2002 Prius gas mileage decrease

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by tumbleweed, Nov 23, 2005.

  1. tumbleweed

    tumbleweed Senior Member

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    Yes absolutely. The batteries, both the HV and the 12V, consist of individual cells and you can certainly have a problem with individual cells. If you told the dealer that you smelled battery acid and they told you to check your tires you need to find a different dealer. Talk to the Prius technician or the service manager not the guy behind the desk that takes your order.

    If you post your location someone on here may be able to point you to a dealer with a good Prius technician.

    It could be that your decrease in mileage is just due to cold weather and winter gas, but that doesn't mean you don't have a battery problem too. If it were me I would take it to a good Prius tech and have both batteries and charging systems checked, don't wait to long.

    Let us know what you find.
     
    #1 tumbleweed, Nov 23, 2005
  2. DanMan32

    DanMan32 Senior Member

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    A bad cell should flag a DTC. as each module is monitored by temp and voltage. At least the 2G is, I think the classics do too.

    But an HV battery with low charge capacity would cause loss of accelerating power, and lower efficiency.

    If it is the battery, you might be able to get one cheaper from salvage.

    How many miles on the car?
     
    #2 DanMan32, Nov 23, 2005
  3. tochatihu

    tochatihu Senior Member

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    Yes loiband, say where you are. If you are up to it, use the owner's manual to tell you how to remove the fabric covers and take a good look at the 12 volt battery. I would not regard the high voltage (HV) battery recharge you report as suspect, without more info.

    Can you determine if the HV battery ventilation fan is running more than you are accustomed to? That fan should surely be on if the HV battery is running hot.

    Some pesky, rare mpg killers are dragging rear brake shoes from self-adjusters gone bad or a parking brake pedal just set one click. For these I desire to know if the brake drums feel hot.

    DanMan, there are a slew of HV battery DTCs in the classic Prius, and as far as I can tell they are all related to battery state of charge (ensemble or at the module level), as determined by the battery ECU's cleverness. A temperature excursion that is not controlled by ventilation should trigger safe mode operation, substantial reduction in perceived power, and one or more warning displays on the screen.
     
    #3 tochatihu, Nov 23, 2005
  4. Frank Hudon

    Frank Hudon Senior Member

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    there is also a DTC on the HV battery regarding leakage of some cells in the battery. It was to do with sealing the battery. Can't remember the number of the service bulletin.
     
    #4 Frank Hudon, Nov 23, 2005
  5. tochatihu

    tochatihu Senior Member

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    Good point Frank. Loiband, was the SSC 40G battery modification done on this vehicle?
     
    #5 tochatihu, Nov 23, 2005
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