Electric Motorcycle Armchair Engineers Discussion Thread. Truths, Half-truths, and Myths.

Discussion in 'Electric Motorcycles' started by T.S.Zarathustra, Mar 22, 2019.

  1. Mambo Dave

    Mambo Dave I cannot abide.

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    You got me feeling bad that I just bought a 2019 Prius. But... I'm saving fuel costs (and maintenance costs - it's not only super-economical in one area), so the environment can suck it!

    :D
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  2. liberpolly

    liberpolly Nu, shoyn, nudnick!

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    A report published in 2011 about what they think would be a 2015 model vehicle. That's your claim?

    Look, I'llt ry reasoning with you one more time. The only major part that inherently needs emitting carbon in vehicle production is the steel - adding coal to peel oxygen from the iron is an essential part of the technology. Everything else, aluminum, copper, lithium, plastics, etc. can be produced using electricity. Electricity to produce and charge the vehicles can be produced without emitting carbon - by nuclear power stations, solar, etc. So while you're trying to make an impression that electric vehicles *inherently* emit carbon, this is bullshit - the current processes that are emitting carbon exist *because* of historical reliance on fossil fuels, and are being rapidly replaced. Not rapidly enough, but still.
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  3. magnussonh

    magnussonh Adventurer

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    Don't forget that batteries lose more than just capacity when they get older, they also lose the capability to maintain voltage under load. Loss of capacity only means loss of range. Loss of voltage means loss of power.

    PS. I had to look up the word. By the way it has been used here I thought it meant something different. :D
    "Snarky is a witty mannerism, personality, or behavior that is a combination of sarcasm and cynicism. Usually accepted as a complimentary term."
    "Snarky is used to describe speech with a specific emotional tone, typically a form of sarcasm informed by cheekiness and a mild, playful irreverence."
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  4. T.S.Zarathustra

    T.S.Zarathustra Been here awhile

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    Why would you feel bad about that? By the way, I have never said that electric cars, or hybrids, are bad for the environment. Just that they are not as good as some make them out to be. They pollute more when made, but pollute less while running. If you keep them running long enough, they'll pollute less than similar ICE.

    Here is a Paradox. If you keep one ICE running for much longer than another identical ICE. Then the one that runs longer will pollute more. But it will pollute less per mile than the one that ran shorter.

    Thank you for the praise. I also think they have different meaning in mind for that word. :lol3

    Do you have sources for that claim? Just kidding :jack.
    I had forgotten about that. Not only do your cells lose capacity and therefore range. They also drop the voltage under load, and as you point out, lose power. But it is even worse. The voltage drop is on top of effectively smaller capacity batteries. It's a double punch, your power will drop on top of your range reduction. Of course, if you drive slower your power loss will matter less, and your range will increase again. Maybe you're on to something.
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  5. T.S.Zarathustra

    T.S.Zarathustra Been here awhile

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    Hmm, these must be wrong then.
    "In 2011 direct (process) emissions of greenhouse gas (PFCs, carbon inputs, fuels) were 1.87 tonnes of CO2-e per tonne of aluminium."
    https://aluminium.org.au/climate-change/aluminium-smelting-greenhouse-performance/
    "Several tonnes of carbon dioxide are being released, even before electric batteries leave the factory."
    https://www.thegwpf.com/new-study-large-co2-emissions-from-batteries-of-electric-cars/
  6. liberpolly

    liberpolly Nu, shoyn, nudnick!

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    From your own link:

    over 80 per cent of smelting greenhouse gas emissions are indirect (electricity-related) emissions
    From your second link:

    The calculation is based on the assumption that the electricity mix used by the battery plant is based by more than half by power generated by fossil fuels.
    Clear enough?
  7. magnussonh

    magnussonh Adventurer

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    Basically the only sources are the pile of textbooks I had to plow through to get my degree in electrical engineering. Here are some books that some people would gain something from reading. Some I had to study, other were recommended by my professors and colla as a way of widening my knowledge of the business.

    You are right in that less speed requires less power. So you can have lighter motors and fewer batteries. This leads to lighter vehicle that increase range. Alas, too many people are blinded by "Too much power is not enough" for that to actually work.
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  8. liberpolly

    liberpolly Nu, shoyn, nudnick!

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    The problem is that if an electric motorcycle is too slow, it becomes a heavy electric bicycle, and its utility becomes severely limited.

    The weight also doesn't matter as much as it may seem to an electrical engineer :) At constant speed on even surface it doesn't matter at all; with the proliferation of smart regenerative braking, whatever you lose on assent and acceleration, you mostly gain on descent and deceleration. In the end, it becomes a rounding error compared to the weight of the rider and luggage.
  9. SteveAZ

    SteveAZ Long timer

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    With the electric bike air resistance is by far the greatest impact on speed vs. efficiency

    I'll be it's pretty much the same with motos
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  10. T.S.Zarathustra

    T.S.Zarathustra Been here awhile

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    I've "ploughed through" 4 of those, and many similar. :-)

    You're right. Make the Tesla Model 3 ~ 110 hp instead of ~ 330. That should be enough for at least 80 mph, not much, but enough for all law abiding citizens. Motor and control unit weight could probably be cut in half, batteries probably by maybe 20%, so total weight of the car would drop quite a bit. Since most power is used when accelerating (as can be seen by cars having lower mileage in cities, even if average speed is lower than the highway), dropping the weight would increase the range close to the same as current car. It would also decrease rolling resistance from the tires. And, of course, it would decrease the pollution from building the car. Win, win and win. :D
  11. liberpolly

    liberpolly Nu, shoyn, nudnick!

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    Tesla 3 motor weighs less than 100 lbs, battery weight is about 1/4th of the total car weight, so the overall reduction in weight will be what, 5%? Not worth it for Tesla to lose the market share.

    You people are really looking for gains in all the wrong places. The reason the electric motors on EVs are over-powered is to compensate for the missing transmission, which is, overall, a huge improvement in weight, efficiency, and reliability.
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  12. magnussonh

    magnussonh Adventurer

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    Zarathustra has said that when you purchase new EV it has caused more pollution than comparable ICE. EV will make up for it by polluting less when being used. You are borrowing pollution against future cleaner EV running. That math works nicely as long as nothing happens.
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  13. T.S.Zarathustra

    T.S.Zarathustra Been here awhile

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    Nice way of putting it. Your return depends on how clean your energy sources are.
  14. liberpolly

    liberpolly Nu, shoyn, nudnick!

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    But a lot of things are happening, and have happened since the math he relies on was done. The numbers from 2011 he used are not even nearly correct today, and will be even less relevant in the next 8 years.
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  15. WagonWillie

    WagonWillie Been here awhile

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    Not the case with my Zero SR: I only get back about 10 to 15% with regeneration. I think it's mostly due to the charger not being able to shunt the regen quickly enough due to its limited capacity.
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  16. WagonWillie

    WagonWillie Been here awhile

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    Yeah, that's why this looks promising: https://newatlas.com/linear-labs-hunstable-electric-motor/60974/
  17. liberpolly

    liberpolly Nu, shoyn, nudnick!

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    Yeah, they need to up the ante here.
  18. SteveAZ

    SteveAZ Long timer

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    Catching regen energy from hard braking is difficult - batteries just can't take the energy quickly enough

    Maxwell makes "supercapacitors" up to the task but that adds size, cost and weight that in smaller vehicles may be hard to justify

    https://www.maxwell.com/products/ultracapacitors/
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  19. liberpolly

    liberpolly Nu, shoyn, nudnick!

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  20. liberpolly

    liberpolly Nu, shoyn, nudnick!

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    Yeah, probably not that important for a motorcycle where most of the energy is spent on overcoming air resistance.