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How far does mileage fall when new battery is needed ?

Discussion in 'Gen 3 Prius Technical Discussion' started by revhigh, Jan 16, 2013.

  1. revhigh

    revhigh MPG Enthusiast

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    Hey All !

    I averaged right around 48 MPG overall on the original tires.

    Changed to the Continental ProContact with Ecoplus at around 28,000 miles, and the mileage fell roughly 3 MPG to around 45 MPG overall.

    Now the mileage is around 40 (and sometimes a little less ... like 38), and I don't remember such a drastic drop last winter. Could the drop be due to a failing 12V battery ? The car is 24 months old, but I DO have an amp hooked up to the 12V battery since new. I'm wondering whether the amp could have hastened the battery's death, or maybe there's nothing wrong with the battery and it's just the typical winter drop. The only thing different this winter is that I have NOT blocked the lower grill as I did last winter.

    Does anybody have experience with mileage drop due to 12V battery failure ? I don't know whether it's due to winter and the non-blocked grill or battery failure.

    When the battery fails does the mileage drop ridiculously, or just a little as I'm experiencing ? I get a reading of 12.4V at the front contact points after an overnight soak. Yesterday I hooked up a battery tender trickle charger to the front contact points and it charged for about 6 hours before I had to remove it to go somewhere. Who knows how long it would have charged had I not removed it. I'm running 42/40 in the tires, and I'm religious about monitoring that.

    Car has 43000 miles, and air cleaner was changed at 30K.


    Thanks for any insight.

    REV
     
    #1 revhigh, Jan 16, 2013
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    Supply more info:

    Which Bridgestone Ecopia? EP20?

    What's the weather like of late?

    How long are your trips? Lots of short trips? Or?

    If you fully charge the 12 volt, drive the car for a few days, then hook it up to a digital multimeter, it should be reading at least 12.6 volt. Healthier would be 12.7~12.75. (Note: if you take a reading right after charger it will be inaccurate, on the high side. Due to "surface charge" or something?)

    Also, why not block the grill?
     
    #2 Mendel Leisk, Jan 16, 2013
  3. F8L

    F8L Protecting Habitat & AG Lands

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    Rev, I think you have the Continental ProContact with EcoPlus tires.

    The voltage on your 12v battery looks goo but sometimes that doesn't tell the whole story.

    Does the car seem to run more often where it would normally shut off?
     
    #3 F8L, Jan 16, 2013
  4. Mendel Leisk

    Mendel Leisk Senior Member

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    <post deleted>
     
    #4 Mendel Leisk, Jan 16, 2013
  5. revhigh

    revhigh MPG Enthusiast

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    WOW !! You are absolutely correct ! Don't know how I got that wrong ! Corrected it.

    It seems to run about the same as always ... except worse mileage. I'm guessing it's probably just the weather and the tires, and the fact that I haven't blocked the grill yet this year.

    Do you know how low MPG typically suffers if the 12V is going bad ?

    Would my amp being hooked up to the 12V cause the battery to die prematurely ?

    THe weather has actually been fairly mild this year ... probably the same as last year.

    Thanks for all the quick replies.

    REV
     
    #5 revhigh, Jan 16, 2013
  6. KK6PD

    KK6PD _ . _ . / _ _ . _

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    if it gets below 50°, your MPG's will take a hit. It sounds like it's winter! When you get in the 70's, I bet you get back to normal!
     
    #6 KK6PD, Jan 16, 2013
  7. szgabor

    szgabor Active Member

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    Not really if you were using the amp in Ready Mode .... But a few full discharge will damage the 12V which could easily happen just NOT driving for 2 week or more !!!

    Also even bad battery would not account for this loss. Let see 14.6Vx4.3A nominal charging will be about 60W which is about the same as ONE low beam light .. so anyone who tells you the battery will have such impact might suggest not running the lights !!!

    I had a Gen 3 with 42k and 3 year 3 months and the battery was getting weaker (it had two seriously low discharge by accident... ) but the car was driven almost every day 3 hours each so it was not left discharged a lot... so your use case should be just fine ... Also both extreme cold and hot condition also very bad for batteries (both 12V and HV) ...


    I see some drops although I do full blocking and monitoring temp with SG.

    In my opinion tire plus the colder weather is more likely the reason you should go back at least partial blocking during the winter .... especially if you like cozy warm car ... only turn on heating after 140F also it worth to run ECO for the first few miles the ICE will turn off about 110F instead about 140 for PWR...
     
    #7 szgabor, Jan 16, 2013
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