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HV/EV button (taking advantage of it)

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by john1701a, May 2, 2012.

  1. john1701a

    john1701a Prius Guru

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    Whoa!

    I had no idea the difference would be that obvious. :rockon:

    Yesterday, I took the "along the river" route to work. It's 17.2 miles long with a top speed of 55 mph on some roads that are quite scenic. The purpose of that particular drive was to go as far as I possibly could as far as I could using only EV accelerating as fast as possible. That extra push from the battery resulted in a drop of maximum range from 14.1 to 13.0 miles. But that electricity scarifice prevents you from holding up any traffic. You accelerate at the same speed as everyone else. When reaching the depletion point, the engine started. It's not the ideal, since using the hybrid system can be more efficient overall than electricy-only driving... especially with a battery-pack that's 4.4 kWh. The result was 250 MPG.

    Today, I took advantage of the HV/EV button. Taking the same route, I fired up the engine when the first need for acceleration came up. I briskly accelerated, knowing the engine running optimally will end up recharging the battery-pack a little bit as a result. After all, that's the point of a FULL hybrid. The system focuses on overall efficiency, not that of the moment. Once warmed up, I pressed the button again to shut the engine off. It was now available for a quick on & off later. That came when a steep hill climb was needed. Then things got interesting. MPG will unexpectedly high, close to 250 and there was plenty of EV available. Later when I arrived at my parking spot, there was 1.3 miles still remaining. And to my delight, on the display it said 310 MPG.

    The HV/EV button allowed me to use less electricity and less gas. :whoo:

    My expectations weren't to see so much of an improvement.

    That was amazing!
     
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  2. TPinho

    TPinho Junior Member

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    You are right. That's why I'm getting 14.8 to 15.1 EV miles after charge.
     
  3. ultraseven

    ultraseven New Member

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    So is the moral of the story to keep HV on? I usually run on EV by default, then once the EV portion runs out it kicks into HV mode. Overall on a 25 mi one way commute I've been getting about 75 - 85 mpg depending on speed and how much lead was on my foot.

    I will try it this evening and see if the overall mpg goes up. Overall if I end up using less gas while still depleting the EV portion to 0% on my commute it will make the most sense.
     
  4. 9G-man

    9G-man Senior Member

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    Glad you posted this. I've experience the exact same thing with strategic use of HV versus just letting EV run out and continuing on in HV.
    I make a 16 mile trip to a marina where I have a boat very often. It's not only the distance but the hilly GA terrain that prevents traveling the whole thing in EV.
    So, I've been experimenting with different combinations of EV and HV.
    Last night I traveled the distance with a 340 MPG average by using HV to climb the steep hills and switch back EV for level driving and especially the downhills because the regen increases and stacks my EV range.
    (Just as Paradox has demonstrated and reported...I've only recently been convinced how really great a technique this is. Thanks Paradox!)

    Previously I've gotten 160MPG and 180 MPG on that same trip with techniques that involved depleting EV range early, or climbing hills. What a difference!
    I was knocked out at the end of trip, looking at the display totals when I shut down.

    My kids get into the whole strategy thing too, coaching and reminding me when they think I should switch. : )

    I think the warm up cycle is important too if you plan on using HV. Don't wait until you need the ICE to goto HV, because it still mush warm up, and will still use EV range during the warmup. Go to HV in a low demand area and let it warmup while its still efficient, then you can climb the hills with gas only, which seems more efficient.

    I've also conclude its best to switch to HV manually on a long trip, just before EV range is depleted, to you can regen and build EV range back.
    If you let the automatic switchover to HV happen, after EV range is exausted, you cant it back.
     
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  5. wiggleman

    wiggleman Junior Member

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    I would put it on EV for short trips in the city. For longer trips, HV is better.
     
  6. 9G-man

    9G-man Senior Member

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    Well sure, of course that is the basic idea behind a plug in hybrid.
    But I think the point of this thread is techniques to handle a trip moderately beyond the PiP's full EV range.

    I was in a situation today where 5 seconds of HV usage (with 0.1 mile of EV range) got me an additional mile of EV travel. How? That 5 seconds of HV got me up a hill that I then regened down and gained more EV range and traveled all the way home. Had I not done it the whole distance would have been in HV using gas.

    My current tank is at 102 MPG and 340 miles traveld. That is mostly work roundtrips at 94 miles each, and local EV driving.
     
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  7. john1701a

    john1701a Prius Guru

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    Nope.

    The advice is to fire up the engine to take advantage of the hybrid system when you are driving beyond the EV capacity available. Once the coolant warms to 130°F, the engine on & off is surprisingly quick and you gain a little bit of EV in the process.

    Today, I pushed the button to start the engine, then drove the warm-up distance while in HV mode.

    Tomorrow, I'll push the button, but only stay in HV mode for a few seconds. Switching back to EV mode right away will draw from the battery more, which is ok for me since I ended up at my destination with unused EV today. That should result in higher MPG.


    99 MPG for me at 545 miles.
     
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  8. ukr2

    ukr2 Senior Member

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    Since my 1st Fillup, I've been Resetting Trip A and EV Display 1 for each driving segment and leaving Trip B and EV Display 2 for Fillup stats. My one-way distance to work is 14.6 miles, 55 mph max. Average speed 25 - 30 mph.

    I usually turn on HV and let the ICE warmup on a flat stretch in the middle of the distance. I stay in HV until the available EV Battery is within 2 miles of the GPS Miles to Destination. That way I get enough EV to get within a half mile of destination with the regen when back in EV mode. Then I hope to run out of battery and auto-switch to HV to use up some of the HV battery.

    Sometimes, I forget and stay in HV too long and have a little EV battery left when I get there.

    What is Strange is on 2 different days going in the same direction, I had 0.3 EV Battery when I got there, but one day I got 195 mpg and the other day I got 366 mpg. Why the difference ???

    Then going the other direction and having auto-switched a half mile before destination, one day I got 278 mpg, another day I got 107 mpg and the other day I got 346 mpg. And I'm driving the same way each time.

    I can't yet figure out why the big swing, but I'll keep recording the data.
     
  9. HillCountryEVer

    HillCountryEVer New Member

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    Very cool John! Do you think you might be able to create a video capturing this scenario?

    Thanks again for the post -
    :)
     
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  10. john1701a

    john1701a Prius Guru

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    Yup. I'm really looking forward to that too. It's this exact drive I did a few months ago with the 2010:



    I'll do it with the display screen capture, then later sometime the ScanGauge.
     
  11. John in LB

    John in LB Life is good

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    What's that white stuff on the left and right side of the road? I've never seen that before... :eek:
     
  12. bilofsky

    bilofsky Privolting Member

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    Occasionally there's something white on the mountain peaks around here. Wonder if that's the same stuff.

    [​IMG] Is getting the most EV miles the same as maximizing MPG? For example, when getting on the freeway, should I use HV to accelerate and burn a lot of gas, and save the EV for slower driving, or use EV and then switch to HV at 50 or 55 mph?

    I sold my last manual transmission car 25 years ago, but it feels like I'm back shifting by hand again.
     
  13. john1701a

    john1701a Prius Guru

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    As planned, I used the button today to fire up the engine, but then switched back to EV mode a few seconds later. That left the Prius in "enhanced HV mode" until the engine was warmed up (130°F), then it automatically because electric-only driving.

    It was a "just drive it" experience, making no effort whatsoever to keep the engine from starting back up, even when climbing up the long steep hill. Turns out, that wasn't necessary. There was no need for that much power. In fact, I was a bit bummed when I finally reached the river crossing.

    Merging onto the highway, I dropped the pedal to the floor to start the engine. Turns out though, traffic was only traveling at 52 mph and it was downhill. So, that was likely wasted gas.

    Upon reaching my parking spot, there was 0.2 miles of EV capacity left... and to my delight the efficiency was higher. The result today was 320 MPG.

    That's only a difference of 0.0017 gallons of gas (from the 310 MPG yesterday), well inside the margin-of-error for measurement. So, far more sampling would be needed to really nail down the improvement. But that's rather pointless, since even getting just the 250 MPG from never using the button is great anyway.
     
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  14. john1701a

    john1701a Prius Guru

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    Nope, which my initial observations have confirmed.

    Sometimes less EV can equate to higher MPG.

    Being a hybrid has advantages. This seems to be a nice example of that.
     
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  15. mikenewmediary

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    John,
    I normally switrch to HV when I jump on the highway, but noticed when I go into HV I lose .5 -.8 off of the battery. It looks like the engine returns about .3, within a few minutes.

    Today, I hit HV about .5 mile before entering the highway, same result with the drop in EV.(flat road condition)

    Do you know why this happens, or if there is a way to avoid this loss?

    Today, I exited off the highway with what I lost, but had to use coasting to achieve this.

    Mike
     
  16. mitch672

    mitch672 Technology Geek

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    Mike,

    I have observed the same issue, and I'm fairly certain the PiP is going through the "ICE" warmup cycle, which is spinning the engine, but keeping the load fairly light, until the engine has reached the 130 degree temp... Once it's warmed up, the EV mile # pretty much stays the same, or will actually go up with some downhill coasting.

    The trick is to use the ICE sooner, to have it warmed up and availbe before your EV range is nearly gone.... Because at that point, you can't regen EV miles (once its switched to HV only)
     
  17. john1701a

    john1701a Prius Guru

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    Prius places a very high priority on emission-reduction. That means it will sacrifice efficiency for the sake of being cleaner. In the case of PHV, it generously draws from the battery-pack to allow the engine to run at a low RPM... even when accelerating hard. It's pretty easy to see that with a ScanGauge too.

    You can't avoid the situation. It can only be minimized by seeking out opportunities to warmup the engine under less straining situations.
     
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  18. 9G-man

    9G-man Senior Member

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    I love this car. It's insane how efficient HV mode is, and with strategic use of the button..... With 11.4 miles EV range and a 47 mile trip to work with rush hour traffic, I got 89 MPG for the trip

    And that's 96 % freeway

    The best I could ever hope for in my Gen II was 59 MPG with perfect technique. So 11 miles of ev range capacity gained me 30 mpg, by me choosing when to use it. AWESOME

    On a trip like that my strategy is EV to and from interstate, HV for highspeed portion and then switching between EV/HV during slow speed travel, relying on HV to climb hills and EV for flat, decents and braking, which gains me more EV range thru regen. And not exausting my EV range completely until the end of the drive.
     
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  19. iRun26.2

    iRun26.2 New Member

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    Most people think about buying the PiP because of the efficiency and fun of driving in EV mode. The HV mode doesn't get the credit it deserves...it is an amazing improvement in of itself!

    (The HV mode efficiency should, by itself, sell the car)
     
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  20. ppimd

    ppimd Member

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    It appears that fast acceleration early in ev or hv mode starts the ice, which then stays on if switched to ev, to warm itself up. It stays on until it decides to turn off, independent of your toggling hv/ev. In demanding condition ice switches on then off in ev.