The Prius learns some new “PHEV” tricks

Discussion in 'PHEV or Plug-in Hybrid Electric Vehicle' started by Right Lane Cruiser, Jun 12, 2009.

  1. jimepting

    jimepting Well-Known Member

    I agree that a comprehensive measure would be very, very complex. And, there are all sorts of social/environmental issues that get raised. For example, it is vastly more enviormentally conscious to use electricity from wind/hydro than from coal to power a car. The social/environmental question would not even be addressed by the sort of "equivalent" fuel consumption calculations that I suggested. To try this would be to open a "Pandor's Box." As an example of a social question raised, similar to the food to fuel criticism of ethanol, would be the question of driving up poor folks electric bills and putting lighting/heating in competition with transportation fuels.

    I'm suggesting some questions. Taking the coward's way out, I certainly don't intend to resolve any of them. I have more interesting things to do;) I do know one thing for sure, with little or no study, there is no free lunch.

    Powering a car with American generated electricity does sound pretty good so long as there isn't a long resulting co2 tail, but increasingly our electricity comes from coal :(
    Last edited: Jun 13, 2009
  2. lightfoot

    lightfoot Reformed speeder

    It doesn't have to be complex. You fill up the gas, charge the battery, drive some standard route/cycle, then top off the tank and charge the battery to the same SOC, and thus measure how many gallons and how many kilowatt hours were needed to travel that route.

    When someone says "this plug-in gets 170 mpg", what is missing is the second source of energy (electricity) that was used. We're used to variations in mpg due to driver, route(s), weather, vehicle condition and setup, etc. But "mpg" for plug-ins would vary far more once the battery is depleted and the ICE must be used.

    Taliesin, by "meaningless" I didn't mean that mpg is unimportant, I meant that plugin claims have no validity in comparing the efficiency of vehicles UNLESS electrical usage is factored in somehow..

    For gasoline, we do not factor in the environmental, social, and (huge) political costs associated with a gallon of gasoline at the pump. These are horrifying to contemplate, but, as for electricity, they would be very difficult to calculate with precision. So number-wise it makes sense to just look at the energy (electricity, gas) flowing into the vehicle.

    STM that we were at a similar point when the EPA estimates were introduced. Mfrs were making wild claims of the fuel efficiency of their vehicles, so the gov't stepped in to provide standardized comparisons. Of course, this backfired because people now assume that no matter what they do with the gas pedal, the vehicle will "get" roughly the EPA rating. I know I did before I found this site.
    Last edited: Jun 13, 2009
  3. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi Marc:

    ___I was fortunate enough to speak with the actual Japanese engineer that spec'ed MG1 on both the Prius-II and the -III. 10,000 RPM is a very conservative spec. 15,000 R's would not be out of line as long as it was done for a short period of time. In other words, let her rip for three or four minutes and no harm will come of it. Three or four minutes a day 5-days a week, there could be long term issues.

    ___Regarding Toyota's OEM PHEV, the ICE is not spinning up through 62 mph. A huge savings in terms of kWh by not having to artificially spin up the ICE from 41 through 62 mph. I could live with 62 mph anywhere on the planet and go to Warp Neutral for the downhill sections in the mountains ;)

    ___John, for sure there has to be an accounting for the plug power but as far as CO2 emissions from a coal plant powering a PHEV, it is less than burning gasoline to cover the same distance. In IL., these guys are powered by 70% nuclear.

    ___Electricity to the highest bidder due to an overloaded grid? That one could be a problem but we will probably not see it for at least another 7 to 10-years. Soon after it becomes a problem, there are a lot of film based solar plants ready to ramp up to fill the needs of you, I and everyone else. I hope???

    ___Good Luck

    Last edited: Jun 13, 2009
  4. hobbit

    hobbit He who posts articles

    I have to call at least partial BS on this. First of all, the
    Prius does not have a temperature probe on either catalytic
    converter; that figure is a guesstimate that the ECU makes based
    on various runtime conditions and is NOT the actual temperature
    of anything. Second, at no point in their camera-technique-
    challenged video do they ever show engine RPM, which would be
    a much better indicator of what's going on. Whether it's injecting
    or not is another matter, but I want to know exactly what happened
    at the 42 mph boundary as far as bringing it into spinning or
    not. And third, not even a mention of inverter temps, which
    they didn't seem to be monitoring, and of course nobody would
    think to reach a hand in to the battery-box area or behind
    the inverter to feel how hot any of the wiring was getting.
    You run 100 amps through that system for more than a couple of
    minutes, you *are* going to start seeing some issues.
    There's also no confirmation of whether they're changing *Toyota's*
    firmware in any of the ECUs or just hacking around it more
    creatively with their own. I would guess the latter, as usual.
    Note that you cannot see over the MFD hump to where the
    "check engine" light would be showing if it was on??
    Conclusion: rigged demo, with a lot hidden behind the curtain and
    some nice potential but not at the levels they're claiming. Cannot
    accept otherwise without having a *lot* more information first,
    especially when thinking about long-term effects on the car.
    I'm going to single-frame through some more of the video to see
    if I can spot any better indicators.
  5. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi Al:

    ___I would not call it BS but I would call it some sharp hacking at the expense of Toyota's bulletproof reliability.

    ___I am trying to get a hold of these guys for a ride myself and if the OBD-II port is still open, at least we can see what is going on. I suspect they only hacked the injector shutdown and not the ICE above 41 mph thus its simple WS with a 25 kW hour kick unlike the other PHEV conversions w/ a 7kW punch. Poor inverter/transverter, MG1 and MG2 ;)

    ___Good Luck

  6. hobbit

    hobbit He who posts articles

    Yep ... while a few folks have managed to burn MG2 windings in
    the Classic prius, I don't think anyone's managed to do it in
    the 2nd-gen yet ... these fellas might be the first! Well,
    whatever additional running-state info you can obtain would
    be really useful...
  7. cuchulain

    cuchulain He who posts articles

    Unfortunately with the Google Recharge IT Hymotion Prius if we use the worst case coal analogy i.e. Equivalent CO2 at 14.4kWh per gallon of gasoline. (

    They get blended MPG of 55.4mpg and a blended electricity of 131.5Wh/mile.Converting the electricity component to gasoline. This calculates to a CO2 equivalent MPG 36.8mpg which is more CO2 than their non converted Prius fleet at 42.8mpg. Although for them they use PV panels so they probably do not mind that their electricity is been frittered away.

    If we use the MPG of the non converted Prius fleet at 42.8mpg we can calculate, the actual electrical efficiency as 578Wh/mile, almost twice Jays efficiency of 287Wh/mile. It is hard to believe this figure, If we use Jays efficiency of 287Wh/mile then the real mpg in gasoline 30mpg.

    There is a second video here

    Good Luck
  8. hobbit

    hobbit He who posts articles

    I've consolidated some thoughts on the high-speed Prius EV thing
    in a long-overdue page about my fuel cut switch which can also
    create some of the same unusual conditions that some of the PHEV
    folks are exploiting. Except that some of them cause it faster
    by breaking the 12V supply to the engine ECU instead.

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