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Toyota Continues Open Technical Discussions on PHEV Designs

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  • Felix Kramer
    Irv Miller, Toyota s Group Vice President, Corporate Communications, continues to encourage broad discussions with the communities of PHEV and V2G advocates as
    Message 1 of 1 , Sep 25, 2007
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      Irv Miller, Toyota's Group Vice President,
      Corporate Communications, continues to encourage
      broad discussions with the communities of PHEV
      and V2G advocates as well as those interested in
      automotive engineering. Here Miller's reference
      to our responses prompted us and others to
      continue the discussion. Below is Miller's posting and our response.

      Toyota Open Road: September 24, 2007 06:56 AM
      IRV'S SHEET: Hybrid Tech: You Comment, We Respond
      http://blog.toyota.com/2007/09/irvs-sheet-hybr.html?cid=83928879

      Back on September 8th, I published a quick piece
      I called "Hybrid Tech: Parallel vs. Series." One
      of the great things about the blogosphere is that
      it's a two-way street, a format that invites, if
      you will, call and response, point and counterpoint.

      So it wasn't long until our friends at
      CalCars.org (or, more formally, California Cars
      Initiative for Plug-in Hybrids), to respond to my
      post with some interesting points. If you haven't
      already done so, you can read them by scrolling
      down to the comments section of my September 8 post.

      While we're pleased that the folks there are
      willing to engage in this important discussion,
      our general reaction to those comments is that
      unlike the Blue Ray-vs-HD/DVD metaphor that some
      have suggested, we don't see the
      series-vs-parallel discussion as an either/or
      sort of thing. We do not believe that only one
      solution will be adopted, and all others will be abandoned.

      Instead, what we expect is a diversity of
      solutions. That makes this a very exciting time
      for anyone who is interested in advancing
      automobile technology. Just as is the case with
      conventional internal-combustion engines, we
      expect to see many different approaches and nuances.

      In any case, it seems appropriate for me to
      clarify a few things, so here goes. . .

      First of all, it is asserted that existing Nickel
      Metal Hydride (NiMH) batteries similar to those
      used so successfully by Toyota's Hybrid Synergy
      Drive (HSD) system could drive the Chevrolet Volt
      (a hybrid prototype that was shown at the Detroit
      Show in January) 20 miles electrically without
      any change in the Volt's weight or other
      parameters ­ if they were designed for what's
      called deep discharge. Currently, with most NiMH
      batteries, deep discharge is problematic because
      the deeper the discharge, the shorter the battery
      life. And obviously longer life is preferable to shorter life.

      Anyway, the CalCars comments point out that that
      20-mile figure is double the 10-mile EV range
      that Volt prototypes reportedly will have ­ and
      importantly, they attribute that range claim to Toyota.

      First and foremost, that 10-mile range is not our
      claim. That was published in a story written by
      Jeff Green and Alan Ohnsman in Bloomberg.com on
      August 3, and published again on GM-Volt.com.
      That story cited unattributed information from
      inside General Motors saying that the Volt
      prototype will have a range of 10 miles. So that
      range figure appears to be right from the General's mouth.

      Just for the record, here, we have no idea what's
      going on inside General Motors, and further, have
      nothing to gain by downplaying their successes,
      and their advances, with hybrid technology. In
      point of fact, we wish them the best, because we
      believe that everybody benefits from hybrids, and
      from hybrid research and technology.

      With that being said, let us be sure that we all
      are talking with reference to the same set of
      definitions. Honda's hybrid, for instance, isn't
      a series hybrid system. It's a parallel hybrid
      system. Our Hybrid Synergy Drive system isn't a
      parallel hybrid system. It's a series/parallel
      hybrid system. The difference is the Honda system
      doesn't have an EV mode (series), but ours does.
      Likewise, the Volt doesn't have a traditional
      powertrain mode (parallel), but ours does.

      Now, here's the deal:

      Do we favor NiMH technology? Of course we do.
      Toyota is heavily invested in NiMH battery
      technology. In fact, we think we've probably
      produced more hybrids using NiMH batteries than
      all other manufactures combined.

      But because of our deep experience with NiMH
      technology, we also recognize the limits of these
      batteries with respect to cost, size, weight,
      recycling and life under wide state-of-charge
      swings. That is why we're developing new Lithium Ion technology.

      In theory, of course a series hybrid could be
      developed that pulled a 20- mile range from NiMH
      batteries. But it would have to be a
      purpose-built car that depended upon technology
      that's not applicable to other products.
      Meanwhile, Toyota's HSD can be applied, and is
      being applied, across our entire product range.

      But there's more that needs to be said about this
      business of battery-only driving range ­ and
      forgive me, here, but this will require some engineering talk.

      When range is discussed, it's important to also
      consider more than just the traction load. We
      also need to consider non-traction electric loads, AKA "hotel loads."

      In many, if not most cases, at low speeds, the
      "hotel load" (and for you non-technoids, "hotel
      load" basically means the power demand from
      devices that are necessary or that are demanded
      by consumers, but that are not part of the
      powertrain that propels the vehicle), can be
      higher than the traction load. And as the
      automobile becomes increasingly electrified
      (steer by wire, brake by wire, heat pumps, active
      suspension, etc.), the "hotel load" will require
      considerably more battery energy.

      Toyota thinks that it's important to let our
      customers know what they can realistically expect
      to experience in the future. Sure, it's possible
      for Car A to get a 20-mile electric range when
      driven at low speed with the air conditioning,
      lights and stereo turned off. But that obviously
      is not how the average person drives. When we
      factor in high-speed driving, use of the
      air-conditioning system, the audio system and so
      forth, Car A's actual all-electric range will be
      quite a bit less than that 20-mile grail.

      But what's more important here is that this
      discussion about the efficiency of one approach
      over another is, we believe, misplaced. What's
      important is not the specific efficiency of a
      battery vs. a transmission. What's important is
      the overall package, its acceptance by customers
      and the product's contribution to sustainable mobility.

      The market for vehicles in the U.S. is around 17
      million cars and trucks a year. In order to make
      a substantial reduction on our environmental
      footprint, the automobile industry needs products
      that can go to market today, be affordable, sell
      in large volumes, be easily serviceable and be
      capable of operating within the parameters of
      standard vehicle warranties. At Toyota, with
      Hybrid Synergy Drive, that's exactly what we're doing.

      [POSTS BY OTHER PEOPLE AT
      http://blog.toyota.com/2007/09/irvs-sheet-hybr.html?cid=83928879 ]

      CALCARS' RESPONSE

      We at CalCars.org are encouraged and energized by
      the continuing dialogue. We agree that everyone
      benefits by discussions of hybrid research and technology.

      We've asked Ron Gremban, our Technology Lead, to
      respond to some of the technical issues you just
      raised. (To keep it short, we don't address everything!)

      Ron wanted to be sure to start by saying that
      "since its introduction, I have been in awe of
      the engineering that went into the '04+ Prius and
      Toyota's Hybrid Synergy Drive." (And in his Sept
      13 response, he attributed the 10-mile Volt
      prototype range information to Toyota only
      because we hadn't seen the previous news reports
      on which the comment was based.) Ron continues:

      I agree wholeheartedly that series, parallel, and
      series/parallel hybrids and PHEVs will co-exist
      for some time in the marketplace, if not from now
      on. No single configuration has all the advantages.

      Part of Toyota's strong experience with NiMH
      batteries comes from the deep-discharge
      1990s-technology NiMH packs used in Toyota's RAV4
      EVs, some of which by now have well over 100,000
      miles on them without significant battery
      degradation. In fact, the Electric Power Research
      Institute (EPRI)'s prediction that NiMH and
      Li-ion batteries can both last the life of a PHEV
      is based on that field data as well as its
      PHEV-specific laboratory testing. Yes, cycle life
      of any battery is reduced with deeper discharge.
      This merely means that the engineering tradeoffs
      between pack size, depth of discharge, cycle
      life, power handling capabilities, etc. must be
      chosen carefully, using both engineering and economic expertise.

      "Hotel loads" must be supplied, if not from a
      battery, from gasoline at the internal combustion
      engine (ICE)'s same 15-35% efficiency as
      available to propel the vehicle. Therefore, all
      the advantages of using grid electricity to
      propel the vehicle apply equally to using grid
      electricity to supply hotel loads. Even when this
      energy provides less EV range in cold or hot
      weather use, it is still displacing the same
      amount of gasoline (or more, since electric A/C
      compressors are far more efficient than
      engine-driven ones). The one exception is cabin
      heating, which is normally supplied from ICE
      waste heat. When it is too cold for an air
      conditioning heat pump to efficiently heat the
      cabin, EV purity can be sacrificed (independent
      of hybrid type) by running the ICE occasionally
      to build up sufficient waste heat for cabin
      heating. ICEs produce so much waste heat that
      mere occasional operation will be quite sufficient.

      Plus a final note from Felix Kramer, returning to
      a less technical perspective: We agree with Irv
      Miller's description of the attributes of cars
      that can sell in the millions. But we suggest a
      way to get there most rapidly, reflecting the
      urgency of climate crisis and fossil fuel
      dependency, is by producing (and selling in
      surprisingly substantial numbers) "good enough to
      start Version 1.0" PHEVs from which automakers
      will all learn. Remember the first cellphones:
      brick-sized and costing in the thousands? We're
      glad the manufacturers started producing them to
      continue improving them while scaling up production.

      -- Felix Kramer, Founder, The California Cars Initiative 05:45 PM
      You can also find comments (some of which overlap
      with ones at Open Road blog, and some of which aren't all that polite!) at
      http://www.autobloggreen.com/2007/09/24/toyotas-irv-miller-jumps-into-series-parallel-debate-again-now

      -- -- -- -- -- -- -- -- -- -- -- --
      Felix Kramer fkramer@...
      Founder California Cars Initiative
      http://www.calcars.org
      http://www.calcars.org/news-archive.html
      -- -- -- -- -- -- -- -- -- -- -- --
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