Help with Prius Plug in or Prius

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by innerpri, Sep 14, 2012.

  1. miscrms

    miscrms Plug Envious Member

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    Understood. That's a major complicating factor on both vehicles when trying to compare MPGe. It would definable be cool if they can start pulling kWh. Volt will suffer from its lower mpg in HV mode, PiP will suffer from its lower range. Both make it a poor way to estimate relative EV efficiency.

    Rob
     
  2. miscrms

    miscrms Plug Envious Member

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    I'd say that limitation also makes it very hard to gauge where you are in the pack at Volt Stats. You may be one of the more efficient drivers, but come out in the middle because MPGe is dominated by EV%?
    Rob
     
  3. John H

    John H Senior Member

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    I don't think I would be one of the more effecient drivers. I averaged 48 in the Prius as a point of reference. I honestly don't think Volt drivers worry too much about HV numbers, or MPGe, some of them (including me) have what has been coined as "gas anxiety" and don't want to use any gasoline. The discomfort of having less than 10 miles of EV range remaining and being 11 miles from your garage is .... horrific. Luckily I have a Whole Foods with a charging station 6 miles before I get to my garage.
     
  4. John H

    John H Senior Member

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    another server glitch ? I glimpsed your recalcs but then they disappeared... is PC running on a 3.3kwh battery?

    getting a second, or third, daily charge on the PiP is very rewarding.
     
  5. drinnovation

    drinnovation EREV for EVER!

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    The 3.44 you are getting or the Pip inlucude the use of gas in the 11 miles (I presume you took 11/3.2kWh).
    The gas was needed for the most energy intesnive aspects of the EPA testing, so its hard to extrapolate what the PiPs energy would be on a different test.


    MPGe on voltstats is not very useful its a mix of the users EV% and their users MPG_CS.
    Voltstats has me at 73.5 MPGe and since 10/29.11 it say I'm at 82.3, but but my computed MPGe sicne 10/29 is is 104MPGe. Last month on voltstat was 91.3 MPGe, but real computation was 130MPGe, so yes voltstats is probbly underestimating a lot of people's MPGe.
     
  6. John H

    John H Senior Member

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    drinnovation, is the 4.55mi/kWh from the spreadsheet usable? I saw something about regen creeping the number up.
     
  7. drinnovation

    drinnovation EREV for EVER!

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    How regen is counted depends on the driving mode. The PiP can "stack" regen and if then it is counted into the EV milage and does increase the apparent rate. If you go down a hill in EV mode, then switch to HV mode, you get to keep the EV regen then when you switch back to EV later you have more EV miles. .. see these threads
    My EV/HV mileage for 2 days round trip and continued updating with pics | PriusChat
    EV miles can be regenerated by PIP after EV depletion | PriusChat

    What we don't know is how often that happens or if its the only way it counts regen as EV miles.
     
  8. miscrms

    miscrms Plug Envious Member

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    I think its still there, last post on page 3.
     
  9. miscrms

    miscrms Plug Envious Member

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    Already I see a problem with my recalc ;)

    I assumed 32/35.6 mi * 10kWh AC = 8.71kWh AC for the Volt. It looks like AC full recharge is more like 12-13kWh? If the Volt mi/kWh is too low at 3.67 then that would cancel out to some extent. It seems like we don't really have a good number for that though.

    Rob
     
  10. John H

    John H Senior Member

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    I see 12kWh at the plug for a full 10.4kwh charge, so 86%, 87% seems right. Sometimes a charging session is higher than 12kWh but that is when I remote start and pre-condition the cabin while plugged-in, something I do from the phone app 10 minutes before I get back to the car depending on weather.

    The 19% difference seems to correspond with the vehicle weights. 3100 PiP, 3781 Volt, the ~4x bigger battery perhaps.

    I just did some investigation on the battery weights and I think I understand Toyota's choice of 4.4 kWh (180 lbs, 41lbs/kWh). adding another 476lbs to a Prius wouldn't help the HV mpg.

    This indicates 1.76mi/kWh for pure EV PiP operation. (6 miles / 3.4kWh from the wall). I think I am starting to understand why Prius Classic owners are skeptical of the Plug-In.

    I think the largest variable to consider here is travel speeds during EV mode for a given route. www.jurassictest.ch/GR/ seems to be a good resource but they don't have the PiP in the vehicle catalog. The Volt is listed under Opel/Ampera (but with the 16kWh battery rather than the useable 10.4kWh). priuskitty has been using the Leaf's profile but with a 3kWh battery. Would be nice to have this tool able to calculate the EV/HV consumptions for the PiP and Volt, perhaps even recommend an optimal use of EV/HV for a route based on travel speed, grade, and weather (climate loads).
     
  11. drinnovation

    drinnovation EREV for EVER!

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    Last fall my killawatt measured 12.9 for a full charge, no preconditioning with ideal temps (so TMS energy).
    When it was colder I measured 13.1 for a full charge, no preconditioning but some TMS.



    Not useful.. the 6 miles did not exhaust the battery, its just the distance during EPA testing to the first engine turn on, i.e. where is the first steep hill in the test where the battery is low enough that the ICE kicks on. It still has battery power after that (and does until 11 miles).

    I looked at the EPA data pretty carefuly and could not find a way to get a good pure EV kwh/mile estimate from it.
    What we really need is some of our own measurements on volt/PiP comparison.
     
  12. john1701a

    john1701a Prius Guru

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    I figured it wouldn't take long for the existing measures to reveal their shortcomings.

    It's nice that you now agree with me about needing something else.
     
  13. drinnovation

    drinnovation EREV for EVER!

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    My saying that we need an actual kWh/mile on some standard test is not "new". As soon as the PiP sticker was available people such as USB were saying its kWh/mile was much better and I kept pointing out that is apples and bannans comparison. I'm actually okay using MPGe, which is a unified energy measure, for overall efficiency, but Rob/John are trying to estimate electric energy usage for which they need a good kWh/mile estimate. Unfortunately there is not sufficient standard data from which to get an estimate for the OP's usage from EPA standard data. Its easy for a Volt, since its pure EV for the whole test, its the limited PHEVs that present a problem their manufactures did not release data that separates EV and ICE efficiency.

    It would be nice if EPA expanded testing to have 3-4 different test of energy used at different constant speeds, e.g. 45, 55, 65 and 75mph constant speed enegy usage.. then someone could mix/match to build profiles that matched their commute. As we see more limited PHEVs this would become a more useful set of data.
     
  14. miscrms

    miscrms Plug Envious Member

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    I agree that better EPA testing would be helpful, but it seems like the ultimate answer should come from real world test data. At best the EPA testing tries to come up with a "typical" driving profile, and predict an average efficiency from it. If real world data is compiled in sufficient volume, it should be a superior indicator of "average" performance.

    The question of actual EV drive efficiency is interesting from a technical standpoint, but it would seem like "net" efficiency across many tanks on many vehicles driven by many people in many conditions is the answer you need to get to the estimate of average expected driving experience. From that perspective, if the PiP data includes the effects of regen storage that clouds the actual EV drive efficiency but not the net efficiency needed to estimate real world driving particularly if averaged across a large sample.

    So it seems to me the main obstacles at the current time in comparing efficiency are that the PiP dataset is too small to be statistically significant, and the VoltStats dataset lacks kWh usage data.

    The modeling/simulation approach can also be useful, but its highly a function of the assumptions that go into the model. Ideally a model needs to be refined by correlating to large amounts of statistical data in order to be a reasonable predictor of future behavior.

    The linked tool from jurassictest is very interesting, but there seems to be a lot of questionable assumptions used in the model. The noted Volt 16kW capacity certainly points to some inconsistency. Also inputting my 15 km (~9mi) commute at 100kph (~62mph) shows a calculated Wh/100km of 21.2 for the Leaf, and 18.15 for the Volt. That equates to 34.1kWh/100mi for the Leaf, and 29.2kWh/100mi for the Volt. The Leaf number almost exactly matches the EPA estimated 34kWh/mi, while the Volt's value is 19% better than the EPA estimated 36kWh/mi. Also interesting to note is that the EPA numbers are I believe AC kWh, while the simulator seems to be DC kWh as they are used to estimate range. So, interesting tool but I'm not sure the input data assumptions are good enough to make real comparisons. The model could certainly be refined, but we're back to needing a good set of statistical data to correlate it against and validate the input assumptions.

    I've also found this tool (EV Calculator) useful for estimating power requirements for different cruising speeds, but again its a big function of the variables you put into it. To the first order as long as the weight (including net of adding batteries/motor) matches the actual curb weight, tire resistance and Cd*area are right, and gear ratios are reasonable (at least for one gear), it should produce reasonable required HP values under drag calculations (which can be converted to kW). To get reasonable ranges out the battery, motor and inverter assumptions would also have to be reasonable. In general this method is probably more reasonable to use for relative comparisons (different speeds, inclines, maybe vehicles) than absolute values.

    I'd also be very interested to play with this tool (Main) that grew out of the old Prius Palm Simulator which seemed very well done. Haven't shelled out for it yet though.

    Rob
     
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  15. John H

    John H Senior Member

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    Thanks! It did seem really, really, really low. Are there any other benchmark tests, Europe perhaps, that show a pure EV range?
     
  16. miscrms

    miscrms Plug Envious Member

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    Here's one dataset on the Volt that looks pretty useful. This is data from a DOE monitored fleet of 150 Volts, driven 615,161 EV miles (~50% of total miles) from May 2011 to June 2012. They show an average 352 AC Wh per mile over that period/distance.

    Unfortunately they don't have an equivalent report on the Leaf or PiP for direct comparison.

    Sorry, forgot the link ;)
    http://204.134.140.90/pdf/EREV/GMMay11-June12.pdf
     
  17. drinnovation

    drinnovation EREV for EVER!

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    Interesint, but those are some very atypical drivers. They are only at 50% EV, so those drivers might by atypical in may other ways as well. If they have very long commutes, they may be driving at higher speeds for longer time periods and not care about efficency. Hard to comare that groupd to anyting.
     
  18. John H

    John H Senior Member

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    the more I revisit this, the more I want to gravitate toward a model that is weighted for the expected use of the vehicle, like we started to do with the OP. It seems that the expected daily drive route is a big component, the distance, the grade, the speeds of travel, the charging opportunities, etc ... the "driving style" does come into the equation but I'm not sure if it greatly affects the performance between vehicles types, i.e. a lead foot on the Prius vs a PiP, Ford HV, Leaf, or Volt.

    The OP may live uphill from their work place and be able to get 16 miles of EV going to work in either a PiP or a Volt. They travel back from work may be limited to under 45mpg, or an HOV sticker on one model might push them to 70mph.

    What would be a nice smart phone app would be a 30 day driving recorder that would use crowd sourced data to give a very accurate idea of how various vehicles would have performed over the same 30 days. i.e. you are driving a camry, and burned 42 gallons of gasoline in the last 30 days, in a Prius you would have burned 30 gallons, a PiP 15 gallons and 100kwh, a Leaf 0 gallons and 200kwh, a Volt 1 gallon and 180 kwh, etc ... (I just made up these comparison numbers, they are not based on ANYTHING)
     
  19. drinnovation

    drinnovation EREV for EVER!

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    lead foot on PiP vs Volt would definately make a difference on how much gas vs electric.

    There was a progrram called ecarapp that did some of what you ask.. it tracked your drive and used data from EV owners that had also tracked their drives to provide estimates. But I think the company died.
     
  20. john1701a

    john1701a Prius Guru

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    It's far more than even that. Daily usage varies dramatically. There is no realistic pattern to base estimates upon. Real-World needs & conditions change from day to day.

    I have collected over 3 years of daily data clearly showing that.
     
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