Effect of 12-volt battery on mpg: 6mpg difference? Why?

Discussion in 'Gen 3 Prius Fuel Economy' started by Robert Holt, Jun 10, 2017.

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  1. Grit

    Grit Senior Member

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    Better mpg- less tread contact on road so less energy required to spin the tires. Tires decreases in weight also with outter wear flying off.
     
    #21 Grit, Jul 26, 2019
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    I think too, the 17" stock rims impose a penalty cus they're heavier and they move the mass out further, so more inertial forces at play.
     
    #22 Mendel Leisk, Jul 26, 2019
  3. Robert Holt

    Robert Holt Senior Member

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    I have read that as tires wear off their outer layer of rubber, the mileage will typically increase due to less thick rubber resulting in less hysteresis losses. That seems sensible to me given the lower mileage issues with thick-walled tires like run-flats.
    I have also read, but cannot confirm, that the rubber compound is somewhat harder close to the belts and carcass than it is on the outer surface of the tire. Anecdotally, I seem to notice decreased dry-pavement grip and more likely squealing of tires during hard cornering when the tread is worn down noticeably. Clearly there is more danger-of Aquaplaning when your tread is worn and the pavement has a layer of standing water, and I am always careful to replace well before the “wear bars” molded into the base of the tread, become visually apparent.
    However, the decrease in weight due to having less rubber on the outer skin of the wheel would just affect the energy needed to accelerate and decelerate the wheel, but I do not think the weight would directly affect energy needed at a steady, constant speed driving regime, other than the very slight proportional decrease in overall weight of the vehicle, which clearly does affect mileage. Hmmm.
     
    #23 Robert Holt, Aug 1, 2019
  4. andreimontreal

    andreimontreal Active Member

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    How do you compare these numbers? Which one means what? When is the battery good/when bad?

    What is Acc? Ready I suppose is push start twice no brake?
     
    #24 andreimontreal, Dec 19, 2019
  5. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    If you have your foot on the brake when you hit Start, you are in Ready. A light saying Ready should come on. (I have never owned a Gen 3) In Ready, your DC to DC converter is working and you should get about 14 volts on the meter.

    If you do not have your foot on the brake the dash should light up when you press start but not the Ready light. In ACC your 12 voly system should be under load, but powered only by the 12 battery, you hope for a meter of at least 12 volts, ideally over 12.5

    When off, your car is under a very light load and the meter should be over 12.5 volts.
     
    #25 JimboPalmer, Dec 19, 2019
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  6. ChapmanF

    ChapmanF Senior Member

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    Just to get the whole sequence in one place: Foot off brake, ONE button push ⇒ ACC, the dash doesn't light up, but a few selected accessories like the radio will work. All power is coming from the 12 volt battery.

    Foot off brake, TWO button pushes ⇒ ON. The dash lights up and pretty much all the 12 volt devices in the car are powered. All the power is still coming from the 12 volt battery.

    Foot ON brake, one button push ⇒ READY. The READY light on the dash is lit and the dash lights up, and the car can be driven. The 12 volt battery is being charged, not supplying power, and all power is coming from the traction battery and the engine running as needed.
     
    #26 ChapmanF, Dec 19, 2019
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  7. ASRDogman

    ASRDogman Senior Member

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    Don't you own a 2012 Prius V? That is a Generation 3... Or did I miss read???
     
    #27 ASRDogman, Dec 19, 2019
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  8. Prodigyplace

    Prodigyplace 2025 Camry XLE FWD

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    It is a Gen 1 Prius v. ;) Of course there is no Gen 2 for the US, let alone a Gen 3.
     
    #28 Prodigyplace, Dec 19, 2019
  9. ASRDogman

    ASRDogman Senior Member

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    So, 2012 is the first year of the "V"?
    Even though the engine and drive train etc., are based on the 3rd Generation Prius?

     
    #29 ASRDogman, Dec 19, 2019
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  10. Prodigyplace

    Prodigyplace 2025 Camry XLE FWD

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    Well here we call the PiP a Gen 1 Plugin and the Prime a Gen 2 plugin. They are based off Gen 3 & 4 respectively.

    upload_2019-12-19_13-6-40.png
     
    #30 Prodigyplace, Dec 19, 2019
  11. ASRDogman

    ASRDogman Senior Member

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    Okay, gotcha... Thanks

     
    #31 ASRDogman, Dec 19, 2019
  12. Mendel Leisk

    Mendel Leisk Senior Member

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    That seems confusing as all heck. How about a Gen 3 Plug-In, and Gen 4 Plug-In. That's what they are.
     
    #32 Mendel Leisk, Dec 19, 2019
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  13. Prodigyplace

    Prodigyplace 2025 Camry XLE FWD

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    I am sure it was Danny's decision.
     
    #33 Prodigyplace, Dec 19, 2019
  14. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    If he had numbered them Gen 3 plug-in and Gen 4 plug-in, we would have folks wondering where Gen 2 plug-ins were. (no one can find anything about Gen 1)
     
    #34 JimboPalmer, Dec 19, 2019
  15. ASRDogman

    ASRDogman Senior Member

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    It's a Toyota mystery! :)
     
    #35 ASRDogman, Dec 19, 2019
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