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forget the springs, go with the electricity

Discussion in 'Electronic Components' started by [email protected], May 29, 2007.

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  1. Guest

    Google answers many questions, if you're just PATIENT enough. just
    stumbled across a powerpoint on the web, concise design analysis of
    the problem by a professor of mechanical engineering. The equations
    show why the patent-office file cabinets are littered with ideas for
    spring-stored energy for bicycles which never saw a real factory
    floor.... the energy-storage density just ain't there. His
    recommendation: optimize the electrical approach.

    Ok: who makes the best electrical-assist which encompasses an
    efficient regenerative-braking?

    what's the state of the art of energy-storage capacitors?
     
  2. default

    default Guest

    Search on ultracapacitors lots of info.

    I still like my cable/pulley idea better.
     
  3. Guest

    I still like my cable/pulley idea better.



    ok, you do it on your mountain. maybe you have an angel giving you
    capital at zero interest expense. i don't.
     
  4. DougC

    DougC Guest

    I think the Bionx can do regenerative braking....

    I don't think the electrical means would be the best solution however. I
    have already found that the cost-per-mile of operating a Bionx is
    greater than for operating a gasoline-engine of comparable power, and
    that was assuming flat ground.

    The problem with electrical vehicles is that everybody WANTS small
    lightweight batteries, but they tend not to last very many discharges
    before failing if they are deep-cycled, and if they aren't deep-cycled,
    then you don't get much practical energy storage from them.

    The only way to make electrical batteries that will last a lot of
    discharge cycles is to make them lead-acid and make them BIG and only
    ever discharge them lightly--but you see then,,,, if you want a vehicle
    that can climb hills, then the last thing you want is a bunch of heavy
    batteries powering your hill-climbing vehicle.
     
  5. default

    default Guest

    Mountain topography and type of cargo aside . . . You figure high tech
    state of the art is going to be less expensive than a piece of wire
    and some pulleys? It won't take capital?

    You wouldn't be the first person wanting to get a weight down a
    mountain. Or hill - any mountain worth the name wouldn't be bicycle
    friendly.

    I worked a place in Alaska where we wanted to haul supplies up to a
    mountain lookout, and do it cheaply. We had a very steep cliff face
    and they were using airlifted supplies. Some guy got the idea to use
    a rope and buckets. Water filled a bucket and pulled the supplies up
    in another bucket. Daily re supply with food and equipment versus
    weekly and at a lot lower cost.

    Still needed the copter for changing observers, and no one could take
    more than a month in the 5 X 8 aluminum box they called home. They
    were working on a steel cable to lift men up. The idea was to put one
    guy in a sling at the base another at the top, add enough water to
    bring the up guy down (if necessary). Plan was to use something like
    the old style dial telephones - centrifugal brake to regulate the
    speed - or an off the shelf centrifugal clutch from a riding
    lawnmower. I never saw that working, but have no doubt they could
    make it work.
     
  6. I had a similar idea to build a small railway on my property which would be
    used to bring down firewood from the top of a hill (about 50' elevation). I
    figured I could run it for free, or maybe get extra energy, by using the
    potential energy of the wood. Probably it would not be economically worth
    the effort, but the cool fun factor made it something I wanted to try.
    Having batteries in the vehicle seemed to be a null factor, except that it
    required bigger motors or slower gearing, and maybe more rolling
    resistance. I also considered electrifying the rails, or using an overhead
    hot line, but it would only be efficient at voltages much higher than would
    be safe.

    For energy storage capacitors, try:

    http://www.maxwell.com/ultracapacitors/index.asp

    From a previous post, here is a discussion of what to expect:

    Energy storage for the capacitors is based on 1/2*C*V^2, so your 210,000 uF
    25 V bank will store 65 J (watt-seconds). If you have 800 watts of motors
    (1 HP), the energy will power the vehicle for less than 0.1 seconds. They
    are most useful for quick energy dumps from dynamic braking, but you will
    need more than that to absorb the kinetic energy of a fast stop.
    Supercapacitors are available, such as Maxwell BPAP1200 – E270, which are
    1200 F at 2.7 V. Ten in series gives you 120 F at 27 volts, and energy
    storage of 43,000 W-Sec, or 50 seconds run time at 800 watts. They cost
    about $46 each.

    Some interesting high surge current capacitors are:

    http://www.sbelectronics.com/images/PDFs/Power_Ring_Options_0207.pdf

    Paul
     
  7. landotter

    landotter Guest

    They obviously haven't seen the proper way to do this...with a really
    big rubber band, like in the Swedish film, "The Apple War".

    http://en.wikipedia.org/wiki/The_Apple_War

    I wish I had screenies, but basically the bicycle guy in the film uses
    the rubber band to get to the bus stop really fast, and stretches it
    on the way home in the evening.
     
  8. A Muzi

    A Muzi Guest

    I still like my cable/pulley idea better.

    And we've all seen 'Zorba the Greek' with the wire guided logs.
     
  9. I've also seen that work OK.


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  10. Rich Grise

    Rich Grise Guest

    So, how did it work out? What did you finally end up with?

    Thanks,
    Rich
     
  11. ctyankee

    ctyankee Guest

    1200F @ 2.7 V -- that's not a capacitor! It's a rechargable hearing
    aid button cell <g>
     
  12. YD

    YD Guest

    Yeah, a big bunch of bungee cords can't be all that expensive. Needs a
    rather straight stretch of road, though.

    - YD.
     

  13. Use a pack mule. Its what they were created for.


    --
    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
     
  14. Do you have a link to more on those?
    Google's only references to "BPAP1200" are archived copies of your post.
     
  15. BobG

    BobG Guest

    Do you have a link to more on those?
    ==================================
    Search for Maxwell Technologies Boostcap
     
  16. Thankyou. Those look good.
     
  17. Maybe you should try with a fly-wheel first?
     
  18. Paul E. Schoen wrote:
    ....
    I would think the coolest method to use the potential energy of the wood
    to run the railway would be to burn it in a steam engine. :)

    Seriously though, I've seen small "railroads" in shopping malls that are
    run off 12V running through the rails. They're big enough to carry a
    bunch of kids so something similar should be able to lug a cartload or
    two of firewood. It doesn't have to be terribly efficient to be useful.
    Slow is also probably quite acceptable. If it saves you from having to
    make several trips then it can be quite slow and yet still faster than
    the alternative.

    You could even go all renewable on this and fit out solar panels on the
    top of the "engine" for this railroad. When the sun shines the thing
    will slowly work its way up the hill using whatever energy the panels
    produce. Add a stop switch at the top (of course) to keep it from going
    too far. So what it if takes a day or two to get there? It's not like
    you would have to be driving.

    Anthony
     
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