Short trip tips?

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

  1. Raytheeagle

    Raytheeagle Senior Member

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    Probably a beautiful day at Skywalker ranch though:).

    Gotta come out sometime soon and get a break from it(y).
     
  2. Prodigyplace

    Prodigyplace Senior Member

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    You must not be living right. We had a good bit of sun here in Virginia today BTW, in order to be really where it's at, you need to be south ogf the Mason Dixon line. @Raytheeagle is judging the east by states north of that line.
     
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  3. Raytheeagle

    Raytheeagle Senior Member

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    Oh I’ve lived in the south (not too far from where you reside) and the summers are hot and humid:sick:.

    6 years was enough south of the Mason Dixon Line (y).
     
  4. Prodigyplace

    Prodigyplace Senior Member

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  5. Raytheeagle

    Raytheeagle Senior Member

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  6. TMR-JWAP

    TMR-JWAP Senior Member

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    On the flip side of that, I recently headed up a visit to one of our sister facilities. Myself and 4 others with individual luggage etc for three day/two nights. We rented a new suburban and drove from Columbia, SC to Birmingham, Alabama. The trip was about 350 miles each way. That monster averaged 27 mpg. It's pretty impressive what modern engine controls are doing. It was running on 4 cylinders the majority of time while on the highway.
     
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  7. Prodigyplace

    Prodigyplace Senior Member

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    You didn't have to send that rain HERE! ;)
    (Actually, our garden thanks you.)
     
  8. pasadena_commut

    pasadena_commut Junior Member

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    Getting back on subject here...

    The fuel gauge hit half full (half empty?) at almost exactly 200 miles. Fuel gauges are rarely linear though, anybody know off the top of their head how many gallons that would be? (Roughly, of course). Maybe I will just fill it up on the way out this morning, just to know.

    Having watched the energy display for a week now it is evident that this car takes a very long time to reach normal operating temperature, at least on the route I'm driving. It never takes less than 10m for the car's mpg/ 5m display to reach the point where it stops rising.

    My HCH1 warmed up faster, but it wouldn't shut off the motor at stops until it was at full operating temperature. So I could tell where that point was, and it was at about 5m. Coincidentally the car before that, a Mazda Protege5 also reached full operating temperature at the same stop light, which was evident because the idling RPM would fall suddenly when it shifted from open to closed loop.

    If I had to guess the problem is all the stops. The motor shuts off at each and every one of them, even the very first light. So not only is it not warming up, given the tiny motor and exposed surfaces it is likely cooling off substantially at each stop. It also isn't heating up the catalytic converters very quickly. The HCH1 I used to drive had the same fast cooling problem, but it was only evident in the winter. When it came to a stop with the heat on the motor would shut down and the air coming out of the ducts would start cooling off. If the stop was long enough the temperature gauge would also fall. The Prius has no such gauges though, so the stock display isn't going to give up this information. The proper cable has been ordered, once that is in I will be able to monitor temperatures to see better what is going on.

    I'm also wondering a little about the heat setting. It isn't set to auto, and the temp is 72F. There is no specific "heat/cool" switch and I wonder if maybe the car is drawing heat off the motor to warm the cabin which also contributes to the slow warm up. (It would do that at a stop even if the motor is off.)
     
  9. Prodigyplace

    Prodigyplace Senior Member

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    I assume you have a Prime even though your profile says 2007 Prius. The Prime has an electric heat pump for heating & cooling. The Gen 4 has an electric air conditioner but heats from engine coolant & exhaust.
    I am surprised the Prime would shut off the ICE before it is warmed up. Other Prii keep the ICE running to achieve the primary task of running efficiently to minimize pollution.

    I ansurprised the HCH1 couls warm up in 5 meters. That is only a little more than 16 feet.;)
     
  10. srellim234

    srellim234 Senior Member

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    The OP being in southern California, I'm assuming he means 5 miles, not 5 meters.
     
  11. Prodigyplace

    Prodigyplace Senior Member

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    m is the abbrerviation for meters. mi is the abbreviation for miles. Both are used in the US.
     
  12. srellim234

    srellim234 Senior Member

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    True, but understanding what people really mean sometimes requires common sense and deduction too. No internal combustion engine on any car is going to warm up in just 16 feet of operation after starting. Besides, he clearly stated he's driving a 2007 in the OP.
     
  13. Prodigyplace

    Prodigyplace Senior Member

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    Sorry, I got my threads confused thinking this was a Prime thread.
     
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  14. srellim234

    srellim234 Senior Member

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    It's ok. It's very uncharacteristic to see you that picky here. I figured there was some legitimate reason.:)
     
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  15. pasadena_commut

    pasadena_commut Junior Member

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    Yes I dropped the "i", it was miles not meters.

    Two new pieces of data.

    Filled it up to find out what half a tank was in gallons. Of course pulling into the station it dropped one tick below half full.
    208.8 mi at 5.4 gallon so only 38.7 mpg. The running mpg (reset at the beginning of that) was 39.5mpg. The display
    was 2% optimistic or the odometer was off 2%. The dealer put on new tires (Bridgestone Ecopia), I need to check that they are the right size (which could easily shift things by 2%) but even if they are, they are also new, and Toyota may have calibrated things for tires with 50% wear (or something like that). Anyway, the display and actual mpg were pretty close. Looks like 5 gallons is a pretty good approximation for gas used to half full.

    Measured the car's 12V battery voltage 5 hours after it was driven for 10 miles. This used the built in diagnostics to get to the "Vehicle Signal Check" page. That showed 12.1V. Pressed power button one more time to get to ACC (low fan running, no radio, no cabin lights) and it fell to 11.3 before rebounding to 11.7. That does not look like a good 12V to me, it looks like one which is about to die. Never mind that the dealer's million point checklist (you know the kind) showed a good 12V battery. No problems starting it yet though. Have not yet checked it right after turning the car off. Not sure yet if it isn't charging to full, if it cannot hold a charge, or if there is some left "on" in the car which is discharging it. No cabin lights on when the car is off. Is there anything else that might be turned on drawing power from the battery?

    It occurs to me that if the 12V is really bad the car may be running its equivalent of an alternator (an inverter?) much more than usual, which could depress the mpg some.
     
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  16. srellim234

    srellim234 Senior Member

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    To be perfectly honest I believe you're overthinking this. For the type of driving you describe, you are right in the ballpark mileage-wise. If you get the opportunity, try running it out this way on the 210 and then back home. I think you'll find the car between 43 and 46 mpg on that run, much the same as I find with mine when I head over your way.
     
  17. fuzzy1

    fuzzy1 Senior Member

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    .[/quote]While this seems bad, it also seems to be typical of Prii, which are not particularly good at keeping the 12V fully charged. Especially with just short trips. Consider trying a battery tender to get it topped up.

    Prii do run into MPG and various weird problems when the 12V gets too low and near death:
    Weird stuff happening? MPGs dropping? Test The Battery | PriusChat
    but that generally happens with lower batteries than you have. A number of folks who preemptively replaced the battery at this point, found no great improvement.
     
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  18. pasadena_commut

    pasadena_commut Junior Member

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    Wait, that wasn't what I meant! "m" was minutes, not miles or meters. The point I was trying to make was that other cars I have owned reached stable operating conditions in about the same elapsed time of 5 minutes of warm up, but this Prius doesn't. I think because given the stop/go nature of the trip and the long times the engine is off it is only actively warming up half as much. For the other two cars that 5 minutes was about 1.4 miles. The Prius seems to need around 3 miles to warm up.
    [/QUOTE]

    Measured the voltages two more times for this table:


    time V1 V2min V2final
    1 300 12.1 11.3 11.7
    2 1260 12.1 11.2 11.6
    3 3 12.4 11.7 11.8


    time is in minutes since the car was turned off
    V1 is the first diagnostic voltage
    V2min is the lowest diagnostic voltage on entering ACC-ON mode,
    this only lasts for a second
    V2final is the stable diagnostic voltage in ACC-ON mode, after the voltage
    stops fluctuating.

    Last line is after driving ~7.5miles to work.

    Pretty sure the battery voltage shouldn't be below 12 in ACC-ON mode. (Lowest fan setting, display on, nothing else explicitly on.)
     
    #58 pasadena_commut, May 6, 2019
    Last edited: May 6, 2019
  19. Prodigyplace

    Prodigyplace Senior Member

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    About 3 miles for warm-up is normal for my Gen 4 Prius too. I really doubt your 12 volt battery is hurting your fuel economy.

    The Prius us designed first to be low polluting so the engine runs until it gets to the optimal running temperature. For Gen t some of the coolant is even stored i a thermal flask to help retain heat when not running. The Prius fuel economy is really a secondary result of being low polluting.

    Ambient temperature, terrain, & how aggressive the car is driven greatly affect efficiency. In fact, unlike traditional cars, the economy is higher when driven in city traffic. The Prius is not designed for the impatient driver.
     
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  20. LeoLucid

    LeoLucid New Member

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    Don't try to EV/hypermile in town or stop and go traffic, you're losing fuel economy if you're crawling to work on ICE, gotta warm her up. Probably wouldn't hurt to cover all the new car bases either, filters/fluids/tire pressure/so on.

    And don't let these guys get in your head, welcome to the squad!
     
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