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Attn Scangauge jockeys: when should I switch to HV for mpg?

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by wheezyglider, Aug 1, 2012.

  1. wheezyglider

    wheezyglider Active Member

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    Like the ordinary Prius, PiP was designed so you can "just drive it" and do quite well on efficiency. And like the ordinary Prius, a little extra attention to technique can bring big efficiency wins. PiP's extra trick is that judicious use of the HV/EV button seems to result in even higher MPG. My question to PiP experts is: can we come up with some simple rules of thumb for when HV is clearly more efficient than EV, and vice-versa?

    So far consensus is that on hills and freeways HV mode is better because using both ICE and battery is more efficient than using either alone would be. Q: Can I know from the HSI alone when a hill is steep enough to switch from EV to HV? Like if the EV demand bar is over 50% or something simple like that?

    What about on a flat with no wind. At what MPH would manually switching to HV be clearly better than EV alone?

    I guess in order to know that we'd need to compare (rate of gas consumption + net rate of kWh draw) in HV mode with (kWh draw) in EV mode for various situations. And we have some rough equivalency of gallons to kWh (maybe 33.4 kWh /gallon). I'd make a bosh of the calculations, but I bet some of you scangauge jockeys have been doing this. So give us your pithy wisdom, please!
     
    DCDave likes this.
  2. Allannde

    Allannde Just a Senior

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    I am surprised that no one has jumped in to respond before now. I have a ScanGauge (two actually so I can follow eight things, not just four). This will not be "pithy".

    The only simple rule I have discovered is that when I know that a trip, including all of its parts before the next charge will be more than the EV range, I start out in HV with a full charge.

    Not only do I preserve most of the EV charge doing this, I get really good mpg. Then when the distance to home is about the same as the remaining EV charge, I switch to EV. So far, my over all mpg is well above 100. Your results will vary depending on the trip length and speed at which you drive. My trips vary from 6 to 50 miles long and I stay at around 35 mph when I can. We don't have a lot of freeways around here.
     
    dave77 likes this.
  3. priuskitty

    priuskitty PIP FAN

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    how about this? HV= 50.0 miles per gallon
    EV= 3kw/ 33.4 kw/gallon= 11.13 x 10.6 EV = 118.0 miles per gallon
    Now I understand the 95.0mpge that the EPA states since it's not really 3kw due to losses in the charging process.

    never mind:(
     
  4. chesleyn

    chesleyn Active Member

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    Wheezyglider -- instead of speed of switch to HV, I prefer load on transmission. If I know I'm going up a hill and accelerating from a red light, HV would be more efficient. EV is way more efficient for maintaining speed versus accelerating. Just my opinion.

    Also, I have a SG2, but am only using SoC and RPM right now. Haven't delved into all the codes yet. Anyone else using codes please let me know which ones you find the most useful. I'd like to have one for transmission load.
     
  5. Jimbo69ny

    Jimbo69ny Active Member

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    The way I look at it is this, electricity is cheaper (for me its free) than gas so I try to use ev around town exclusively. If I use up all my ev range then Ill go hv.

    On long trips I go hv the whole way and save ev for the very end. I try to time it so that ev is depleted by the time I get to my destination, then I recharge.

    I find that works well for me.
     
    Andyprius # 1 likes this.
  6. Three60guy

    Three60guy -->All around guy<-- (360 = round) get it?

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    Ding Ding. That's what I do too. Works great for me too. ahem..... for longer trips. But if I know the trip will be local within the EV range I will stay on EV.
     
  7. Allannde

    Allannde Just a Senior

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    I watch 8. I have two SG2s. The non xGauges are MPH because it is more accurate than the dash reading, RPM, VLT to keep track of my 12v battery, and FWT to watch my coolant temp (this shows that the ICE cuts off at 130 degrees and it shows when the ICE is thoroughly warm, 185 degrees). The xGauges I watch are SOC, RmF or room temp for the temp inside the car to compare with the outside temp, Flv or fuel level which is in % and is more accurate than the "guess gauge" in the dash, and BtT or traction battery temp which is VERY interesting and good to know.

    I was surprised to watch how closely the traction battery temp compares to the outside temp. It may rise ten degrees during use and charging. What I watch for is anomalies. Anything out of the ordinary means get it to the shop quick before the problem spreads.
     
    Chazz8 likes this.
  8. mozdzen

    mozdzen Active Member

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    "So far, my over all mpg is well above 100." What really counts is what is your mpg when just using gasoline?
    BTW - what is your EV/ICE percentages? When I'm just using HV, I average about 60 mpg. I think people are looking to optimize that HV number with distortions from EV driving. - at least I am.
     
  9. chesleyn

    chesleyn Active Member

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    I too average 60 with HV only. Good call.