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Re: [toyota-prius] Re: Toyota FT-bh Teaser

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  • Walter Lee
    With respect to the electric portion of a hybrid s contribution to fuel efficiency this is what I ve learn so far:   1) If the electric motors are used with
    Message 1 of 22 , Feb 29, 2012
      With respect to the electric portion of a hybrid's contribution to fuel efficiency this is what I've learn so far:
       
      1) If the electric motors are used with only electricity that is generated by excess energy from hi speeds ( that is coasting downhill) or by recovered energy from braking - then electric motors increase fuel efficiency.
       
      2) If the electric motors are used with electricity that is generated by the gasoline engine while its standing still or at low speed - then the electric motors decrease fuel efficiency.   Instead of recharging the electric motors automatically when the battery power runs less than 45% - a better power usage solution might be for a hybrid severely limit hi drain usage like the electric motor until the battery power is recharged over 55% by excess speed energy and by regenerative braking. Currently - to get better MPG on  my 3rd gen Prius I do this manually with a ScangaugeII.
       
      3) If the electric motors use electricity is generated by outside source (as a plug-in hybrid ) then the electric motor only appears to increase fuel efficiency because the cost of electrical power generation off-loaded to an outside source ( as a external AC plug). Once you include the cost of the electric power generation - to the fuel efficiency equation - the overall fuel efficiency cost drops and the total fuel cost goes up.
       
      Overall fuel efficiency of any vehicle at high speed (>55mph) is dependent on drivetrain efficiency (matching a low weight to hi power motor with an efficient transmission),  an aerodynamic design with a very low frontal surface, low curb weight, and low rolling resistant,  Overall fuel efficiency of any vehicle at a low speed (<25 mph) is less dependent on aerodynamic design and frontal surface and more dependent on curb weight and very low rolling resistance. A low speeds - the perfect vehicle would be something akin to a Maglev - something that rides on cushion of air with no rolling resistance at all.
       
      The lower curb weight of the new 2012 Prius c should give it a fuel efficiency edge over my heavier 2010 Prius III hatchback.  I expect the new 2012 Prius c to be the non-plug-in MPG champion for the next few years. 
       
       
      Walter Lee
      aka "HyperDrive 1" on Cleanmpg.com
      2010 Toyota Prius III, Blue Ribbon/Dark Grey, OEM floormats
      Yokohama Avid S33D ( front 50psi/rear 48 psi)
      100% grill blocking (100% top grill/100%bottom grill)
      ScangaugeII (Fwt/AVG, RPM, SoC, GPH)
       
      Odeometer +19600 miles, overall 60.9mpg, avg 18 mpg<-- pretty slow going...
      (hypermiling in stop-n-go congested urban-suburban Washington DC area)
      last tank =2/16/12, 644.8 miles,10.616 gallons/E10RFG87oct/60.7 mpg
       

      From: Levi Smith <LeviGSmith@...>
      To: toyota-prius@yahoogroups.com
      Sent: Tuesday, February 28, 2012 12:41 PM
      Subject: Re: [toyota-prius] Re: Toyota FT-bh Teaser

      Eh, more to my point is that Hybrid is a vague term and doesn't necessarily
      mean anything better...  Indeed, our hybrids have a lot more complexity but
      not much better (if any) mileage than a lot of non hybrids.

      While I think the electric portion is "cool" and "fun", I'm not sure that
      it really adds much compared to a lot of the other non-hybrid cars which
      get more than 40mpg with a lot less complexity...

      I think my main point is that mpg would be a much better goal than
      "hybrid".  There's no inherent benefit to a hybrid.  There are plenty of
      hybrids out there that add a LOT of cost (like $10K+) with that complexity
      and are lucky to pull an extra mpg or two compared to the non-hybrid
      versions.

      I think stickers of mpg or emissions on cars would at least serve a decent
      goal instead of just trying to promote hybrids when they are not
      necessarily the better option...

      Levi

      [Non-text portions of this message have been removed]
    • Stan
      Right on Walter. The only magic of the hybrid concept is that you use a smaller engine at a higher load for better volumetric efficiency and then add an
      Message 2 of 22 , Mar 1, 2012
        Right on Walter. The only magic of the hybrid concept is that you use a smaller engine at a higher load for better volumetric efficiency and then add an electric motor for higher load conditions. (Add regeneration, Atkinson Cycle, low friction, etc>) The Prius C (I have seen it) has a smaller drivetrain, less drag and mass so it will add up to an easy 50mpg. The C will also appeal to a younger crowd with a lower price than the lowest III and colors like Jalepeno Orange ( very bright). Just too cramped inside for me (5' 10" 212lbs)

        [Non-text portions of this message have been removed]
      • Larry Finch
        Walter, Very clear, and completely accurate. Whether a plug-in hybrid improves overall efficiency is a function of the efficiency of the electric power source.
        Message 3 of 22 , Mar 1, 2012
          Walter,

          Very clear, and completely accurate. Whether a plug-in hybrid improves
          overall efficiency is a function of the efficiency of the electric
          power source. It may or may not improve overall efficiency, but it can
          lower operating cost because the cost of electric energy is lower than
          the cost of gasoline energy in most areas. Primarily because the taxes
          on it are lower.

          best,
          Larry

          On Thu, Mar 1, 2012 at 2:27 AM, Walter Lee <waltermlee@...> wrote:
          > With respect to the electric portion of a hybrid's contribution to fuel efficiency this is what I've learn so far:
          >
          > 1) If the electric motors are used with only electricity that is generated by excess energy from hi speeds ( that is coasting downhill) or by recovered energy from braking - then electric motors increase fuel efficiency.
          >
          > 2) If the electric motors are used with electricity that is generated by the gasoline engine while its standing still or at low speed - then the electric motors decrease fuel efficiency.   Instead of recharging the electric motors automatically when the battery power runs less than 45% - a better power usage solution might be for a hybrid severely limit hi drain usage like the electric motor until the battery power is recharged over 55% by excess speed energy and by regenerative braking. Currently - to get better MPG on  my 3rd gen Prius I do this manually with a ScangaugeII.
          >
          > 3) If the electric motors use electricity is generated by outside source (as a plug-in hybrid ) then the electric motor only appears to increase fuel efficiency because the cost of electrical power generation off-loaded to an outside source ( as a external AC plug). Once you include the cost of the electric power generation - to the fuel efficiency equation - the overall fuel efficiency cost drops and the total fuel cost goes up.
          >
          > Overall fuel efficiency of any vehicle at high speed (>55mph) is dependent on drivetrain efficiency (matching a low weight to hi power motor with an efficient transmission),  an aerodynamic design with a very low frontal surface, low curb weight, and low rolling resistant,  Overall fuel efficiency of any vehicle at a low speed (<25 mph) is less dependent on aerodynamic design and frontal surface and more dependent on curb weight and very low rolling resistance. A low speeds - the perfect vehicle would be something akin to a Maglev - something that rides on cushion of air with no rolling resistance at all.
          >
          > The lower curb weight of the new 2012 Prius c should give it a fuel efficiency edge over my heavier 2010 Prius III hatchback.  I expect the new 2012 Prius c to be the non-plug-in MPG champion for the next few years.
          >
          >
          > Walter Lee
          > aka "HyperDrive 1" on Cleanmpg.com
          > 2010 Toyota Prius III, Blue Ribbon/Dark Grey, OEM floormats
          > Yokohama Avid S33D ( front 50psi/rear 48 psi)
          > 100% grill blocking (100% top grill/100%bottom grill)
          > ScangaugeII (Fwt/AVG, RPM, SoC, GPH)
          >
          > Odeometer +19600 miles, overall 60.9mpg, avg 18 mpg<-- pretty slow going...
          > (hypermiling in stop-n-go congested urban-suburban Washington DC area)
          > last tank =2/16/12, 644.8 miles,10.616 gallons/E10RFG87oct/60.7 mpg
          >
          >
          > From: Levi Smith <LeviGSmith@...>
          > To: toyota-prius@yahoogroups.com
          > Sent: Tuesday, February 28, 2012 12:41 PM
          > Subject: Re: [toyota-prius] Re: Toyota FT-bh Teaser
          >
          > Eh, more to my point is that Hybrid is a vague term and doesn't necessarily
          > mean anything better...  Indeed, our hybrids have a lot more complexity but
          > not much better (if any) mileage than a lot of non hybrids.
          >
          > While I think the electric portion is "cool" and "fun", I'm not sure that
          > it really adds much compared to a lot of the other non-hybrid cars which
          > get more than 40mpg with a lot less complexity...
          >
          > I think my main point is that mpg would be a much better goal than
          > "hybrid".  There's no inherent benefit to a hybrid.  There are plenty of
          > hybrids out there that add a LOT of cost (like $10K+) with that complexity
          > and are lucky to pull an extra mpg or two compared to the non-hybrid
          > versions.
          >
          > I think stickers of mpg or emissions on cars would at least serve a decent
          > goal instead of just trying to promote hybrids when they are not
          > necessarily the better option...
          >
          > Levi
          >
          > [Non-text portions of this message have been removed]
          >
          >
          >
          > ------------------------------------
          >
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          > http://autos.groups.yahoo.com/group/toyota-prius
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          > http://autos.groups.yahoo.com/group/toyota-prius
          > Yahoo! Groups Links
          >
          >
          >



          --
          Larry Finch

          N 40° 53' 47"
          W 74° 03' 56"
        • Bruce Richmond
          ... Agreed.   ... At low speeds the electric motor/generators are acting as an electric transmission. To provide any torque to the ring gear attached to the
          Message 4 of 22 , Mar 1, 2012
            --- In toyota-prius@yahoogroups.com, Walter Lee <waltermlee@...> wrote:
            >
            > With respect to the electric portion of a hybrid's contribution to fuel efficiency this is what I've learn so far:
            >  
            > 1) If the electric motors are used with only electricity that is generated by excess energy from hi speeds ( that is coasting downhill) or by recovered energy from braking - then electric motors increase fuel efficiency.

            Agreed.
             
            > 2) If the electric motors are used with electricity that is generated by the gasoline engine while its standing still or at low speed - then the electric motors decrease fuel efficiency.   Instead of recharging the electric motors automatically when the battery power runs less than 45% - a better power usage solution might be for a hybrid severely limit hi drain usage like the electric motor until the battery power is recharged over 55% by excess speed energy and by regenerative braking. Currently - to get better MPG on  my 3rd gen Prius I do this manually with a ScangaugeII.

            At low speeds the electric motor/generators are acting as an electric transmission. To provide any torque to the ring gear attached to the wheels the sun gear attached to a motor/generator must provide resistance, otherwise the ICE just free wheels as if in neutral. So the sun generator produces electric power while providing resistance. That electric power gets fed to the large electric motor attached to the ring gear and/or to the battery.

            Unfortunately excess speed energy isn't always available for charging. The ICE becomes very inefficient under very light load, so there could be times where the extra load of charging the battery actually bumps it up into a range of higher efficiency.

            http://hiwaay.net/~bzwilson/prius/pri_power_eff.jpg

            That stored power can then be used to suppliment the ICE so that it doesn't have to go out of its efficient range when more power is required. I think to a certain extent the Prius does this on its own.

            One of my fuel saving tricks is to let off the gas and get the ICE to shut down, then gently step on the gas to maintain my speed with electric. The fuel saved by having the ICE shut down completely, as opposed to running at light load, more than makes up for the extra fuel used to recharge the battery at a higher efficency level. It might not be as efficient as pulse and glide, but it is more dfficent than a continually running ICE and it doesn't annoy other traffic.
             
            > 3) If the electric motors use electricity is generated by outside source (as a plug-in hybrid ) then the electric motor only appears to increase fuel efficiency because the cost of electrical power generation off-loaded to an outside source ( as a external AC plug). Once you include the cost of the electric power generation - to the fuel efficiency equation - the overall fuel efficiency cost drops and the total fuel cost goes up.

            If your main concern is cost/mile a good electric can go a mile on about .3 KW hrs of electric. At off peak rates that's under 3 cents/mile, far better than you can do running on the ICE. To take full advantage of this you need a large enough battery pack to cover a reasonable commute, and large enough electric motor(s) so as not to need the ICE under normal conditions. The Volt does better than the Prius, even the Plug-in Prius, in this reguard, but it really isn't that efficent in electric mode, and it is worse when running the ICE.
             
            > Overall fuel efficiency of any vehicle at high speed (>55mph) is dependent on drivetrain efficiency (matching a low weight to hi power motor with an efficient transmission),  an aerodynamic design with a very low frontal surface, low curb weight, and low rolling resistant,  Overall fuel efficiency of any vehicle at a low speed (<25 mph) is less dependent on aerodynamic design and frontal surface and more dependent on curb weight and very low rolling resistance. A low speeds - the perfect vehicle would be something akin to a Maglev - something that rides on cushion of air with no rolling resistance at all.
            >

            Aero drag is the killer at high speeds. Much is made these days about the Cd. but frontal area is just as important. I wish my Prius was as low and narrow as the MG Midget I once had. Tolling resistance matters at all speeds. LRR tires help, but there are other things that could be done. They make disc brakes that pull the pads back when the brakes are released. I know the rear wheels on my 2001, which has drums in back, don't spin as freely as they could. I don't know whether it is the preload on the bearings or friction from the seals, but something is causing a fair amount of drag.

            The regen could be made much more efficent with some super capacitors. I know they don't have the storage density of batteries, but if they could store the energy of a stop from, say, 80 mph then they would smooth over many of the charge/discharge cycles that the battery currently deals with and return ~90% of the energy compared to ~50% for the battery.

            Weight really isn't that big a factor when you have regen. It takes more energy to accelerate but you get some of it back when you slow down. Carrying an additional 800 lbs makes my 2001 a bit sluggish to respond, but it hardly has any effect on mpg.
             
            > The lower curb weight of the new 2012 Prius c should give it a fuel efficiency edge over my heavier 2010 Prius III hatchback.  I expect the new 2012 Prius c to be the non-plug-in MPG champion for the next few years. 

            Like I said, weight doesn't make much difference. From what I have heard the battery pack on the c is smaller, and there were other changes made to save $, so the c ends up getting about 50 mpg. Be nice if they offered an option for the premium components for those more concerned with mpg than the initial purchase price.

            I see no reason to plaster "Hybrid" stickers all over the car. Any improvement depends greatly on how the technology is implemented. IMO some of the hybrids that cost thousands more and improve mpg by 2 or 3 mpg give hybrids a bad name.
             
            >  
            > Walter Lee
            > aka "HyperDrive 1" on Cleanmpg.com
            > 2010 Toyota Prius III, Blue Ribbon/Dark Grey, OEM floormats
            > Yokohama Avid S33D ( front 50psi/rear 48 psi)
            > 100% grill blocking (100% top grill/100%bottom grill)
            > ScangaugeII (Fwt/AVG, RPM, SoC, GPH)
            >  
            > Odeometer +19600 miles, overall 60.9mpg, avg 18 mpg<-- pretty slow going...
            > (hypermiling in stop-n-go congested urban-suburban Washington DC area)
            > last tank =2/16/12, 644.8 miles,10.616 gallons/E10RFG87oct/60.7 mpg
            >  
            >
            > From: Levi Smith <LeviGSmith@...>
            > To: toyota-prius@yahoogroups.com
            > Sent: Tuesday, February 28, 2012 12:41 PM
            > Subject: Re: [toyota-prius] Re: Toyota FT-bh Teaser
            >
            > Eh, more to my point is that Hybrid is a vague term and doesn't necessarily
            > mean anything better...  Indeed, our hybrids have a lot more complexity but
            > not much better (if any) mileage than a lot of non hybrids.
            >
            > While I think the electric portion is "cool" and "fun", I'm not sure that
            > it really adds much compared to a lot of the other non-hybrid cars which
            > get more than 40mpg with a lot less complexity...
            >
            > I think my main point is that mpg would be a much better goal than
            > "hybrid".  There's no inherent benefit to a hybrid.  There are plenty of
            > hybrids out there that add a LOT of cost (like $10K+) with that complexity
            > and are lucky to pull an extra mpg or two compared to the non-hybrid
            > versions.
            >
            > I think stickers of mpg or emissions on cars would at least serve a decent
            > goal instead of just trying to promote hybrids when they are not
            > necessarily the better option...
            >
            > Levi
            >
            > [Non-text portions of this message have been removed]
            >
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