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Low mileage after hybrid battery replacement

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by pisceian, Jan 19, 2018.

  1. pisceian

    pisceian New Member

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    Location:
    Hixson, TN
    Vehicle:
    2008 Prius
    Model:
    Two
    History: 2008 prius had been acting different for a couple of months, I watched the battery and it would highly fluctuate from purple to green and I was having to fill up gas more often, i.e. mileage dropped. No warning lights but took it in and a few cells were bad so had the hybrid battery replaced. Toyota gave me a deal on it since it was just out of warranty but still $2,000.
    Now: Hybrid battery doesn't fluctuate at all, stays almost full green constantly. That's weird too, right? Mileage is 44 low (used to get 52 on nice days). It has been really cold so I would expect around 47 but not 44. I called dealer and they said no warning lights so nothing is wrong but I had no warning lights when the battery was dying. Does it just take time for the command system to learn the new battery? Like it got used to low voltage and doesn't know what to do with a brand new powerful battery yet? It's been a couple of weeks since the replacement, just bizarre that it doesn't fluctuate and times when I think it should be using the battery it's putting more into it on the screen.
    Thanks.
     
    #1 pisceian, Jan 19, 2018
  2. fotomoto

    fotomoto Senior Member

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    Yes, give it time. It's COLD right now! It's green more of the time because the ICE is running more than usual to provide heat and thus keeping the HV battery charged.
     
    #2 fotomoto, Jan 19, 2018
    WilDavis likes this.
  3. bisco

    bisco cookie crumbler

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    welcome!
    the battery should hover around 5-6 bars most of the time. how many miles have you put on it?
     
    #3 bisco, Jan 19, 2018
  4. Mendel Leisk

    Mendel Leisk Senior Member

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    Did they do anything else, maybe dropped tire pressures (if you're running them higher).
     
    #4 Mendel Leisk, Jan 19, 2018
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  5. stockdaddy

    stockdaddy Member

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    Vehicle:
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    Common things that can hurt gas mileage for Prius
    1. Cold Air (cold air is thicker than warm)
    2. Short Trips (takes time engine to get to operating temp so first 1-5 miles horrible gas mileage)
    3. Tire Air Pressure (37 back, 40 front I do)
    4. Running Heat/AC (76 summer, 68 winter work for me. 47mpg+ summer)
    5. Carrying Extra Weight, Roof Rack
     
    #5 stockdaddy, Jan 21, 2018
    WilDavis likes this.
  6. JC91006

    JC91006 Senior Member

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    I just got a replacement battery on my 2008, went from 40mpg back up to 48mpg. Stays constantly 6+ bars on the SOC screen
     
    #6 JC91006, Jan 21, 2018
  7. edthefox5

    edthefox5 Senior Member

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    Every time I have gon3 to the dealer or get the oil changed they want to mess with the tires.
    Mendel was right.

    They set the tires to door jamb pressure. Get it back up to 38
    Buy some foam pipe insulation at Loews and jam it into th3 front grill it’s freezing out if you use the heat the motor will never shut off. Block the grill.
     
    #7 edthefox5, Jan 21, 2018
  8. WilDavis

    WilDavis Senior Member

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    I did the most recent full recondition on the TractionBattery of my 2009 Gen II over the Yule holiday and I'm noticing the SoC spending more time in the 70-80% region (all green bars), however the fuel consumption hovers around the mid-40s, but gets better in the warmer months. Two things help this (1) seasonal differences in gas formula, (2) less need of heat in car, so ICE not used as much, although a/c is used more in the summer months, but the TractionBattery uses air from the cabin to keep cool (A Good Thing). All the above, plus it's difficult to calculate realistic MPG from only a few data points. Doing a long-term study over the life of the car might provide more accurate data! - hope this helps - Wil;)
     
    #8 WilDavis, Jan 21, 2018
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  9. Lucifer

    Lucifer Senior Member

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    Cycle the emergency brake several times, jack up the rear and check the spin of the rear wheels, how well does it coast, I've always replaced front bearings around 50-60,000, and as mentioned, check the air pressure.
     
    #9 Lucifer, Jan 21, 2018
    Mendel Leisk likes this.
  10. pisceian

    pisceian New Member

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    Hixson, TN
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    2008 Prius
    Model:
    Two
    Thanks all. Air pressure is fine, always make sure to refill after it's been to a shop for anything. I know it's cold but this is still not right. We've had warm days and it tries to refill the battery (that is already full) when going up a hill and it should be using the battery to help me up the hill. Even with the bad battery I never got 44-45mpg. I will wait for consistent warmer days but I am very disappointed. A new battery should be rocking MPG. Even in colder weather with the bad battery I had 47-48. Dealership said it would throw a warning code but that's BS since it never threw warnings of the battery dying. I still think they didn't connect something right or the command module isn't regulating properly.
     
    #10 pisceian, Jan 30, 2018
    Mendel Leisk likes this.
  11. fotomoto

    fotomoto Senior Member

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    You can always try a reboot by disconnecting the 12v for a few minutes. This will make the battery ECU reset its operating parameters. This method is also suggested when doing reconditioning on an old battery with a grid charger to "see" the healthier battery after the process is complete.
     
    #11 fotomoto, Jan 30, 2018
  12. Mendel Leisk

    Mendel Leisk Senior Member

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    Has winter gas been mentioned?
     
    #12 Mendel Leisk, Jan 30, 2018
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