery that could not keep a charge, it did allow me to drive the car for a few months, even with fluctuating voltages. After the temperature dipped below 60 degrees this winter, the car would no longer get to READY. I took my HV battery out and the modules all measured 7.88-7.89 V. I did discover that my #1 voltage sensing wire had completely snapped, but I couldn't be certain if that happened during the disassembly. I have not put it back into the car yet, but I'm hopeful resoldering the voltage sensing connector and replacing busbars will help things.

    I would also recommend examining the voltage sensing harness and the ecu socket for your battery.
     
    #5 Blakwolf, Jan 28, 2023
    douglasjre likes this.
  6. douglasjre

    douglasjre Senior Member

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    ----USA----
    Test individual cells w dig meter. Clean bus bars if corroded. Recharge cells w charger if needed
     
    #6 douglasjre, Jan 29, 2023
  7. douglasjre

    douglasjre Senior Member

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    You don't have to replace the bus bars so come in clear vinegar and baking soda and scrub with a nylon brush
     
    #7 douglasjre, Jan 29, 2023
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