Did you consider the Honda Clarity before your Prius Prime?

Discussion in 'Prime Main Forum (2017-Current)' started by Skapruisprime, Feb 18, 2018.

  1. Lee Jay

    Lee Jay Senior Member

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    It's' just beyond your comprehension.

    If you think adding more than half a ton of dead weight to a car doesn't change mileage, you might want to patent the way you avoided acceleration losses and rolling friction.
     
  2. Lee Jay

    Lee Jay Senior Member

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    Since they aren't in mass production, no one knows. Life span is 15 years minimum, probably far longer. Same with the 12 years propane tanks last before needing recertification.
     
  3. Oniki

    Oniki Active Member

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    And reality, not to mention simple facts, is beyond yours.
     
    #103 Oniki, Apr 12, 2018
    Last edited: Apr 13, 2018
  4. Oniki

    Oniki Active Member

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    This has been solved for a long time.

    Rolling friction is about 90 Newtons per 1000 Kg extra mass
    Acceleration losses are markedly attenuated by a good regen system, and max regen power is about proportional to battery size for the cars we drive. As we add battery weight, the improved regen offsets the weight penalty. You can see this by considering the following: increasing the range of a e.g. Tesla from 200 to 300 miles requires a 50% increase in battery capacity but only a ~ 10% increase in mass.

    The end result is that the energy penalty from extra battery weight is nowhere near your guesses; and if you had looked at actual data you would have realized that your "analysis" was deficient.
     
    #104 Oniki, Apr 12, 2018
    Last edited: Apr 12, 2018
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  5. bwilson4web

    bwilson4web i3 and Prime

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    Perhaps @john1701a can provide a specific reference but in the early days of hybrid skepticism, a similar claim was made against the Prius. I think Penn and Teller made that claim once but it was common enough in some of the automotive press.

    Inertial and gravitational motions are conservative fields ... energy put in can be recovered. It is only friction and aerodynamic drag that are not conservative. One pedal driving in our BMW i3-REx really brought that home.

    Bob Wilson
     
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  6. Since2002

    Since2002 Senior Lurker

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    The chart shows $5.55 / kg for hydrogen, however prices seem to be more than double that, although it's nearly impossible to find specific information online from actual owners. Gas Buddy doesn't show hydrogen prices :(

    There doesn't seem to be a "Hydrogen Buddy" website :rolleyes:

    I could only find a few data points:

    Feb 2017 MotorTrend, beginning of long term Mirai test drive in Southern California, the article stated hydrogen costs "around $15 per kg "

    Sep 2017 MotorTrend, conclusion of long term Mirai test drive in Southern California, the article stated hydrogen costs "$15 per kg or more"

    Nov 2017 The San Diego Union-Tribune Clarity FCEV, the article reported that it cost $78.32 to add 4.7 kg to the tank. That works out to $16.66 per kg.

    Mar 2018 Mirai forum. One lone commentator brought up fuel prices, stating only that prices in Southern California were fairly standard however "a couple of places" were $2.00 cheaper, thus they advised shopping around. My comment - hydrogen stations are few and far between, driving to one of the few lower priced stations may not be practical for most FCEV owners.

    Maybe @HPrimeAdvanced can get a sample of some current hydrogen prices during his journeys in Southern California.

    I'm not sure how they came up with $5.60 per gallon equivalent, even using their price of $13.99 per kg. I ran a cost comparison between the Clarity FCEV and PHEV, which are identical cars other than the powertrain. There is a slight weight difference of 4,134 vs 4,052.

    Clarity FCEV

    miles / kg = 67
    fuel price / kg = $13.99
    fuel cost per mile = $0.21

    Clarity PHEV

    HV mpg = 42
    fuel price / gal = $3.40 (average Orange County)
    fuel cost per mile = $0.08

    The fuel cost per mile for FCEV is 2.6 times as much as PHEV. In order for PHEV to have the same cost per mile as FCEV gasoline would have to be $8.92 per gallon.
     
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  7. HPrimeAdvanced

    HPrimeAdvanced Senior Member

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    "Hydrogen is sold by the kilogram
    instead of the gallon and at the station we used to fill the Mirai in La Canada, Calif., it was $16.63 per kilogram. The Mirai was three-quarters empty at that point and the tanks hold around 5 kilograms of hydrogen, so it took 3.8 kilograms to fill back it up at a cost of $63.51. The trip meter read 195.3 miles at that point. That put the cost per mile at around $0.33. This is still much higher than the cost of fuel for a gasoline vehicle"
    From cars.com and hopefully answers your question regarding hydrogen-fueled cars.


    Posted via the PriusChat mobile app.
    AChoiredTaste.com
     
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  8. Since2002

    Since2002 Senior Lurker

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    Thanks although that article was written September 2016, I was trying to get a current price . If you happen to drive past a hydrogen station can you check the price if it's not too inconvenient, although I'm pretty sure it's not posted on a big neon sign the price is probably available only on the pump itself.. A list of stations can be found here:

    Stations Map | California Fuel Cell Partnership

    Looks like they have one in Anaheim on La Palma Ave. at Tustin, down the street from the Fry's Electronics store that I used to go to when I lived there. It looks like the pump is located behind the 76 station, in fact in Google Maps street view there happened to be a hydrogen truck parked at the pump. In the photo below the pump is in the background under that overhang, the thing that looks like a blue phone booth.


    Hydrogen station Anaheim.PNG
     
  9. Bill Norton

    Bill Norton Senior Member

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    Very interesting point !

    Another great point! Recert the tanks. These are still the early days, folks. Hang in there.
    Lee, Thanks for sharing your knowledge on this subject on this very off subject thread!

    Please don't call him and his theories on 'skeptics' in on this thread.
    This thread is already very off topic.
    But as educational as Hay-L !!(y)

    Folks, We need to store excess electricity. Hydrogen is a way to store and transport clean energy.
    It's funny to hear so much skepticism on this site......
     
  10. Lee Jay

    Lee Jay Senior Member

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    With energy losses both ways. Those losses are usually called "acceleration losses".
     
  11. Lee Jay

    Lee Jay Senior Member

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    You are quite clueless.

    I have a full aero and rolling friction model built into my spreadsheet. I usually use 0.01 for a rolling friction coefficient for LRR tires which is pretty close to your mixed-unit numbers above. I use the fact that about 2/3 of all losses incurred during the life of a typical car are rolling friction (average speeds for passenger cars are quite low) and the fact that a P40 car will do about 3/4 of its life cycle mileage on grid electricity. It's quite easy to demonstrate that a 450 mile range battery at 200Wh/kg and 85% efficiency consumes as much rolling friction and acceleration losses over its life as at 33% H2 system does at 1000Wh/kg covering only 1/4 of the total miles (combined with a 40 mile range 85% efficient battery for the other 3/4).

    Do the math yourself - correctly this time.
     
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  12. Since2002

    Since2002 Senior Lurker

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    Well the OP didn't exactly say which version of the Clarity he was asking about :ROFLMAO:

    At least that is what I plan to tell the judge in case I get hauled into OT court. Although the OP did use terms like "EV range" and "Touring" which is not good for my case. Maybe I'll just take the fifth.
     
  13. Trollbait

    Trollbait It's a D&D thing

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    Varies by the unit. An under the sink model that operates at tap pressure might provide it, but those produce a lot of waste brine. The most efficient might dump 4 gallons for every gallon of purified drinking water.

    The question really is, how little waste brine do you want to make?

    That assumes the hydrogen is ignited after it leaves the car. Hydrogen has a wide range of air to fuel ratios at which it can combust. So a leak igniting within the car's body can't be ruled out.

    The more expensive type IV CNG tanks could have a life span of 25yrs. CNG only fills up to 3600psi though. The Mirai has 15 yr tanks going by a label on the fuel flap. These tanks can't be recertified. The US DOT also requires CNG tanks to be inspected at 3yrs or 36000 miles.

    What I posted was based on a 2015 report. It likely used something like the average fuel economy of new cars sold that year for the comparison, or even included trucks in that average. That tended to be 20 to 25 MPG.
     
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  14. Lee Jay

    Lee Jay Senior Member

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    It was never in the passenger compartment in the first place.

    And on a fuel cell car, there's virtually no ignition sources available like the catalytic converter on a gas car. Remember, there are over 150,000 gas car fires every year just in the US.
     
  15. bwilson4web

    bwilson4web i3 and Prime

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    Orbiting satellites, moons, and planets would suggest something else.

    Bob Wilson
     
  16. Lee Jay

    Lee Jay Senior Member

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    I can't tell if you're kidding around or not.

    Acceleration causes propulsion losses - I^2R losses in battery, power electronics and motor, and switching losses in the power electronics.

    Deceleration causes propulsion losses - I^2R losses in battery, power electronics and motor, and switching losses in the power electronics.

    Coasting has neither one, just rolling friction and air drag.

    Rapidly moving from 25 to 35 to 25 will use more energy than steady 30. This should be obvious.
     
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  17. Trollbait

    Trollbait It's a D&D thing

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    I didn't say cabin, but car. The tank is mounted down low because of weight. This means any leaking hydrogen has to work its way up through the frame of the car with nooks within the frame to potential to form pockets of hydrogen. Leaks can also happen along the fuel lines.

    All it takes for ignition is a spark from a faulty switch or wire with worn insulation. Many car fires have had such innocuous starting points without any gasoline even contributing to it.
     
  18. Lee Jay

    Lee Jay Senior Member

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    No, the gas goes around the car and up. Diffusion of hydrogen in air is extremely fast. Heck, it's hard to contain in a tank. It's really hard to contain in open air to get to the lower flammability limit. You generally need a building around it.
     
  19. Oniki

    Oniki Active Member

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    Garbage in, garbage out.

    The EPA has a nice graphic, based on work done on a LEAF from 2012, that shows where energy is used in moving a car. They estimate for the combined cycle that about 22.5% is rolling friction. It then follows that an increase in car mass 10% will increase car consumption per mile by ~ 2.2% overall from that component ... which is VERY close to what we see when two Teslas are compared that vary by 100 miles in range.

    Screen Shot 2018-04-13 at 4.27.14 PM.jpg
     
    #119 Oniki, Apr 13, 2018
    Last edited: Apr 13, 2018
  20. Lee Jay

    Lee Jay Senior Member

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    Like I said, you are very clueless.

    The 2/3 number I quoted was between aero (1/3) and rolling friction (2/3). All the other losses are accounted for separately (for example, they quoted energy lost in charging as 16%, I quoted battery efficiency as 85%, which are only 1% apart).

    Your chart says 39.4% rolling friction, 60.6% aero - for the EPA combined city/highway driving cycle, which is a cycle that doesn't come close to matching average driving over the life of the average car. The real average driving cycle is much slower than the cycle quoted for a number of reasons, including traffic, residential driving, stop lights, parking lots, and so forth. Plus, do you really think a 2012 Leaf is an average car?

    2/3 rolling 1/3 aero is close to right and your chart supports that.
     
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