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Is it new battery time?

Discussion in 'Gen 3 Prius Main Forum' started by WNav, Mar 21, 2018.

  1. WNav

    WNav Junior Member

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    2010 Prius
    Model:
    III
    Well... is this the end for my battery? Here's a bit of history.

    Last summer, I had started getting a check hybrid system code. Mileage was about 175K. It would shut the hybrid part and keep on going with just the engine. Once I get a chance to pull over, I would reset the 12v battery and it would be fine again for a few days. It would do this once a week for 2 months. The last 4-5 months, it happened only 3-4 times, about once a month.
    Fast forward to today. It is now at 201K miles. Got on the fwy and accelerated to 50 mph. All of a sudden, I felt power loss and I cruised to the shoulder. There was still a bit of power as I press the pedal as it maintained 45-50mph for a bit. I pulled over and stopped. I tried to go but no go. Did the 12v battery reset. I was able drive about 200 ft on the shoulder and it only went up to 15-20mph. I stopped and tried to go again but no go and called the tow truck.
    Couple codes that popped up were:
    Check Hybrid System
    Low Traction Battery.

    After it was dropped off at home. I tried to start it up again and it just jerked a couple times as it tried to start but it wasnt successful.
    Does this sound like what happens at the final moments of a failed battery?
     
  2. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    A few things wrong here.

    Firstly, you cannot "shut the hybrid part and keep on going with just engine". It is not physically possible in a Toyota. The HSD requires the use of both MG's and the ICE. If the engine spins the car can move without it on electric only until the pack is depleted and then your screwed because you will need to grid-charge it.

    When you get a code, you need to read it. The check hybrid system code could be anything from a bad battery, to a loose HV isolation plate, to a bad inverter or inverter coolant pump, or loads of other things. There should be sub-codes and exact codes to say what it is.

    As your car sits now, it sounds like your gas engine is failing to start and you have depleted the traction battery so it cannot spin the engine enough to start. This is what happens when you drive it to emergency stop on electric only (what you did first), then restart and drive again to emergency stop (what you did before a tow). My guess is now you will need to have the battery grid charged to bring it up enough to start to turn the gas engine on to charge it back up. But you also have something wrong with the engine system. Could be anything as well like a bad fuel pump, clogged coils, who knows. But you have multiple problems right now and without the actual codes, everyone is guessing. The car has told you it was sick for a year, and now it is in the ICU because it wasn't cared for.
     
    Bay Stater, RMB and jerrymildred like this.
  3. WNav

    WNav Junior Member

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    Thanks for the reply.

    Thats right, I did check the code months ago and the code that only came up was P0420.

    I guess I was mistaken. I had thought the whole time when my "check hybrid system" pops up, its only the ICE that is running.

    I'll have to pull the codes and see where it leads me this time.
     
  4. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    P0420 is NOT failure in the hybrid system code. That is a catalytic converter failure, or rather below efficiency. This does actually match with what your symptoms are as this is the gas part of the gas-electric hybrid and exactly why when it died, it was the gas engine dying and you drove it dead dead on electric only.

    So you have a problem, especially in CA where they test the catalytic converter. It could be the cat, it could also be something like the O2 sensors. But you now also have a second problem completely unrelated to the first that was entirely preventable. Your HV battery is now dangerously low. So low that it won't spin the engine. This means you need to have the battery grid charged. This is much harder than it sounds. Generally dealerships have to fly in specialized equipment to do so. Expect a $1k bill at least for your 200ft of driving when the car told you "no" from the dealership. And then you're back to your actual problem, something wrong with the engine subsystems.

    If you know anyone with a Prolong charger and is very handy and good with high voltage DC, you may be able to charge 'er up slowly for free. Or by disassembling the battery and using RC chargers on each module, get it back together. Either way, a huge PITA.

    Was it only the P0420 code? Was there shaking before? Rough idles? Smoke? Has someone stolen your cat if you look under the car?
     
    Bay Stater likes this.
  5. WNav

    WNav Junior Member

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    Not with this car, but I'm familiar with another car having a low HV battery. Like you said, so low that it doesnt "start" the engine. Its kinda of like the HV battery is jump starting the engine. The battery had run low after leaving it on accessory power. I had to let it sit for 5 minutes and it eventually was able to start the engine after a couple tries.

    Yup only the P0420 code the last few months. For that one, it seemed to have gone away when the weather got colder. And even on super long drives. 300-400 miles in a day. Never came back. The only time it came back recently was when I put it in Power mode and accelerated fast.
    No rough idle. no smoke. Cat is still there. :) It did have a rough shake as it tried to start it when I got home. I didnt try again since I wanted to read the code first tomorrow. I've had that rough idle shake before on that other Prius as you try to start when its on low battery.
     
  6. Keepdriving

    Keepdriving Junior Member

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    Hmm... you got 26K after the light first came on. I'm at only about 15K since check hybrid system light first came on. I guess I can expect another 10K. :)
    Using the OBD2 scanner is so much more convenient to reset the error though.