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Re: When do you use N, as opposed to D or B?

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  • Steve Schrier
    The only time I ve used the N gear is when going through a car wash system. After removing the radio antenna and shifting into N the touchscreen comes on
    Message 1 of 25 , Oct 1, 2000
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      The only time I've used the "N" gear is when going through a car wash
      system. After removing the radio antenna and shifting into "N" the
      touchscreen comes on with a reminder not to leave the car in "N" for
      extended time. For the car wash it's all ok in "N".


      -- In toyota-prius@egroups.com, wtilley@e... wrote
      > Does anyone have any idea when using N is appropriate in the Prius?
      > I've read the posts regarding use of D and B. This question is
      asked
      > from the perspective of someone who normally drives with a standard
      > transmission (Geo Metro XFi) and kicks out of gear when going down
      > hill to allow the engine to idle and thus increase fuel
      > economy/reduce engine wear. Curious what effect this same approach
      > might have in the Prius (assuming you weren't in need of some
      serious
      > battery recharging; then I assume B would be the appropriate
      choice).
    • Christopher Culp
      Too bad you couldn t put it in B when being towed ...to get a charge from the tow-truck? HA! Got mine Saturday. (Lovely lite-blue ice-type color.) Getting
      Message 2 of 25 , Oct 2, 2000
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        Too bad you couldn't put it in B when being towed ...to get a charge
        from
        the tow-truck?

        HA!

        'Got mine Saturday. (Lovely lite-blue ice-type color.) Getting about
        45mpg
        on the way to work (average speed 30mph stop/go). One 5min slice got up
        to 75mpg
        but...we'll see how it goes from here.

        pax

        c.culp


        louisd@... wrote:
        >
        > The answer is there's almost never a case to use N on the Prius. The
        > N position prevents electricity from being generated and would
        > decrease your mileage by forcing the ICE to come on later to generate
        > the power you could have captured coasting/braking.
        >
        > The book seems to indicate that the ONLY time to use "N" is when the
        > car is being towed.
        >
        > Here's what the book says: "With the selector in "N" position, the
        > hybrid vehicle battery will not be charged even if the gasoline
        > engine operates. You cannot start your vehicle if the selector lever
        > is left in "N" position for a long time because the hybrid battery
        > will discharge."
        >
        > --Louis
        >
        > --- In toyota-prius@egroups.com, wtilley@e... wrote:
        > > Does anyone have any idea when using N is appropriate in the Prius?
        > > I've read the posts regarding use of D and B. This question is
        > asked
        > > from the perspective of someone who normally drives with a standard
        > > transmission (Geo Metro XFi) and kicks out of gear when going down
        > > hill to allow the engine to idle and thus increase fuel
        > > economy/reduce engine wear. Curious what effect this same approach
        > > might have in the Prius (assuming you weren't in need of some
        > serious
        > > battery recharging; then I assume B would be the appropriate
        > choice).
        >
        > To unsubscribe from this group, send an email to:
        > toyota-prius-unsubscribe@egroups.com
      • Lee Hart
        ... We ve had our Prius for about 1000 miles so far. I can tell you subjectively what driving in D, B, and N feels like. In D, it drives like any car with an
        Message 3 of 25 , Oct 2, 2000
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          wtilley@... wrote:
          > Does anyone have any idea when using N is appropriate in the Prius?

          We've had our Prius for about 1000 miles so far. I can tell you
          subjectively what driving in D, B, and N feels like.

          In D, it drives like any car with an automatic transmission in D. It
          creeps ahead if you take your foot off the brake from a dead stop. If
          you take your foot off the accellerator, there is mild engine braking,
          and the dash display indicates it is recharging the battery.

          If you downshift to B, gas mileage is a little worse, and the engine
          seems to rev up a little higher when just driving around. The car does
          not accellerate any faster, and seems to have the same top speed (though
          I haven't tried B on an expressway). When you take your foot off the
          accellerator in B, there is strong engine braking. You generally won't
          need the brakes at all to slow down until the speed is under 20 mph or
          so. The display indicates that it is recharging the battery, but no more
          energy is recovered that it would have been in D. This makes sense; a
          car rolling at X mph has a fixed amount of kinetic energy, so the same
          amount is available to be recovered whether you stop quickly or slowly.

          If you shift into N, the car coasts. No energy is recovered, and the
          battery is not charged.
          --
          Lee A. Hart Ring the bells that still can ring
          814 8th Ave. N. Forget your perfect offering
          Sartell, MN 56377 USA There is a crack in everything
          leeahart_at_earthlink.net That's how the light gets in - Leonard Cohen
        • Lee Hart
          ... As a long-time driver of electric vehicles, I can tell you that this isn t quite true. You will get the greatest range and efficiency (regardless of
          Message 4 of 25 , Oct 2, 2000
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            louisd@... wrote:
            > The N position prevents electricity from being generated and would
            > decrease your mileage by forcing the ICE to come on later to generate
            > the power you could have captured coasting/braking.

            As a long-time driver of electric vehicles, I can tell you that this
            isn't quite true. You will get the greatest range and efficiency
            (regardless of whether you have regenerative braking or not) by NOT
            using the brakes (regular OR regenerative).

            If you stay in D, and use "engine braking" (regenerative braking) to
            slow down, then you will only get back a portion of the power that went
            into accellerating the car. Given the efficiency of the generator,
            motor, controller, and batteries, you only get back about 50% of the
            power it took to accellerate. The other 50% repressents an unrecovered
            loss.

            Shifting to N lets the car coast. This means it is using as close to
            zero power as possible. Maximum economy is achieved by using whatever
            engine power is needed to accellerate or maintain speed, and then
            letting it coast down to a stop in N.

            For example, if you used regenerative braking in D to stop in 1 mile,
            you recovered enough energy to drive 1/2 mile. But if you coasted in N,
            the car would have gone 2 miles. So you get farther in N for the same
            amount of fuel, thus higher gas mileage.

            But what does this mean from a practical point of view? Traffic, road
            conditions, and your own impatience almost never let you coast for any
            length of time. The car would go too slow, or too fast, or take too long
            to coast to a stop. So sure, you can improve gas mileage a little, but
            no one will do it except to win a bet or contest.

            So practically speaking, you would never use N unless you are going down
            a long, slight hill such that you maintain a reasonable speed without
            any engine or braking.
            --
            Lee A. Hart Ring the bells that still can ring
            814 8th Ave. N. Forget your perfect offering
            Sartell, MN 56377 USA There is a crack in everything
            leeahart_at_earthlink.net That's how the light gets in - Leonard Cohen
          • Eric Zeller
            On Sun, 1 Oct 2000, Doug Pratt wrote: my guess is N is used by service people to have the engine running while they are working on it. (My first car had a
            Message 5 of 25 , Oct 2, 2000
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              On Sun, 1 Oct 2000, Doug Pratt wrote:

              my guess is N is used by service people to have the engine running while
              they are working on it. (My first car had a variomatic transmission and
              the manual cleary stated many times over and over again do not use N
              except for servicing the car, and in fact shifting from N into gear while
              the engine was running could severely damage the transmission).
              The cool thing about that car was that it could as fast in reverse as it
              could forward (which wasn't very fast).


              > The Prius does you even better than kicking your manual into neutral when
              > going downhill. When you're going downhill and there's no call for power,
              > it turns the engine OFF! I live in hilly Northern California and have often
              > been going downhill in excess of 50 or 60 mph with the engine off. I would
              > definately not recommend trying to second guess the control system by
              > shifting into N. It's smarter and faster than you are, and many automatic
              > transmissions can be damaged by shifting into N at higher speeds.
              > There's no real use for N, except as a traditional spacer between D and R.
              >
              > -Doug Pratt
              >
              > wtilley@... wrote:
              >
              > > Does anyone have any idea when using N is appropriate in the Prius?
              > > I've read the posts regarding use of D and B. This question is asked
              > > from the perspective of someone who normally drives with a standard
              > > transmission (Geo Metro XFi) and kicks out of gear when going down
              > > hill to allow the engine to idle and thus increase fuel
              > > economy/reduce engine wear. Curious what effect this same approach
              > > might have in the Prius (assuming you weren't in need of some serious
              > > battery recharging; then I assume B would be the appropriate choice).
              > >
              >
              >
              > To unsubscribe from this group, send an email to:
              > toyota-prius-unsubscribe@egroups.com
              >
              >
              >
              >

              --
              Eric Zeller A disgruntled Oacis employee ezeller@...
              http://www.ericzeller.com
              "The Ships hung in the air in exactly the same way bricks don't" - HHGTTG
            • S. B.
              Hello, I m having a difficult time figuring out the B gear. From what I m reading, the B gear allows for faster recharging, but in less time. However the
              Message 6 of 25 , Oct 2, 2000
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                Hello,
                I'm having a difficult time figuring out the "B" gear. From what I'm
                reading, the "B" gear allows for faster recharging, but in less time.
                However the same amount of energy is recovered as in the "D" gear
                using just regen, except in a shorter distance? Example: Say I'm
                going downhill, but the regen does not have enough force to bring
                down
                the car's momentum and so it still speeds up, but I decide to use it
                anyways and let's say it gets 7 units of electricity (for example)
                until I reach down to 50 mph after the downhill grade. Instead of
                the
                "D" gear, I then select the "B" gear and more quickly reach 50 mph;
                will I get 7 units of energy, in less space? Or this may be the
                better question to ask: Will using the "B" gear recharge the
                batteries faster than in the "D" gear? Thanks.

                --- In toyota-prius@egroups.com, Lee Hart <leeahart@e...> wrote:
                > wtilley@e... wrote:
                > > Does anyone have any idea when using N is appropriate in the
                Prius?
                >
                > We've had our Prius for about 1000 miles so far. I can tell you
                > subjectively what driving in D, B, and N feels like.
                >
                > In D, it drives like any car with an automatic transmission in D. It
                > creeps ahead if you take your foot off the brake from a dead stop.
                If
                > you take your foot off the accellerator, there is mild engine
                braking,
                > and the dash display indicates it is recharging the battery.
                >
                > If you downshift to B, gas mileage is a little worse, and the engine
                > seems to rev up a little higher when just driving around. The car
                does
                > not accellerate any faster, and seems to have the same top speed
                (though
                > I haven't tried B on an expressway). When you take your foot off the
                > accellerator in B, there is strong engine braking. You generally
                won't
                > need the brakes at all to slow down until the speed is under 20 mph
                or
                > so. The display indicates that it is recharging the battery, but no
                more
                > energy is recovered that it would have been in D. This makes sense;
                a
                > car rolling at X mph has a fixed amount of kinetic energy, so the
                same
                > amount is available to be recovered whether you stop quickly or
                slowly.
                >
                > If you shift into N, the car coasts. No energy is recovered, and the
                > battery is not charged.
                > --
                > Lee A. Hart Ring the bells that still can ring
                > 814 8th Ave. N. Forget your perfect offering
                > Sartell, MN 56377 USA There is a crack in everything
                > leeahart_at_earthlink.net That's how the light gets in - Leonard
                Cohen
              • S. B.
                OK, now that I think of it, I have found the correct question to ask. I understand that the net electricity captured from D or B will be the same (unless
                Message 7 of 25 , Oct 2, 2000
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                  OK, now that I think of it, I have found the correct question to ask.
                  I understand that the net electricity captured from "D" or "B" will
                  be the same (unless conditions prove otherwise, like having to stop
                  more quickly and use the brakes or something like that). But, will
                  using the "B" gear get to that net electricity value more quickly
                  than
                  in the "D" gear going from one speed to a slower speed or to a stop?

                  --- In toyota-prius@egroups.com, "S. B." <altopsionic@n...> wrote:
                  > Hello,
                  > I'm having a difficult time figuring out the "B" gear. From what
                  I'm
                  > reading, the "B" gear allows for faster recharging, but in less
                  time.
                  > However the same amount of energy is recovered as in the "D" gear
                  > using just regen, except in a shorter distance? Example: Say I'm
                  > going downhill, but the regen does not have enough force to bring
                  > down
                  > the car's momentum and so it still speeds up, but I decide to use
                  it
                  > anyways and let's say it gets 7 units of electricity (for example)
                  > until I reach down to 50 mph after the downhill grade. Instead of
                  > the
                  > "D" gear, I then select the "B" gear and more quickly reach 50 mph;
                  > will I get 7 units of energy, in less space? Or this may be the
                  > better question to ask: Will using the "B" gear recharge the
                  > batteries faster than in the "D" gear? Thanks.
                  >
                  > --- In toyota-prius@egroups.com, Lee Hart <leeahart@e...> wrote:
                  > > wtilley@e... wrote:
                  > > > Does anyone have any idea when using N is appropriate in the
                  > Prius?
                  > >
                  > > We've had our Prius for about 1000 miles so far. I can tell you
                  > > subjectively what driving in D, B, and N feels like.
                  > >
                  > > In D, it drives like any car with an automatic transmission in D.
                  It
                  > > creeps ahead if you take your foot off the brake from a dead
                  stop.
                  > If
                  > > you take your foot off the accellerator, there is mild engine
                  > braking,
                  > > and the dash display indicates it is recharging the battery.
                  > >
                  > > If you downshift to B, gas mileage is a little worse, and the
                  engine
                  > > seems to rev up a little higher when just driving around. The car
                  > does
                  > > not accellerate any faster, and seems to have the same top speed
                  > (though
                  > > I haven't tried B on an expressway). When you take your foot off
                  the
                  > > accellerator in B, there is strong engine braking. You generally
                  > won't
                  > > need the brakes at all to slow down until the speed is under 20
                  mph
                  > or
                  > > so. The display indicates that it is recharging the battery, but
                  no
                  > more
                  > > energy is recovered that it would have been in D. This makes
                  sense;
                  > a
                  > > car rolling at X mph has a fixed amount of kinetic energy, so the
                  > same
                  > > amount is available to be recovered whether you stop quickly or
                  > slowly.
                  > >
                  > > If you shift into N, the car coasts. No energy is recovered, and
                  the
                  > > battery is not charged.
                  > > --
                  > > Lee A. Hart Ring the bells that still can ring
                  > > 814 8th Ave. N. Forget your perfect offering
                  > > Sartell, MN 56377 USA There is a crack in everything
                  > > leeahart_at_earthlink.net That's how the light gets in - Leonard
                  > Cohen
                • Christopher Culp
                  Just conjecture on my part, but since the slowing down is quicker in the B mode, this implies more work is being put into the generator, which should equate
                  Message 8 of 25 , Oct 2, 2000
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                    Just conjecture on my part, but since the slowing down is quicker in the
                    B
                    mode, this implies more "work" is being put into the generator, which
                    should
                    equate to more volts/amps. So you slow down faster and should, I would
                    think,
                    get more results than in D mode for the same "coasting" mode.

                    pax

                    c.culp


                    "S. B." wrote:
                    >
                    > OK, now that I think of it, I have found the correct question to ask.
                    > I understand that the net electricity captured from "D" or "B" will
                    > be the same (unless conditions prove otherwise, like having to stop
                    > more quickly and use the brakes or something like that). But, will
                    > using the "B" gear get to that net electricity value more quickly
                    > than
                    > in the "D" gear going from one speed to a slower speed or to a stop?
                    >
                    > --- In toyota-prius@egroups.com, "S. B." <altopsionic@n...> wrote:
                    > > Hello,
                    > > I'm having a difficult time figuring out the "B" gear. From what
                    > I'm
                    > > reading, the "B" gear allows for faster recharging, but in less
                    > time.
                    > > However the same amount of energy is recovered as in the "D" gear
                    > > using just regen, except in a shorter distance? Example: Say I'm
                    > > going downhill, but the regen does not have enough force to bring
                    > > down
                    > > the car's momentum and so it still speeds up, but I decide to use
                    > it
                    > > anyways and let's say it gets 7 units of electricity (for example)
                    > > until I reach down to 50 mph after the downhill grade. Instead of
                    > > the
                    > > "D" gear, I then select the "B" gear and more quickly reach 50 mph;
                    > > will I get 7 units of energy, in less space? Or this may be the
                    > > better question to ask: Will using the "B" gear recharge the
                    > > batteries faster than in the "D" gear? Thanks.
                    > >
                    > > --- In toyota-prius@egroups.com, Lee Hart <leeahart@e...> wrote:
                    > > > wtilley@e... wrote:
                    > > > > Does anyone have any idea when using N is appropriate in the
                    > > Prius?
                    > > >
                    > > > We've had our Prius for about 1000 miles so far. I can tell you
                    > > > subjectively what driving in D, B, and N feels like.
                    > > >
                    > > > In D, it drives like any car with an automatic transmission in D.
                    > It
                    > > > creeps ahead if you take your foot off the brake from a dead
                    > stop.
                    > > If
                    > > > you take your foot off the accellerator, there is mild engine
                    > > braking,
                    > > > and the dash display indicates it is recharging the battery.
                    > > >
                    > > > If you downshift to B, gas mileage is a little worse, and the
                    > engine
                    > > > seems to rev up a little higher when just driving around. The car
                    > > does
                    > > > not accellerate any faster, and seems to have the same top speed
                    > > (though
                    > > > I haven't tried B on an expressway). When you take your foot off
                    > the
                    > > > accellerator in B, there is strong engine braking. You generally
                    > > won't
                    > > > need the brakes at all to slow down until the speed is under 20
                    > mph
                    > > or
                    > > > so. The display indicates that it is recharging the battery, but
                    > no
                    > > more
                    > > > energy is recovered that it would have been in D. This makes
                    > sense;
                    > > a
                    > > > car rolling at X mph has a fixed amount of kinetic energy, so the
                    > > same
                    > > > amount is available to be recovered whether you stop quickly or
                    > > slowly.
                    > > >
                    > > > If you shift into N, the car coasts. No energy is recovered, and
                    > the
                    > > > battery is not charged.
                    > > > --
                    > > > Lee A. Hart Ring the bells that still can ring
                    > > > 814 8th Ave. N. Forget your perfect offering
                    > > > Sartell, MN 56377 USA There is a crack in everything
                    > > > leeahart_at_earthlink.net That's how the light gets in - Leonard
                    > > Cohen
                    >
                    > To unsubscribe from this group, send an email to:
                    > toyota-prius-unsubscribe@egroups.com
                  • bfroelich@easent.com
                    Yes, I think you are right. But B is mainly for going down hills. When you go down a hill, you use a combination of regeneration and brakes to maintain
                    Message 9 of 25 , Oct 2, 2000
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                      Yes, I think you are right. But B is mainly for going down hills.
                      When you go down a hill, you use a combination of regeneration and
                      brakes to maintain constant speed. B shifts the balance toward
                      regeneration, so that at the bottom of the hill you will have
                      recovered more energy to the battery than if you were in D. Note
                      that the energy you recover is part of what you previously expended
                      in fighting gravity to climb the hill.

                      D is for normal cruising, where you prefer to let the car coast along
                      at constant speed. So D puts less emphasis on regeneration.

                      If you cruise in B, you are "threshing" the system. The car does
                      more regeneration, which slows it down, which causes you to step
                      harder on the gas. You are not recovering energy from gravity, as in
                      the case of a downhill, rather you are circulating energy into the
                      battery and out again through the electric motor. The generator and
                      motor are not perfect, so you lose some energy in this process, and
                      MPG suffers.

                      Don't take this as gospel; it's just my inference from reading about
                      the Prius and driving it.


                      --- In toyota-prius@egroups.com, "S. B." <altopsionic@n...> wrote:
                      > OK, now that I think of it, I have found the correct question to
                      ask.
                      > I understand that the net electricity captured from "D" or "B"
                      will
                      > be the same (unless conditions prove otherwise, like having to stop
                      > more quickly and use the brakes or something like that). But, will
                      > using the "B" gear get to that net electricity value more quickly
                      > than
                      > in the "D" gear going from one speed to a slower speed or to a stop?
                      >
                    • S. B.
                      Thanks for the info! Now I finally understand the B gear concept. ... along ... in ... and ... about ... stop ... will ... stop?
                      Message 10 of 25 , Oct 2, 2000
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                        Thanks for the info! Now I finally understand the "B" gear concept.

                        --- In toyota-prius@egroups.com, bfroelich@e... wrote:
                        > Yes, I think you are right. But B is mainly for going down hills.
                        > When you go down a hill, you use a combination of regeneration and
                        > brakes to maintain constant speed. B shifts the balance toward
                        > regeneration, so that at the bottom of the hill you will have
                        > recovered more energy to the battery than if you were in D. Note
                        > that the energy you recover is part of what you previously expended
                        > in fighting gravity to climb the hill.
                        >
                        > D is for normal cruising, where you prefer to let the car coast
                        along
                        > at constant speed. So D puts less emphasis on regeneration.
                        >
                        > If you cruise in B, you are "threshing" the system. The car does
                        > more regeneration, which slows it down, which causes you to step
                        > harder on the gas. You are not recovering energy from gravity, as
                        in
                        > the case of a downhill, rather you are circulating energy into the
                        > battery and out again through the electric motor. The generator
                        and
                        > motor are not perfect, so you lose some energy in this process, and
                        > MPG suffers.
                        >
                        > Don't take this as gospel; it's just my inference from reading
                        about
                        > the Prius and driving it.
                        >
                        >
                        > --- In toyota-prius@egroups.com, "S. B." <altopsionic@n...> wrote:
                        > > OK, now that I think of it, I have found the correct question to
                        > ask.
                        > > I understand that the net electricity captured from "D" or "B"
                        > will
                        > > be the same (unless conditions prove otherwise, like having to
                        stop
                        > > more quickly and use the brakes or something like that). But,
                        will
                        > > using the "B" gear get to that net electricity value more quickly
                        > > than
                        > > in the "D" gear going from one speed to a slower speed or to a
                        stop?
                        > >
                      • RobertSnyder@worldnet.att.net
                        ... I like it!!!! You have an evil mind c. ... Congratulations!!!! You ll have lots of fun with it. Good job on the mileage.
                        Message 11 of 25 , Oct 2, 2000
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                          --- In toyota-prius@egroups.com, Christopher Culp <culp@e...> wrote:
                          > Too bad you couldn't put it in B when being towed ...to get a charge
                          > from the tow-truck?
                          >
                          > HA!

                          I like it!!!! You have an evil mind c.


                          >
                          > 'Got mine Saturday. (Lovely lite-blue ice-type color.) Getting
                          > about 45mpg
                          > on the way to work (average speed 30mph stop/go). One 5min slice
                          > got up to 75mpg but...we'll see how it goes from here.
                          >
                          > pax
                          >
                          > c.culp

                          Congratulations!!!! You'll have lots of fun with it. Good job on
                          the mileage.
                        • bfroelich@easent.com
                          Interesting! I would have guessed that you d recover more energy in B than in D, not the same amount. This pretty much blows what I said in #1724 out of the
                          Message 12 of 25 , Oct 3, 2000
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                            Interesting! I would have guessed that you'd recover more energy in
                            B than in D, not the same amount. This pretty much blows what I said
                            in #1724 out of the water. Glad to have some real-world data to set
                            me straight.

                            --- In toyota-prius@egroups.com, Lee Hart <leeahart@e...> wrote:
                            >
                            > I can only tell you what seems to be happening, based on my own
                            limited
                            > experience with our Prius.
                            >
                            > We live at the top of a long hill. If I coast down the hill from
                            top
                            to
                            > bottom in D, I recover 1.5 "E"'s worth of energy (according to the
                            dash
                            > display, where each "E" is 50 watt-hours of recovered energy).
                            >
                            > But there is a 20 mph speed limit on that hill when school is open.
                            The
                            > car coasts too fast in D. If I put it in B, it now coasts down the
                            hill
                            > and stays below 20 mph. At the bottom, I still have 1.5 "E"'s worth
                            of
                            > energy.
                            >
                            > So using B recovers the same amount of energy as D, but keeps your
                            speed
                            > slower on hills, or brings your speed down faster on flat ground.
                            > --
                            > Lee A. Hart Ring the bells that still can ring
                            > 814 8th Ave. N. Forget your perfect offering
                            > Sartell, MN 56377 USA There is a crack in everything
                            > leeahart_at_earthlink.net That's how the light gets in - Leonard
                            Cohen
                          • Lee Hart
                            ... I can only tell you what seems to be happening, based on my own limited experience with our Prius. We live at the top of a long hill. If I coast down the
                            Message 13 of 25 , Oct 3, 2000
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                              S. B. wrote:
                              > From what I'm reading, the "B" gear allows for faster recharging, but
                              > in less time. However the same amount of energy is recovered as in the
                              > "D" gear using just regen, except in a shorter distance? Example: Say
                              > I'm going downhill, but the regen does not have enough force to bring
                              > down the car's momentum and so it still speeds up, but I decide to use
                              > it anyways and let's say it gets 7 units of electricity (for example)
                              > until I reach down to 50 mph after the downhill grade. Instead of the
                              > "D" gear, I then select the "B" gear and more quickly reach 50 mph;
                              > will I get 7 units of energy, in less space? Or this may be the
                              > better question to ask: Will using the "B" gear recharge the
                              > batteries faster than in the "D" gear?

                              I can only tell you what seems to be happening, based on my own limited
                              experience with our Prius.

                              We live at the top of a long hill. If I coast down the hill from top to
                              bottom in D, I recover 1.5 "E"'s worth of energy (according to the dash
                              display, where each "E" is 50 watt-hours of recovered energy).

                              But there is a 20 mph speed limit on that hill when school is open. The
                              car coasts too fast in D. If I put it in B, it now coasts down the hill
                              and stays below 20 mph. At the bottom, I still have 1.5 "E"'s worth of
                              energy.

                              So using B recovers the same amount of energy as D, but keeps your speed
                              slower on hills, or brings your speed down faster on flat ground.
                              --
                              Lee A. Hart Ring the bells that still can ring
                              814 8th Ave. N. Forget your perfect offering
                              Sartell, MN 56377 USA There is a crack in everything
                              leeahart_at_earthlink.net That's how the light gets in - Leonard Cohen
                            • Williams, Sam
                              This is good information, and confirms what ee_of_ee said, that it doesn t make any difference . I m glad that s the case because it eliminates any
                              Message 14 of 25 , Oct 3, 2000
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                                This is good information, and confirms what "ee_of_ee" said, that "it
                                doesn't make any difference". I'm glad that's the case because it
                                eliminates any temptation to shift to "B" to improve energy recovery.

                                Sam Williams

                                > -----Original Message-----
                                > From: Lee Hart [SMTP:leeahart@...]
                                > Sent: Tuesday, October 03, 2000 5:01 PM
                                > To: toyota-prius@egroups.com
                                > Subject: Re: [toyota-prius] Re: When do you use N, as opposed to D or
                                > B?
                                >
                                >
                                > I can only tell you what seems to be happening, based on my own limited
                                > experience with our Prius.
                                >
                                > We live at the top of a long hill. If I coast down the hill from top to
                                > bottom in D, I recover 1.5 "E"'s worth of energy (according to the dash
                                > display, where each "E" is 50 watt-hours of recovered energy).
                                >
                                > But there is a 20 mph speed limit on that hill when school is open. The
                                > car coasts too fast in D. If I put it in B, it now coasts down the hill
                                > and stays below 20 mph. At the bottom, I still have 1.5 "E"'s worth of
                                > energy.
                                >
                                > So using B recovers the same amount of energy as D, but keeps your speed
                                > slower on hills, or brings your speed down faster on flat ground.
                                > --
                                > Lee A. Hart Ring the bells that still can ring
                                > 814 8th Ave. N. Forget your perfect offering
                                > Sartell, MN 56377 USA There is a crack in everything
                                > leeahart_at_earthlink.net That's how the light gets in - Leonard Cohen
                                >
                                >
                                >
                                > To unsubscribe from this group, send an email to:
                                > toyota-prius-unsubscribe@egroups.com
                                >
                                >
                              • S. B.
                                Hello, Thanks for the replies on the B gear, I really appreciate it! So the B gear adds funcionality to the regen system. Where I live is very hilly.
                                Message 15 of 25 , Oct 3, 2000
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                                  Hello,
                                  Thanks for the replies on the "B" gear, I really appreciate it! So
                                  the "B" gear adds funcionality to the regen system. Where I live is
                                  very hilly. Mileages in ICE cars really SUFFER because there is a 25
                                  mph speed limit, so you can't "coast" downhill and have to wear your
                                  brakes out.

                                  --- In toyota-prius@egroups.com, Lee Hart <leeahart@e...> wrote:
                                  > S. B. wrote:
                                  > > From what I'm reading, the "B" gear allows for faster recharging,
                                  but
                                  > > in less time. However the same amount of energy is recovered as
                                  in
                                  the
                                  > > "D" gear using just regen, except in a shorter distance? Example:
                                  Say
                                  > > I'm going downhill, but the regen does not have enough force to
                                  bring
                                  > > down the car's momentum and so it still speeds up, but I decide
                                  to
                                  use
                                  > > it anyways and let's say it gets 7 units of electricity (for
                                  example)
                                  > > until I reach down to 50 mph after the downhill grade. Instead of
                                  the
                                  > > "D" gear, I then select the "B" gear and more quickly reach 50
                                  mph;
                                  > > will I get 7 units of energy, in less space? Or this may be the
                                  > > better question to ask: Will using the "B" gear recharge the
                                  > > batteries faster than in the "D" gear?
                                  >
                                  > I can only tell you what seems to be happening, based on my own
                                  limited
                                  > experience with our Prius.
                                  >
                                  > We live at the top of a long hill. If I coast down the hill from
                                  top
                                  to
                                  > bottom in D, I recover 1.5 "E"'s worth of energy (according to the
                                  dash
                                  > display, where each "E" is 50 watt-hours of recovered energy).
                                  >
                                  > But there is a 20 mph speed limit on that hill when school is open.
                                  The
                                  > car coasts too fast in D. If I put it in B, it now coasts down the
                                  hill
                                  > and stays below 20 mph. At the bottom, I still have 1.5 "E"'s worth
                                  of
                                  > energy.
                                  >
                                  > So using B recovers the same amount of energy as D, but keeps your
                                  speed
                                  > slower on hills, or brings your speed down faster on flat ground.
                                  > --
                                  > Lee A. Hart Ring the bells that still can ring
                                  > 814 8th Ave. N. Forget your perfect offering
                                  > Sartell, MN 56377 USA There is a crack in everything
                                  > leeahart_at_earthlink.net That's how the light gets in - Leonard
                                  Cohen
                                • Mike Brigham
                                  Reading my manual, I get the idea that B stands for (IC) engine braking. That last e-mail tends to confirm it in that the same amount of energy units are
                                  Message 16 of 25 , Oct 3, 2000
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                                    Reading my manual, I get the idea that B stands for (IC) engine
                                    braking. That last e-mail tends to confirm it in that the same
                                    amount of energy units are generated either way.

                                    I say this despite getting the opposite answer from a Prius mechanic.

                                    Does anyone have concrete info on this??

                                    -Mike Brigham

                                    --- In toyota-prius@egroups.com, Lee Hart <leeahart@e...> wrote:
                                    > S. B. wrote:
                                    > > From what I'm reading, the "B" gear allows for faster recharging,
                                    but
                                    > > in less time. However the same amount of energy is recovered as
                                    in the
                                    > > "D" gear using just regen, except in a shorter distance? Example:
                                    Say
                                    > > I'm going downhill, but the regen does not have enough force to
                                    bring
                                    > > down the car's momentum and so it still speeds up, but I decide
                                    to use
                                    > > it anyways and let's say it gets 7 units of electricity (for
                                    example)
                                    > > until I reach down to 50 mph after the downhill grade. Instead of
                                    the
                                    > > "D" gear, I then select the "B" gear and more quickly reach 50
                                    mph;
                                    > > will I get 7 units of energy, in less space? Or this may be the
                                    > > better question to ask: Will using the "B" gear recharge the
                                    > > batteries faster than in the "D" gear?
                                    >
                                    > I can only tell you what seems to be happening, based on my own
                                    limited
                                    > experience with our Prius.
                                    >
                                    > We live at the top of a long hill. If I coast down the hill from
                                    top to
                                    > bottom in D, I recover 1.5 "E"'s worth of energy (according to the
                                    dash
                                    > display, where each "E" is 50 watt-hours of recovered energy).
                                    >
                                    > But there is a 20 mph speed limit on that hill when school is open.
                                    The
                                    > car coasts too fast in D. If I put it in B, it now coasts down the
                                    hill
                                    > and stays below 20 mph. At the bottom, I still have 1.5 "E"'s worth
                                    of
                                    > energy.
                                    >
                                    > So using B recovers the same amount of energy as D, but keeps your
                                    speed
                                    > slower on hills, or brings your speed down faster on flat ground.
                                    > --
                                    > Lee A. Hart Ring the bells that still can ring
                                    > 814 8th Ave. N. Forget your perfect offering
                                    > Sartell, MN 56377 USA There is a crack in everything
                                    > leeahart_at_earthlink.net That's how the light gets in - Leonard
                                    Cohen
                                  • RobertSnyder@worldnet.att.net
                                    ... mechanic. ... I see the manual uses the phrase engine braking when discussing what the B selection does, but I think they re just trying to convey the
                                    Message 17 of 25 , Oct 3, 2000
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                                      --- In toyota-prius@egroups.com, "Mike Brigham" <smithbrigham@i...>
                                      wrote:
                                      > Reading my manual, I get the idea that B stands for (IC) engine
                                      > braking. That last e-mail tends to confirm it in that the same
                                      > amount of energy units are generated either way.
                                      >
                                      > I say this despite getting the opposite answer from a Prius
                                      mechanic.
                                      >
                                      > Does anyone have concrete info on this??
                                      >
                                      > -Mike Brigham
                                      >

                                      I see the manual uses the phrase "engine braking" when discussing
                                      what the B selection does, but I think they're just trying to convey
                                      the same concept that people are used to, namely, when you take your
                                      foot off the accelerator, the car slows down because of something
                                      going on under the hood. The effect is greater in the "2" position
                                      of a typical automatic, and that effect is simulated in the Prius
                                      with the "B" position. It's unfortunate that the manual doesn't have
                                      a section with better explanations for those who are mentally ready
                                      for it.

                                      I find it very unlikely that the B position ever uses the I.C.E. to
                                      help slow the Prius. The battery is able to provide up to 21 kW peak
                                      power, so I doubt it can accept much more than that during recharge.
                                      The main electric motor (MG #2) has a rated output of 33 kW above
                                      1040 RPM (about 20 MPH). It can probably generate close to that
                                      during maximum generation. So it would be pointless to also run the
                                      smaller generator (MG #1) as a generator because there would be no
                                      place for the electricity to go (except heat and who wants more of
                                      that in their motor/generators). The I.C.E cannot apply torque to
                                      the wheels without receiving torque from MG #1. The generator can
                                      only cause the I.C.E. to apply reverse torque if it is trying to slow
                                      down while spinning backward (opposite the direction that the engine
                                      spins). MG #1 would probably have to be spinning at around 1000 RPM
                                      backward in order to get a useful amount of torque acting as a
                                      generator (it would be foolish to act as a motor). So it would only
                                      be practical to use this arrangement above about 35 MPH, a range
                                      where MG #2 can easily do the max regenerative braking the batteries
                                      can handle.

                                      To summarize: Above 20 MPH, the main motor can do all the useful
                                      regeneration possible. Below 35 MPH the smaller generator cannot
                                      force braking torque through the engine.

                                      So while it's possible to use the engine as part of a regenerative
                                      braking scheme from MG #1 (the little generator), it is only possible
                                      above about 35 MPH, gives you nothing additional other than heat, and
                                      adds wear and tear to the I.C.E. unnecessarily. Rather than heat MG
                                      #1 unnecessarily, I suspect Toyota opted to let you start heating the
                                      brake pads at that point.

                                      An interesting question is: does the THS continue to employ
                                      regenerative braking when the batteries are topped off? At that
                                      point all the energy would go into heating motor/generators,
                                      rectifiers, or batteries. I've never filled my batteries, so I don't
                                      know what happens.

                                      Robert Snyder
                                    • Paul Opitz
                                      There were earlier postings, here or on Yahoo, by Priusman that explained that the B position is included so as to simulate the lower gears in normal
                                      Message 18 of 25 , Oct 3, 2000
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                                        There were earlier postings, here or on Yahoo, by Priusman that explained that the B position is included so as to simulate the lower gears in "normal" automatic transmissions, to allow you to use engine braking on long hills. He did not, however, discuss the relative effects on charge recover between the two modes.
                                         
                                        p
                                        ----- Original Message -----
                                        Sent: Tuesday, October 03, 2000 8:23 PM
                                        Subject: [toyota-prius] Re: When do you use N, as opposed to D or B?

                                        Reading my manual, I get the idea that B stands for (IC) engine
                                        braking. That last e-mail tends to confirm it in  that the same
                                        amount of energy units are generated either way.

                                        I say this despite getting the opposite answer from a Prius mechanic.

                                        Does anyone have concrete info on this??

                                        -Mike Brigham

                                        --- In toyota-prius@egroups.com, Lee Hart <leeahart@e...> wrote:
                                        > S. B. wrote:
                                        > > From what I'm reading, the "B" gear allows for faster recharging,
                                        but
                                        > > in less time. However the same amount of energy is recovered as
                                        in the
                                        > > "D" gear using just regen, except in a shorter distance? Example:
                                        Say
                                        > > I'm going downhill, but the regen does not have enough force to
                                        bring
                                        > > down the car's momentum and so it still speeds up, but I decide
                                        to use
                                        > > it anyways and let's say it gets 7 units of electricity (for
                                        example)
                                        > > until I reach down to 50 mph after the downhill grade. Instead of
                                        the
                                        > > "D" gear, I then select the "B" gear and more quickly reach 50
                                        mph;
                                        > > will I get 7 units of energy, in less space?  Or this may be the
                                        > > better question to ask:  Will using the "B" gear recharge the
                                        > > batteries faster than in the "D" gear?
                                        >
                                        > I can only tell you what seems to be happening, based on my own
                                        limited
                                        > experience with our Prius.
                                        >
                                        > We live at the top of a long hill. If I coast down the hill from
                                        top to
                                        > bottom in D, I recover 1.5 "E"'s worth of energy (according to the
                                        dash
                                        > display, where each "E" is 50 watt-hours of recovered energy).
                                        >
                                        > But there is a 20 mph speed limit on that hill when school is open.
                                        The
                                        > car coasts too fast in D. If I put it in B, it now coasts down the
                                        hill
                                        > and stays below 20 mph. At the bottom, I still have 1.5 "E"'s worth
                                        of
                                        > energy.
                                        >
                                        > So using B recovers the same amount of energy as D, but keeps your
                                        speed
                                        > slower on hills, or brings your speed down faster on flat ground.
                                        > --
                                        > Lee A. Hart                Ring the bells that still can ring
                                        > 814 8th Ave. N.            Forget your perfect offering
                                        > Sartell, MN 56377 USA      There is a crack in everything
                                        > leeahart_at_earthlink.net  That's how the light gets in - Leonard
                                        Cohen


                                        To unsubscribe from this group, send an email to:
                                        toyota-prius-unsubscribe@egroups.com


                                      • Christopher Culp
                                        I wonder what you d get if you let it go half-way down in D and the rest in B? c.culp
                                        Message 19 of 25 , Oct 4, 2000
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                                          I wonder what you'd get if you let it go half-way down in D and the rest
                                          in B?
                                          c.culp


                                          bfroelich@... wrote:
                                          >
                                          > Interesting! I would have guessed that you'd recover more energy in
                                          > B than in D, not the same amount. This pretty much blows what I said
                                          > in #1724 out of the water. Glad to have some real-world data to set
                                          > me straight.
                                          >
                                          > --- In toyota-prius@egroups.com, Lee Hart <leeahart@e...> wrote:
                                          > >
                                          > > I can only tell you what seems to be happening, based on my own
                                          > limited
                                          > > experience with our Prius.
                                          > >
                                          > > We live at the top of a long hill. If I coast down the hill from
                                          > top
                                          > to
                                          > > bottom in D, I recover 1.5 "E"'s worth of energy (according to the
                                          > dash
                                          > > display, where each "E" is 50 watt-hours of recovered energy).
                                          > >
                                          > > But there is a 20 mph speed limit on that hill when school is open.
                                          > The
                                          > > car coasts too fast in D. If I put it in B, it now coasts down the
                                          > hill
                                          > > and stays below 20 mph. At the bottom, I still have 1.5 "E"'s worth
                                          > of
                                          > > energy.
                                          > >
                                          > > So using B recovers the same amount of energy as D, but keeps your
                                          > speed
                                          > > slower on hills, or brings your speed down faster on flat ground.
                                          > > --
                                          > > Lee A. Hart Ring the bells that still can ring
                                          > > 814 8th Ave. N. Forget your perfect offering
                                          > > Sartell, MN 56377 USA There is a crack in everything
                                          > > leeahart_at_earthlink.net That's how the light gets in - Leonard
                                          > Cohen
                                          >
                                          > To unsubscribe from this group, send an email to:
                                          > toyota-prius-unsubscribe@egroups.com
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