Dead Traction Battery, No ICE, probable fix

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by yups, May 13, 2020.

  1. yups

    yups Junior Member

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    Ran into problems when replacing spark plug coils with amazon aftermarket. 06 prius died after a mile and i tried to get back home. Ran traction battery to nothing, car would not move or even attempt to start.I put back old coil packs. Still dead. Jumping was no help. I called dealer to see about getting battery charged. OMG, another story..long story short.I was able to to put 8amp 12 v charger on aux battery overnight while car was still connected to 12v. In the morning, hybrid battery posted no change so I disconnected 12v and let it sit for rest of day while i tried to find grid charger.
    Later I hooked 12v back up and OBD2 to check SOC. On second try(to Start) Computer must of reset; indicate @50% SOC and car started.
    I had previously erased codes and disconnected 12v , None of that had worked...I think the 12v charge trickling into hybrid battery was the most likely fix. The 12v is less than year old...
    Hope this helps someone in similar spot.
     
  2. fotomoto

    fotomoto Senior Member

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    Sorry but charging the 12v does NOT charge the HV pack.

    You should have read the codes before erasing them.

    GOOD LUCK!
     
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  3. yups

    yups Junior Member

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    I know right? Im completely baffled. However, the only change to the system was adding current to 12v system. and it went from 1 bar to 5. Has anyone ever parked their machine and seen MFD bars increase??
    I wonder in the schematic what connection to the two systems have? Diode or transformer property's? If its like a transformer circuit, maybe it steps up in reverse. i read somewhere that the Traction pack will subsidize the 12v in certain conditions.
    Heres a crazy thot: back in the day, my ac probably got contaminated with non-hybrid conductive oil/refrigerant and now my ac unit is probably shorting/trickling electricity. Maybe that's where the connection is? there are AC codes...
     
  4. bisco

    bisco cookie crumbler

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    the 12v is kept charged by the hybrid battery through the inverter/converter when ready, but not vice versa.

    something else is going on with your hybrid battery and dash indicator, probably a bad cell
     
  5. fotomoto

    fotomoto Senior Member

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    That's one sign of failing HV battery; a more common one is quick fluctuations up and down.
     
    #5 fotomoto, May 13, 2020
    Last edited: May 13, 2020
  6. yups

    yups Junior Member

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    live TS data has consistent battery IR's and voltage's thru out the pack. Don't failing modules have aberrant readings? But hey, maybe it is the pack. Has anyone hooked up there 12v charger and seen bars rise or an increase in actual SOC%? Is it possible that a completely topped off 12v would dump current thru the inverter into a starved pack?
     
  7. bisco

    bisco cookie crumbler

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    rather than guessing, why not wait for the codes to return and read the tealeaves?
     
  8. TMR-JWAP

    TMR-JWAP Senior Member

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    The car initially discharged down to it's safety shutoff....which still has plenty of reserve to start the car. Maybe disconnecting the 12v battery for a bit caused all the ecus to reset to default values? The HV battery SOC defaults to around 50-60% until the car has a chance to relearn actual SOC. Resetting back to default makes the ecu forget everything that happened previously and it now thinks everything is good. The reserve capacity of the battery is good enough for one or two start attempts.
     
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  9. dolj

    dolj Senior Member

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    Will say it one more time. Nope didn't happen, it can't happen as there is no physical connection when the car is off. Further, even if there was a connection somehow, there is not enough potential in the 12 V battery to have any or much effect on the HV battery.

    +1 to what TMR-JWAP said ^^^, that is the was likely explanation.
     
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  10. yups

    yups Junior Member

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    Just to clarify. I disconnected 12v prior to hooking up charger. It would not start. It was only after charging 12v while it was connected. The 12v became topped off and charger went into trickle mode all while 12v was connected. I did disconnect charger prior to starting.
    Whether the charge went thru a step up transformer to change pack charge or the completely topped off 12v fed into traction pack circuit is moot. The fact is the charge in the pack increased significantly.
    I think the process is important in changing preconceived perception of: drained pack needs grid charger and or having dealer try and sell you a new pack because you ran out of gas and kept going or whatever caused ICE to fail.
     
  11. ChapmanF

    ChapmanF Senior Member

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    This:

    Simple fact, might not be getting through.

    But also this:

    That's what happened. You fooled the car into thinking it ought to try starting again. It worked out for you.

    It is likely to work out, a limited number of times.

    Don't push your luck, as you already have found out what's entailed in recharging the traction battery if you reach the point of needing to.
     
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  12. Mendel Leisk

    Mendel Leisk Senior Member

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    Just for the record, did it die due to running out of gas?
     
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