Short trip tips?

Discussion in 'Gen 2 Prius Fuel Economy' started by pasadena_commut, May 2, 2019.

  1. pasadena_commut

    pasadena_commut Junior Member

    Joined:
    May 2, 2019
    59
    20
    0
    Location:
    Southern California
    Vehicle:
    2007 Prius
    Model:
    N/A
    The dealer put on new tires (Ecopias) and changed all the fluids. The oil still has that clear/new appearance.

    I was not trying to hypermile but I did notice something peculiar the other day. There is about 3/4 or 1 mile (never measured it carefully) downhill stretch on the way home. A couple of days ago I finally figured out the pedal pressure to make the display arrows go black and I hit all the lights right for once. SOC fell two bars over that distance and maybe 4 minutes. The car was on, the radio was on, but the headlights weren't. So not a huge power draw, I would think. I would have thought that a healthy 12V alone could have supplied that current, but I think this one is very much on the way out. That much SOC charge drop for so little load does not give me a warm and fuzzy feeling about the big battery.

    Regarding the 12V battery, using the "signal check method" in ACC-ON first thing in the morning (car sat overnight, ~14 hours) shows a voltage of just 11.1V. Seems mighty low for 12V lead acid battery!
     
  2. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    81,625
    35,289
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    no a/c on? yes, you probably should replace the 12v
     
  3. Mendel Leisk

    Mendel Leisk Obtuse Angler

    Joined:
    Oct 17, 2010
    34,673
    23,618
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Pop the hood at night, then in the morning: check battery at jump point, with a digital multimeter. Better yet, something like Solar BA5, an electronic load tester. Post your findings.
     
  4. pasadena_commut

    pasadena_commut Junior Member

    Joined:
    May 2, 2019
    59
    20
    0
    Location:
    Southern California
    Vehicle:
    2007 Prius
    Model:
    N/A
    12.39-12.40V after drive home
    12.24V 17h later

    Car completely off both times. Obviously this battery is on its way out. Depending on the table referenced that last measurement is about 50% SOC. A healthy car would be close to 100%.

    The dealer says that if I bring it in they will load test it and if it doesn't pass, replace it. (Because the million point check list said the charging system was within spec.) Load test instructions usually say that the battery should be at at least 75% before running it, which it might be, barely, for about 2 minutes after the car gets to their location, otherwise, too low to test.

    One of the two tabs that holds the fuse box lid down is flopping around, it mostly peeled off the side of the box and is now attached only by a narrow sort of hinge at the bottom. The lid is really only held in place by the latch at the bottom and the other tab, the broken one isn't doing squat. Anybody ever fixed one of these tabs? Superglue, epoxy, or something else?
     
    bisco and Mendel Leisk like this.
  5. pasadena_commut

    pasadena_commut Junior Member

    Joined:
    May 2, 2019
    59
    20
    0
    Location:
    Southern California
    Vehicle:
    2007 Prius
    Model:
    N/A
    12V battery replaced this morning by dealer (for free). On first startup signal check showed 12.5 V and in ACC-ON it only went down to 12.2 V. Much better! Probably won't make a bit of difference in the mpg department, but will post an update if it does.

    To balance our "Carma" my wife's late 90's Accord lit its CEL the very same morning, while I was driving back from the dealer. (It was an evap system code - reseated the gas cap, cleared the CEL, and it stayed out on the next restart.)
     
    bisco likes this.
  6. pasadena_commut

    pasadena_commut Junior Member

    Joined:
    May 2, 2019
    59
    20
    0
    Location:
    Southern California
    Vehicle:
    2007 Prius
    Model:
    N/A
    Filled it again today, first full tank after new 12V battery and after the compound meter board failed and was replaced. Mostly the same commute. It was at 392 miles shortly after reaching the 1 tick mark, fill up (at the same station and pump) was 8.2 gallons, which is 47.8 mpg. This was in perfect agreement with the consumption display. Between the new battery and the new compound meter board (the one for speed, odometer, etc.) it seems most likely that the improved mpg resulted from changing the former. Others have reported this effect with weak 12V batteries before. Still, ~9mpg improvement with a new battery versus the old one is pretty amazing. I think ~48 mpg is about what this car should be doing under these conditions, when it is working right. It would be hard for it to do much better since the car spends such a large fraction of these short trips warming up.
     
  7. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    81,625
    35,289
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    agree completely
     
Loading...