Berkeley CSUA MOTD:Entry 30191
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2018/08/15 [General] UID:1000 Activity:popular
8/15    

2004/5/12 [Transportation/Car/Hybrid] UID:30191 Activity:high
5/12    http://www.wired.com/news/autotech/0,2554,63413,00.html?tw=wn_tophead_1
        Honda's Civic Hybrid is rated by the EPA to get 47 miles per gallon
        in the city, and 48 mpg on the highway. After nearly 1,000 miles of
        mostly city driving, Blackshaw was getting 31.4 mpg. "I feel like a
        complete fraud driving around Cincinnati with a license plate that
        says MO MILES," says Blackshaw, who claims that after 4,000 miles
        his car has never gotten more than 33 mpg on any trip.
        (Also, if you check the Prius msg boards linked from the article,
        it appears those drivers get 45+ mpg.  2004 Prius >> Civic Hybrid.
        But I still think it's easy to hit some poor pedestrian who didn't
        hear you coming.)
        \_ There's very little difference in road noise at speed between a
           hybrid and a standard car.
           \_ "at speed" is definitely not the situation I'm imagining.
              I am now assuming I don't need to give examples of the situations
              I'm actually afraid of.
        \_ Toyota is ahead on the hybrid tech, they've done it longer.
        \_ That's really sad,  I get 33-37 in my regular Honda Civic.
        \_ I used to get 38-42 combined in my crappy '87 Ford Escort.  Maybe
           it's the way he drives.  Does electric motor have the same problem
           as gas engine where rapid acceleration consumes more energy than
           gentle acceleration in order to reach the same final speed?
           \_ It's probably something like that.  The VW diesels say they
              can get over 40 mpg, but you have to shift at like 2000 rpm
              to get that kind of mileage.  Many people get only around 30
              some when driving like they would with a normal car.
        \_ Is it correct that they'll use the gas engine to augment the
           electric engine during hard acceleration?
           \_ The gas engine is the primary means of power.  The batteries are
              charged *solely* by the brakes storing energy in them.  *If* the
              batteries have power, the electric will try to take over for the
              gas engine, but in a high-horsepower situation both will operate
              together.
              \_ Just from the brakes?  So that means that living in a hilly
                 place makes a huge difference, right?
              \_ Is that true for all hybrids?  I thought it was supposed
                 to be that that gas engine generated electricity, which
                 moved the car.  If it's just based on brakes, unless you
                 were very careful you'd just be driving a regular car
                 with too many batteries.
                 \_ OK, hybrid cars shouldn't be thought of as some
                    revolutionary new propulsion technology.  All they are is
                    small gasoline-powered cars with an added system that
                    recaptures energy normally wasted when you hit the brakes.
                    If you live in a hilly area or have to use the brakes a
                    lot, a hybrid will save over a conventional car.  If you
                    drive a lot at constant speed or accelerate hard, you
                    won't save much.
                    Simply having the gasoline engine generate electricity for
                    the electric motor will waste power, because every time you
                    convert forms of energy, you lose.  A normal car converts
                    chemical, to pressure to motion.  If you then convert
                    motion to electricity and then back into motion, you've
                    wasted energy and had to cary around an electric motor too.
                    -dgies ( majored in Physics)
                    \_ dewd, if you checked the Prius web site, you would see
                       that it said the gas engine would recharge the battery
                       if the batteries were low.  Also, further refinements
                       include shutting off the gas engine entirely while
                       the car is stationary.  Note that this is linked to
                       the first statement.
                       \_ Directly charging the batteries with the gas engine
                          *is* wasteful of energy.  However, since the hybrids
                          have small engines, it makes sense to keep some
                          juice in the batteries for when you need some extra
                          horsepower. -dgies
                          \_ okay, as long as we know the gas engine does
                             charge the battery at appropriate times -- it's
                             not all braking action as asked by a previous
                             poster -- and one acknowledges the benefit of
                             having the gas engine turn off completely while
                             the vehicle is stationary.  Finally, the
                             battery is also charged when going downhill by
                             applying automatic braking, and the gas engine
                             may also turn off completely.
                          \_ You are just wrong dgies. Do you understand
                             how a diesel electric train engine works? The
                             hybrids work the same way.
                             \_ Those dang SCIENTISTS and ENGINEERS!
                             \_ Actually, this is not quite true.  There
                                is no physical connection (via transm.)
                                between the diesel engine and to the
                                locomotives wheel.  Prius has CVT as
                                mentioned below.  Prius uses the electric
                                motor to either supplement energy (from
                                the batteries) or used as a generator
                                to capture excess engery (either from
                                the engine or from the wheels "braking").
                                Diesel-Electric uses the engine soley
                                as a power-plant for the electric motor
                                (which connects to the wheels).  The
                                reason behind this is that the narrow
                                powerband of the diesel engine would
                                require a transmission with about 25
                                gears.  BTW, you can use the elec. motor
                                also to brake a locomotive.  Think of
                                it as a giant hair blow dryer.  Instead
                                of storing the energy in a battery, it
                                is used to generate heat.
                                \_ Why doesn't the locomotive also store the
                                   electric energy from braking (or at least
                                   some of it) instead of wasting it?
                                   \_ I guess because freight locomotives
                                      tend to do long haul and not do
                                      quick stop-n-go runs.  It probably
                                      doesn't make economical sense (and
                                      much like hybrid doesn't "shine" in
                                      high speed highways).
                     \_ With CV transmission, you can get "infinite" gear
                        ratio (versus the traditional 1st gear, 2nd, etc).
                        This way, the computer can operate the gas engine
                        at the most efficient RPM without directly
                        affected by the speed of the car.  Any "excess"
                        energy generated by the engine can be used
                        to recharge the battery.
                        \_ Yeah but then you don't get something to mash
                           about while bombing around the hills.  -John
                        \_ CVT isn't specific to hybrids. MINI's and Audi
                           A4's have them.
                           \_ are they something that we should expect to see
                              on all cars in the near future, or are they too
                              expensive? (or is there some other reason that
                              this would be undesirable?)
                              \_ I imagine they're probably more expensive and
                                 less proven reliability.
                           \_ Civic HX (a gas-only car) has CVT also.
                \_ it's my understanding that the Honda hybrids are primarily
                   gas and use the electric motor to supplement it whereas the
                   Toyota Prius is the other way around.
2018/08/15 [General] UID:1000 Activity:popular
8/15    

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www.wired.com/news/autotech/0,2554,63413,00.html?tw=wn_tophead_1
But after a few months of commuting to his job in Cincinnati, Blackshaw's hybrid euphoria vanished as his car's odometer revealed that the gas mileage he was hoping for was only a pipe dream. Honda's Civic Hybrid is rated by the EPA to get 47 miles per gallon in the city, and 48 mpg on the highway. After nearly 1,000 miles of mostly city driving, Blackshaw was getting 314 mpg. "I feel like a complete fraud driving around Cincinnati with a license plate that says MO MILES," says Blackshaw, who claims that after 4,000 miles his car has never gotten more than 33 mpg on any trip. The tenor of Blackshaw's blog shifted from adulation to frustration after his Honda dealer confirmed that his car was functioning properly, and that there was nothing he could do. Consumer Reports indicates that hybrid cars get less than 60 percent of EPA estimates while navigating city streets. In Consumer Reports' real-world driving test, the Civic Hybrid averaged 26 mpg in the city, while the Toyota Prius averaged 35 mpg, much less than their respective EPA estimates of 47 and 60 mpg. Hybrid cars performed much closer to EPA estimates in Consumer Reports' highway tests. EPA test is a lab simulation, Consumer Reports puts the cars on the streets and measures the fuel consumed to more accurately reflect gas mileage. The 19-year-old EPA tests for city and highway mileage actually gauge vehicle emissions and use that data to derive an estimated fuel-efficiency rating. The EPA tests pre-production vehicles in a lab to simulate vehicle starts and stops on crowded city streets and open road conditions.