12v battery

Discussion in 'Gen 2 Prius Main Forum' started by Bacon_Is_A_Pooper, Jul 10, 2020.

  1. Bacon_Is_A_Pooper

    Bacon_Is_A_Pooper New Member

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    I've seen all kinds of different threads about this type of thing but I can't seem to get a clear answer, or a solution to my situation.

    I recently replaced my original 12v battery after my car would have every warning light on the dash turn on (big red triangle, check engine, (!), ABS, VSC, BRAKE) beep loudly then the car would stop or shift into neutral. The reading while driving would go from 14.2v to 11.1v and continue to drop until about 8v when the car dies, when the car drops to 12v while driving the A/C will stop working properly and only blow hot air. When i replaced the battery the car left me on the side of the highway and wouldn't even go into READY mode. paMy hybrid pack needs to be fixed according to the original owner and I have done it myself before. Now the new battery I installed is doing the same thing, it goes from 14.9v to 11.4v while driving.

    My question is, is my bad hybrid pack killing my 12v? Did I buy a bad 12v? Is there anything else it could be?
     

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  2. SFO

    SFO Senior Member

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    Welcome to PriusChat!!

    Fairly common, might need to upgrade the search skills or read a bit more in the forums.
    No.
    No, or very unlikely. You could put it on a charger or return it.
    Yes. Do you have any OBD2 codes (DTCs) that you can share with us?

    Sounds like a P0A93, and you may have a failed inverter coolant pump (or worse), when was it last replaced or inspected?
     
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  3. fotomoto

    fotomoto Senior Member

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    The prius is a HEV (hybrid electric vehicle) and the health of both (all) batteries is paramount for it to function properly.

    GOOD LUCK!
     
  4. sam spade 2

    sam spade 2 Senior Member

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    Or certainly the inverter isn't doing it's job any more.
    That device serves the function of an alternator in a conventional vehicle.
    When it fails, the battery won't charge.
     
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  5. Bacon_Is_A_Pooper

    Bacon_Is_A_Pooper New Member

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    Thanks for all the info.
    I picked up 2 inverter pumps at my local pick n pull for like $18 and changed the pump,and bled the line of any air bubbles, it has solved the battery problem, I'm going to see if Toyota sure start battery still falls under warranty, it has an 84 month warranty sticker on it.

    It was giving the P0A93 code and has been cleared, the only bit that is kinda weirding me out is my battery temp is usually running around hot, like 120+°F, the Dr. Prius app lets me turn on the fan via override but I digress. Topic for a different thread.

    Thanks everyone for all the help.
    sam spade 2
    fotomoto
    SFO
     
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  6. SFO

    SFO Senior Member

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    Have you had a chance to inspect or clean the HV battery fan near the 12v battery?
     
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  7. ChapmanF

    ChapmanF Senior Member

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    The battery isn't being charged. While driving, the car is using power from the battery, which steadily drains, until it can no longer power the car.

    The DC/DC converter is what charges the battery. It clearly works sometimes (you would never see 14.2 or 14.9 without the converter online), but it is turning itself off for some reason, at which point you get dash lights and a beep to announce that it is a known problem.

    It would be good to post all of the trouble codes retrieved when that happens; they will explain why it is shutting off.
     
  8. Bacon_Is_A_Pooper

    Bacon_Is_A_Pooper New Member

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    Yeah I cleaned it the last time I replaced a bad cell, it was dirty but still in working order
     
  9. Bacon_Is_A_Pooper

    Bacon_Is_A_Pooper New Member

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    Thanks for the info, I fixed the issue recently, battery is doing good
     
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  10. 2GenPrius

    2GenPrius Member

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    I'm having the same temp measurements as you, and I swapped out a battery pack already and my 12V was warrantied by Toyota. If I were to hazard a guess, it's because of the ambient temp increase. Running the AC full blast and maxing out the blower fan helps a bit.

    After looking and feeling the airflow setup in our gen Prius, then comparing it to other iterations of the car (3rd gen had blower directly on pack), I'm thinking there was a notable heat issue that was never dealt with. I planned to do some schematic work on adding a second blower to pull the air out of the pack, and to shroud it a bit better from when it "exits" the vehicle.
    IMG_20200712_122812 (1).jpg
    I say "exit" because if you watch and ready it in operation, it's using that little plastic interface and grill area to evacuate the heat, the only problem is that there is no exit shroud (at least mine didn't have one). I actually measured the air movement and since the top portion was not covered, it was dumping heat back into the compartment, thus raising the temp. Can't be good for the 12V, and will raise the temp of the exhaust from the fan as well.

    I have a temp gun that I've been using to monitor the intake/exhaust for the battery cooling system. I may be overthinking it, yet I look at newer gens with newer blower/exhaust fan designs so maybe there's something to it. I did notice that my battery pack likes it at 100-115F for operation. Anything else and it's too warm.
     
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