Finished replacing booster/accumulator. Brake Bleed Next

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Trafficat, Feb 20, 2025.

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  1. ASRDogman

    ASRDogman Senior Member

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    10 amps is twice to much for the Prius 12v battery.... You could damage it.
    5 amps or less is what you're suppose to use.

     
    #21 ASRDogman, Mar 2, 2025 at 8:41 PM
  2. ChapmanF

    ChapmanF Senior Member

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    A 10-amp charger isn't something that's going to insist on forcing 10 amps through the battery. It can supply up to 10 amps; what it will supply depends on the battery's condition and state of charge.

    The car itself doesn't limit charging to a few amps; the DC/DC converter is rated 120 amps output and you can catch it putting several tens of amps into the battery right after starting, if the battery was very low. But it doesn't take very long for that flow to drop down to the single digits as the battery comes up closer to charged. What ends up determining the flow is really the voltage out of the converter and how charged the battery is.

    The car does have a temperature sensor over the battery, and it can reduce the DC/DC converter output voltage a bit if the sensor reads hot. Less current ends up flowing because of the reduction in voltage.

    When the dealer wants to supply power to sustain the car's systems while the car is ON during some important procedure, they'll hook up something like this bad boy:

    [​IMG]

    About throwing a breaker, remember your house voltage is 120 and the battery voltage is 12 (ok, more like 14, to be able to charge a 12-volt battery). A "10 amp" charger is one that can supply up to 10 amps on the output. 10 amps ✕ 14 volts is 140 watts. But for the charger to get 140 watts from the house at 120 volts takes barely over an amp. Nowhere near throwing a breaker.
     
    #22 ChapmanF, Mar 2, 2025 at 9:14 PM
    Trafficat and Brian1954 like this.
  3. Trafficat

    Trafficat Junior Member

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    Okay, so I got the Noco Genius 10, and I tried charging the battery on AGM 12V mode. It suspiciously charged from discharged to 100% really fast, within just a few minutes. I then ran the repair mode, and then charged it again. It was still suspiciously fast. Hypothesis: 12V battery is bad, and needs to be replaced.

    But I went ahead and tried to run the brake bleed with the Noco Genius 10 attached to the leads. The brake systems regular interval buzz remained high pitch which sounded better, because before the pitch got really low without the Noco attached.

    I reset the memory again, and began the brake bleed.

    Unfortunately, all was not well.

    From the rear wheels, when I did brake bleed, I got NOTHING out of them. I even totally removed the bleed valve, and nothing came out. (On a previous bleed attempt I did get probably whatever residual fluid was out of the line).

    On the front wheels, I was able to bleed them succesfully, the FIRST time. Then I was told by tech stream to bleed the stroke simulator. At first it seemed to work, I got some brake fluid out of it. I was almost even satisfied that I got a bleed, but then no more fluid came out. Techstream told me to bleed the front brakes again... but now, no fluid was coming out of them either.

    :(

    My brake pedal assistant reported to me that the brake pedal was difficult or impossible to depress at times, and when I started to bleed the front brakes the pedal became easier to depress once the fluid started.

    Hypothesis: 12V battery is still bad, so maybe it still isn't working due to the bad 12V battery. Next step on my mind is to replace the battery and try again. If that fails, I feel like I have a problem with the new parts I installed.


    Thoughts?
     
    #23 Trafficat, Mar 3, 2025 at 10:27 PM
  4. rjparker

    rjparker Tu Humilde Sirviente

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    The rear bleed is hold the pedal down and let the electric brake pump do the work. No shortcuts or "better way".
     
    #24 rjparker, Mar 4, 2025 at 1:12 AM
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