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Alternative power

  1. Jul 23, 2004 #1
    well i have a very genuine problem and if someone could help it will be very usefull
    The power supply in our area is very erratic with long powercuts and makes life difficlut for me to study.
    well if someone could advice some cheap alternative power source i could develop to power fan and tube light it wil be very nice.Solar power is ruled out as panels costa bomb some innovative idea to light cfl bulbs small fans will be apreciated.
  2. jcsd
  3. Jul 23, 2004 #2


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    How about a gasoline or diesel generator?

    - Warren
  4. Jul 23, 2004 #3

    Ivan Seeking

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    You could run off 12 VDC using a car battery, or even two batteries in parallel. When power comes back run a battery charger. I don't think you will find a cheaper approach that has any lasting power. A large, lead acid car battery can supply 250 amp-hours or more. Just make sure that you don't run the battery in the house. Dangerous and toxic fumes are generated in the battery during use and charging. On very rare occasion the battery can even explode so never treat this as an indoor use item. You should be able to set this up through WalMart for less than $100.00.

    There are two key numbers to consider: How much power do you need and for how long? This will tell you what you need, or what will work. If your power needs are low enough you might look into other rechargable batteries, but again the price will dictate otherwise, I think. For comparison, at 3.8 amp-hours, my laptop battery costs three times what a car battery does. If your energy needs are low enough, you should be able to pick up a small car battery for as little as $30.00.
    Last edited: Jul 23, 2004
  5. Jul 23, 2004 #4

    Well actually i am using 150 amperes hour 12 volt battery and an inverter but they ar eless effective as after 3-4 hours they get discharged also my battery is liitle old so backup is not as good.
    Well i had a an idea earlier if a take a dynamo and put it at back of bicyle will mechanical power be converted to electrical power wnough to power few things what parameter will i hasve to see? Or are there some good sites on net about it.
    Well i had read somewhere on net about some cell developed by using sugarcubes and bacterial acion of e-coli on sugar cube producing enough to power 40 watt bulb for 8 hours is it possible?
    Please advice
    Anyway thanx for help
  6. Jul 24, 2004 #5


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    I believe you guys are mistaken on the Ah capacity or prices for an automotive battery. Last I checked, a regular car battery did 60Ah or less until you get to some very large batteries...

    As far as bike power is concerned, you should google some more info and search on this site. IIRC, you can expect maybe 150W continous power if you're in quite good shape or 300W if you're in great shape and for maybe an hour. Low consumption lighting like LEDs would be a great way to extend capacity by reducing usage of any storage option.

  7. Jul 24, 2004 #6

    Ivan Seeking

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    Whoops!!! You are correct sir. Thanks for catching that.

    http://www.exideworld.com/products/automotive/orbital_xcd_specs.html [Broken]

    Typical auto battery at 50 AH. I usually work with large equipment and apparently was citing typical values that I have encountered in that arena. Sorry about that.

    As for the cycle power, I have quite a bit of experience in this area, just by chance. Its a long story but I did a two year project that dealt with this specifially. Your numbers sound pretty good but maybe a little generous. The average full grown male can produce about 100 watts constantly. The difficulty increases drastically with increased load. In my experience, which includes hours of observations of exactly this, strangely enough, most people could not produce three hundred watts for an hour; I would say more like 200 watts for the vast majority of even athletic people.

    An interesting note: An olympic athlete can produce about 1000 Watts for three seconds. That's the highest human output ever measured on a cycle.
    Last edited by a moderator: May 1, 2017
  8. Jul 24, 2004 #7

    Ivan Seeking

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    Oh yes, it depends greatly on the length of the pedal arm and the gear ratios used. We are much more efficient at high torque, low speed motion, than we are at low torque, high speed motion. given an ideal design the numbers given by Cliff may be closer to the mark than I would expect from a typical cycle.
    Last edited: Jul 24, 2004
  9. Jul 24, 2004 #8

    Ivan Seeking

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    That's the ticket. The power demand drops like a rock. Compared to the alternatives, this wouldn't be very expensive.

    Oh yes, as for the cycle ambuj123, what good is a fan if you produce the power? I think you are chasing your tail on that one. :biggrin:
  10. Jul 25, 2004 #9
    Well actually
    cycle power which i am talking could maybe able to light bulb or charge battery
    while battery b150 ah is special one about four time larger than car battery having 25 plates
    Cheers Physicsforums
    thanx for replies
  11. Jul 27, 2004 #10


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    I swear the trick to pedal power would be to have a huge flywheel setup, get that sucker spinning as fast as possible, then let it do the work.

    as for led lights, batterys, and all sorts of electrical goodies, you must check out www.sciplus.com

    I think i stumbled on it on one of the ads above.
  12. Jul 29, 2004 #11


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    A flywheel is no more efficient at storing power than a generator and battery. And mechanically, its a lot tougher because the energy comes from constant acceleration - so its drive motor (person) must be equipped with a continuously variable transmission.
  13. Jul 29, 2004 #12
  14. Sep 18, 2004 #13
    Here is a framework fabricated to enable a small gasoline engine to twist an automotive alternator. The output of this unit into a 12-volt battery is roughly 35A. Using a five horsepower engine with 4 to 6 inch pulley allows for running at a lower RPM (important if you enjoy silence as much as I do). It is possible to be very creative with exhaust and fuel systems on such a rig, not to mention remote start. Many alternators are capable of producing in excess of 100 amps, provided you have enough engine, so scaling to suit individual needs is a delight. Also, availability of parts generally is not an issue. I don’t recommend a direct drive as the diode connections will then need to be altered due to alternator revolving counter to normal, but it is possible for the determined (have another photo of such, but too lazy to scan it).

    Good luck !

    Attached Files:

  15. Sep 25, 2004 #14
    You want cheap? You GOT cheap!


    Below is a photo of a human powered electric generator. I took the liberty of whiting out much of the photo so as to make the important pieces stand out better. This contraption can output over 10A into a 12V battery, but you will need strong legs if you are to maintain that level. More realistically would be a figure of approximately half that, or even less.
    Central to all this is that virtually every component was scrounged. If you really want to dabble with alternate power sources it helps to be a good scrounger and fabricator. For the inexperienced, allow me to detail most of the components you’re viewing; the large pulley was from a broken cement mixer, and the bearing it is welded to (difficult to see it, but a vital component here) came from a tractor’s water pump that had begun to leak around the seal (but still plenty good for this purpose). The middle pulleys are from a junk automobile engine and a small engine (they are welded together). The small pulley on the PM motor was special (Drilled ½” through some metal stock, drilled and tapped for an Allen head screw, then put on the motor itself, secured in a vice, powered on and cut the belt channel). The motor has been secured in a piece of 2x6. The pedals are 2x4, greased to spin on ½” bolts. Much use of bolts was used, both for spinning things on as well as for securing brackets. Note the two identical brackets used to hold tension on one of the belts (it was a quick fix for shortage of material, haha). Adjustable seat height was another feature of this rig.
    Well, hopefully this might serve as inspiration for your own creation by showing that a little imagination can often go a long way.

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