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EV mode above 42 mph?

Discussion in 'Gen 2 Prius Technical Discussion' started by yardman 49, May 3, 2009.

  1. yardman 49

    yardman 49 Active Member

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    Hello all:

    The last few days temperatures here in Northern KY have returned to more seasonable levels. Due to this and my 2009 beginning to break in, the Prius is averaging almost 48 mpg on this last tank.

    I've recently started to notice a (very nice) new trend: sometimes above 42 mph, the car will go into EV mode (yellow arrows only). It only happens when the traction battery is happy (SOC in "green bar" mode or close to it), and there is only a very light load on the car (basically just wind resistance, very little or no grade, ICE fully warmed up, not much heat or AC demand).

    I thought that EV mode could only happen below 42 mph.??? FYI, I have made no modifications to my car.

    This makes me wish for a larger traction battery. Here in Northern KY it's quite hilly. On trips with a lot of downhill runs, it's quite easy to charge up the traction battery. I can see where a larger battery would help those of us who live in the hills to recapture more of the lost energy that we give up when going down hills. (I suppose that it wouldn't benefit "flatlanders" as much.)
     
    #1 yardman 49, May 3, 2009
  2. F8L

    F8L Protecting Habitat & AG Lands

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    Could your speedometer be off a bit? Worn tires etc.

    What was the highest speed you noticed this at?
     
    #2 F8L, May 3, 2009
  3. TheForce

    TheForce Stop War! Lets Rave! Make Love!

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    As long as your SOC is high and your coolant temp is above 159F the Prius will use electric only at speeds greater than 42MPH but the engine will still turn but it wont burn gas.

    I have a Hymotion battery installed and I can do all electric on the highway at about 50MPH on level ground. The battery would only last about 20-30 miles at those speeds though.
     
    #3 TheForce, May 3, 2009
  4. yardman 49

    yardman 49 Active Member

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    Vehicle:
    2009 Prius
    New 2009, only about 5 weeks old.

    Today it happened at about 53 mph or so. In the colder weather, and then again during the "hot" spell we had a couple of weeks bac, there were times when it seemed that it "almost" happened. In other words, I'd be on the freeway, from 55 to 65 mph in glide mode, and just the yellow lines would appear for a moment, just prior to the orange ICE lines showing up also.

    The car is running great, so I'm not complaining :). For living in a hilly area, this tank and the last tank are averaging 48 mpg on the MFG. I'm not doing anything special other than keeping my tires at 40/38.

    I'm just wondering if this is normal when the temperature is ideal, and the ECUs sense that the traction battery has some extra energy that can be used up.

    Or possibly Toyota was experimenting with some new programming on the 2009s?
     
    #4 yardman 49, May 3, 2009
  5. yardman 49

    yardman 49 Active Member

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    Hey, thanks Force! I figured that it must have something to do with high SOC and a happy ICE. That's probably why I just started really becoming aware of it with the current mild weather.

    How does the engine turn without burning gas? Are the valves held open to relieve the compression? And is this what is referred to as "warp stealth" mode?
     
    #5 yardman 49, May 3, 2009
  6. donee

    donee New Member

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    Hi Yardman...,

    Yes, that is what is called warp stealth. No, the valves operate as normal, and the engine just pumps air through to the exhaust. I imagine they might operate the variable valve timing to limit the air flow pumped, to avoid cooling the catalytic converters. Its wastful, compared to a pure EV, but less wasteful then combusting gas at an engine speed that is inefficient.

    On one of my routes there is a downhill for about 3/4's of a mile. I maintain 53 mph on it, with yellow arrows for the whole length. Then as the road flattens out, I push on the peddle a little bit, the engine lights up, and back into super highway mode at 70 mpg...
     
    #6 donee, May 3, 2009
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