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2008 prius drop in mpg.

Discussion in 'Gen 2 Prius Main Forum' started by JPP, Nov 17, 2012.

  1. JPP

    JPP Junior Member

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    Searching threads I have found a few possible problems, but need advice. I have a 2008 Prius with 88,000 miles. I have noticed a drop in my normal mpg's over the last few tanks. I used to always end up around 44-45 mpg's per tank, lately I have been averaging right at 40mpgs. Here is my question. I have read a lot about the 12 volt battery. This morning I checked it using the service screen in the car (which I just learned from this forum) and it said the volts were around 11.2. It had just sat overnight in cold temps. Should the 12volt always read 12 volts?
    Thanks
    Jeff
     
    #1 JPP, Nov 17, 2012
  2. bisco

    bisco cookie crumbler

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    it should read higher than 12 volts. you need a new battery. how long have you owned the car? mpg's drop every year this time due to cooler/colder weather and reformulated gas. all the best!
     
    #2 bisco, Nov 17, 2012
  3. fuzzy1

    fuzzy1 Senior Member

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    First, read this post: Weird stuff happening? MPGs dropping? Test The Battery

    But, I have a feeling the voltages ranges mentioned there are the traditional values for non-hybrids, and don't account for the apparent lower voltages we see on the Prius.

    For example, I'm used to seeing about 12.6V on the household's nonhybrids, and knew that the old Subaru battery was running on borrowed time. When I returned from a long trip a couple days ago, it failed to start, showing 12.15V. A battery charger fixed it for the moment, and it will be replaced shortly.

    The Prius seems to typically run at a lower voltage, I've often seen 12.2 on a nearly new battery. Readers with 11.9 and 11.8V have reported no problems, but your 11.2V seems too low. And at 4 to 5 years old, your battery is at the age where many begin having problems.

    Also, will this be your first winter in this car? MPG should already be dropping with the colder temperatures: Why mileage gets worse in winter
     
    #3 fuzzy1, Nov 17, 2012
    koolingit likes this.
  4. fuzzy1

    fuzzy1 Senior Member

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    I wrote:
    For a good Prius 12V voltage scale, see Post #16 in: only 36-37 average mpg?
     
    #4 fuzzy1, Nov 18, 2012
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