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Plug-In Prius grille-blocking

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by john1701a, Oct 10, 2012.

  1. john1701a

    john1701a Prius Guru

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    The practice of grille-blocking for Prius dates back a number of years now. It is done to reduce warm-up time and to extend heat-retention time. Both result in the improvement of efficiency & emissions during the winter months.

    Lots of real-world data exists for the second & third generation liftback models of Prius, but there isn't anything yet for the first plug-in.

    This new thread was created to collect that information...


    My commute (fast route) to work is 3 blocks of suburb driving, 9 miles of 70 mph highway, then the remaining 6.5 miles at speeds below 60 mph.

    I trigger the engine at the second block by toggling the HV/EV button. Entry onto the highway and the entire distance in the fast section in EV-BOOST mode, which usually delivers an average of 115 MPG. At the slowdown point, I noted the coolant temperature had risen to 172°F with the outside temperature at 34°F and the grille not blocked yet.

    Unfortunately, I didn't note what the coolant high-temperature was back when it was still summer while driving that same route. Oh well. 34°F is quite warm for winter in Minnesota anyway. It will get much, much colder.

    Anywho, the next 5.5 miles of driving were all in EV mode, with the engine off. That meant the coolant would cool fairly quick without any of the grille blocked. To my delight, it didn't too much. When the engine did eventually start back up, the temperature was 118°F.

    While driving that final stretch, I watch the temperature rise to 132°F and the overall efficiency drop to 155 MPG.


    More info to come, stay tuned.
     
  2. bisco

    bisco cookie crumbler

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    is the grille different than gen III? iow, will blocking technique/materials be different?
     
  3. benalexe

    benalexe Member

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    What is EV-Boost mode?
     
  4. Paradox

    Paradox Prius Enthusiast / Moderator
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    When you are still in EV mode but going above 62mph and the engine triggers. It's not another mode you select using a button or anything.
     
  5. john1701a

    john1701a Prius Guru

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    Here's yesterday's observations, without the grille blocked yet:

    It was 43°F outside. Traffic on the 70 mph stretch was pretty routine, except for the big trunk merging out at the 9-mile mark. That caused me to slow down a half-mile sooner, to 60 mph... which caused the engine to shut off. At that point, the coolant had warmed up to 175°F.

    I almost made it the 16-mile mark (specifically to 15.9) entirely in EV mode before running out of electricity. The coolant temperature had cooled down to 118°F by then.

    A few minutes later, arriving at my destination with coolant warmed back up to the point where the engine shut back off. The act of running brought the temperature up to 132°F and topped off the battery-pack enough to allow electric-only driving in HV mode. And I did, to the ramp and up to my usual parking spot without the engine. There, the display said I had traveled a total of 16.7 miles and had an overall average of 163 MPG.
     
  6. drinnovation

    drinnovation EREV for EVER!

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    Thanks for the data..
    Is this the same trip you used to get 250MPG on before? or are you going faster?
    Curious what was the average speed.
    do you have an OBDII or other logger that would make understanding temp/speeed easier.
     
  7. john1701a

    john1701a Prius Guru

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    Today's observations were intriguing.

    Starting out at 34°F outside, I thought it would closely resemble the first day's data collecting. Instead, the coolant temperature was a little cooler and the engine wasn't needed anymore once reaching the slowdown point. I drove along the 70 mph stretch with commute traffic, noting 163°F at the usual the 9.5-mile mark where it changes to 55 mph. Then the system automatically switched to EV from EV-BOOST, remaining like that all the way until I parked. There was enough electricity available to complete the journey without gas. That was unexpected. What a nice surprise.

    At that point (16.7 miles total), the coolant temperature had dropped to 107°F. That means if I would have desired warmth from the heater, the engine would have started specifically for that purpose, since the threshold is 114°F. Fortunately if it does run, some EV distance is replenished too. That's a nice side-benefit from the warming process.

    Anywho, the outcome was quite pleasing. The overall average was 192 MPG. Now, I'm more curious than ever about the effect grille-blocking will have.
     
  8. john1701a

    john1701a Prius Guru

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    Yes, it's the same old drive. No, I don't have a logger. External influences make detail a challenge to follow anyway. Traffic varies too much. The MPG swings in the warm season were all over the place. Fortunately, once you exceed 150 MPG, the difference doesn't matter anyway. You can just observe a large sampling to identify a pattern.

    More to come. Stay tuned.
     
  9. slcMPG

    slcMPG Member

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    Do you have an engine block heater? What temp is your car in the morning?

    Your commute sounds a lot like mine. I have about 1 mile then freeway for 10 miles, then 3 miles to the office. I can drive 60-65 on the freeway portion. With the deals on the PIP I am thinking of picking one up.
     
  10. john1701a

    john1701a Prius Guru

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    No block heater, just an insulated attached garage. So, the car is a little bit warmer than the outside temperature.

    Another variable that may be more of an influence as winter approaches could be the warming of the battery-pack itself. Recharging results in heat. So if you set the timer to finish just prior to leaving, you could take advantage of a battery-pack that isn't cold.

    As for getting one, you'd be in for quite a treat. Upgrading from a classic to a plug-in would be quite big step all at once. That would be very exciting.
     
  11. 9G-man

    9G-man Senior Member

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    Your choice to use blended/"EV boost", for the 70mph highway stretch of drive intrigues me. From the stance of how would things be different if you just drove it in HV mode, or if it were driven in EV under 62 mph.

    Im sure you have a strategy behind this choice, that would be informative for you to explain.

    -Being in blended mode is what is possibly boosting your MPG for the 70mph stretch, vs. being in just HV mode.

    It allows you to arrive at work just as your EV range is fully depleted. Vs. arriving at work with EV range still remaining.

    -Being in blended mode, above 62MPH is allowing the engine run, to restore your EV range once it is warmed up, vs. being in just HV mode, where it would not.

    -Being above 62 mph is preventing all your EV range from being blown on the highway. (since you have EV mode selected.)

    Now it will be neat to see IF grill blocking will further enhance these things. So far it seems the desire for heater warmth will be the only thing playing a factor as to if the ICE comes on..
     
  12. bisco

    bisco cookie crumbler

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    i came off the highway last night on the way home with 6 miles of ev left and about the same distance home. hit the ev button with the heat at 72 and 40 outside. engine never came back on and nice and warm all the way. seems pretty darned efficient!
     
  13. slcMPG

    slcMPG Member

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    Can you explain "EV boost" vs HV? Aren't they the same? When you get below 62 in HV and glide the ICE still turns off, right?

    Also, John are you able to charge at work?
     
  14. john1701a

    john1701a Prius Guru

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    EV boost offers heavy draw from the battery-pack. On the 70 mph stretch, I see +100 MPG in that mode.

    HV is just the regular Prius hybrid mode, drawing much less electricity. The result is around 50 MPG.

    The two modes are distinguished by the EV/HV toggle button, allowing you specify how the plug-supplied electricity is used. In the case of winter heat needs, that is likely to prove handy.

    Yup, it's great. I'm especially excited to know that ChargePoint is going through a major upgrade this weekend and more charging-stations at the ramp will be installed next month.
     
  15. 9G-man

    9G-man Senior Member

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    "ev boost" is john's term for 'blended mode'. Being in EV mode above 62 mph, where the ICE is forced to run but at a low rpm, while still using battery power to also move the car.(results in 100MPG highspeed travel for a short duration) vs.. being in HV mode where there is no battery power being used to move the car..and you're getting maybe 60Mpg

    "gliding'' occurs in HV mode below 46 mph where the ICE doesn't turn and no power is going between he battery/motor. Also, below 46mph in HV mode, with minimal pedal pressure (below HSI centerline) you can run fully electric up to a lower demand threshold. Stealth mode in days past.

    The PiP makes understanding how the a Pruis works in HV mode less common. But it's useful to know.
     
  16. slcMPG

    slcMPG Member

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    Thanks. I understand the "regular" Prius HV mode pretty well or think I do (stealth, warp stealth, super highway mode etc) . I just never knew that when the EV button was pressed you get more pack assist. I always though that once the ICE was on you more or less had a Prius with a bigger battery. So, this opens up a lot of options/strategies with the PIP while on the Highway.
     
  17. ukr2

    ukr2 Senior Member

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    I went back to the Manual. 2.2 Instrument Cluster, page 268
    I wish Toyota would explain the modes better. Therefore, this is what I understand.

    When in EV Mode and the ICE starts, for whatever reason, the Hybrid System Indicator Car symbol with the EV just shows the outline of the Car. John is calling this EV Boost, other call it Blended Mode. It's where, after the ICE is warm, the ICE is powering the PIP with the assistance of the Battery Motor. This produces 100+ mpg because it uses up Battery Miles to Boost ICE Gas mpg.

    When in HV Mode, the Hybrid System Indicator display is split with the Car symbol on the left side of the middle line. If the ICE is warm and the bar is on the left, the ICE will stop and EV will indicate the Battery Motor is powering the PIP. When to the right of the middle, the EV will change to the outline of the Car, meaning the ICE started and is powering the PIP.

    When manually switching from EV to HV mode, the PIP remembers the Battery Miles status, the ICE starts and the Battery Motor poweres the PIP while the ICE warms up. After warm, the ICE powers the PIP AND restores the Battery Miles to the state that it was before warmup. Thus you get the ICE 50-60 mpg, but you have a Battery with more Miles than in EV Boost mode.

    Deciding which mode to use should be based on getting you to your charging location with Battery Miles used up, switched automatically to HV mode and using some of the rest of the Battery. Practice makes us smarter.
     
  18. john1701a

    john1701a Prius Guru

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    Yesterday, as usual, I fired up the engine prior to climbing up the ramp onto the 70 mph highway. It was 45°F outside. Traffic was flowing just under the speed limit. There was no need for the heater. At the 9-mark, traffic slowed and the engine shut off... automatically swapping the system to EV mode from EV-BOOST. The coolant temperature was 168°F. To my delight, it was another one of those commutes where the engine never restarted. In fact, I finished the 16.7-mile drive this time with 0.1 miles remaining. The result was a pleasing 192 MPG. Coolant had cooled to 100°F. Now, I'm more curious than ever what the results will be after blocking the lower-grille entirely.

    Today was forecast to be the warmest day we'll see here in Minnesota for a long time. That equated to 57°F on the morning commute. I toggled the HV/EV button to start the engine. It shut off at the 9.5-mile mark. Coolant temperature got up to 168°F. The remainder of the trip wasn't the usual all EV though. Unlike my other days of data collection, switching from the 55 mph road to 50 mph included a hard acceleration. The engine ran for roughly 5 seconds. That caused coolant to rise from 136 to 139°F. The remainder of the 16.7-mile route was with just electricity. There was 0.5 miles left upon parking. The average was 198 MPG. Coolant had dropped to 121°F. My curiosity about winter is definitely rising.
     
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  19. john1701a

    john1701a Prius Guru

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    It snowed over lunch today. By the time I left work this evening, the temperature had risen to a balmy 39°F but was windy as heck. I needed to use the heater at some point, since the windows would eventually fog up.

    With the weather front that had just passed through, the forecast for the next two weeks was for temperatures mostly in the 40's. Time to block the lower-grille. That meant this commute from work was my one opportunity to observe the system still exposed in action.

    As expected, it automatically bounced between the coolant levels we've become quite familiar with. The engine started, then ran until it hit 130°F. Driving proceeded as usual in EV, with the heater set to 76°F and the fan on low. I had the seat-warmer set to low too. When the coolant dropped below 114°F, the engine fired up again. That cycle happened 3 times along my 17.5 mile drive home.

    The end result was 127 MPG. That's quite good. I'm really curious about the heat-retention the lower-grille now blocked will provide, especially when the real cold arrives here in Minnesota.
     
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  20. Electric Charge

    Electric Charge Active Member

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    Do you have any pics of how you are blocking the grill? Being in a snowy area myself, would definitely like to try this if it helps. Never gave this any thought before, but knowing that school busses in this area do the same thing, it must be effective in my area.