Brake Burning Smell after steep downhill

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by HaiImBrian, Dec 23, 2018.

  1. fuzzy1

    fuzzy1 Senior Member

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    Correction to my previous number: battery charge limit for Gen3 is 27 kW, vs Gen2's 25 kW limit: MG1 rating? | PriusChat
    And as various other threads have pointed out, max charge rate is sometimes reduced for temperature or other reasons, and also declines as the battery reaches whatever the Prius sets as 'full'.

    I don't recall ever seeing any mention of the total combined electrical and engine braking capacity. But it makes sense that it it isn't the same as the two separate elements combined. MG1 doesn't seemed sized big enough for both, though I haven't tried any detailed testing & computation.

    Also, the braking capacity doesn't necessarily remain constant. From personal experience on my most common long steep descent, B mode does fully control speed at first when using both regen and engine braking. But when the battery fills, the ICE spins up sharply (as it trades out battery charging for engine braking), while total braking capacity seems to drop a bit. If my initial speed is a bit too high (e.g. full PSL instead of ~10 mph slower), the car starts to roll a bit faster. Though I could be tricked by slope changes.

    And then, D, B, and CC mode braking use different combinations and levels.
     
  2. johnHRP

    johnHRP Junior Member

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    Brake smell after getting hot from driving downhill is normal. As long as you do not start getting brake fade, it is normal. pads get burned and disc gets glazed and it is normal. Overtime, these materials are fading away. The only dangerous trouble if the brake fluid is boiling and you lost braking completely. That's why it is recommended to brake flush every 2-5 years depends on how much you use the brake. In Toyota, brake fluid is rarely got moisture on it, not like Chrysler or GM. In Europe, All Toyota has 2 years interval, in USA, you are lucky if you ever change it after 20 years.
     
  3. sam spade 2

    sam spade 2 Senior Member

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    Sorry John but that is BAD advice.
    It is NOT "normal".....unless maybe you are going down a steep mountain grade and started out too fast.
    These hybrids can create a LOT of "active" braking using the electric drive motors and the gas engine.
    IF the friction brakes overheat, either the driver is doing something wrong or there is something mechanical that needs to be fixed.
    Brakes smelling HOT is NOT normal.
     
    #43 sam spade 2, Sep 10, 2020
    Last edited: Sep 10, 2020
  4. ASRDogman

    ASRDogman Senior Member

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    The wheels don't have motors...
     
  5. sam spade 2

    sam spade 2 Senior Member

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    Edited.
    Just to make you happy.
     
  6. ASRDogman

    ASRDogman Senior Member

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    Brake fluid doesn't really boil. It would be the moisture in it that would boil.
    "Standard" change time for dot 3 is 2 years, but as you said, most people don't do it...
     
  7. ASRDogman

    ASRDogman Senior Member

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    :rolleyes::barefoot::censored:


     
  8. sam spade 2

    sam spade 2 Senior Member

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    Now it's my turn.
    ANY liquid has a boiling point temperature.
    Can we just stop this pointless sniping, please ?
     
  9. ASRDogman

    ASRDogman Senior Member

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    I am NOT "sniping", you are, and you started it...
     
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