charging car batteries using bicycle dynamo concept

Discussion in 'The Projects Forum' started by mustrule, Aug 30, 2012.

  1. mustrule

    Thread Starter New Member

    Aug 30, 2012
    2
    0
    hi everyone,

    i'm new here.

    i have some project with friends which need to using electrical at placed that don't have any supplies. soo we can only use car batt to do so.

    is anyone can help me how can i use the bicycle dynamo concept to charging the batt so i don't need to charge it other place ? and how can make built it.

    tq.
     
    Last edited: Aug 30, 2012
  2. wayneh

    Expert

    Sep 9, 2010
    12,120
    3,046
    Are you starting with anything? I mean, do you already have a dynamo or similar parts?

    The traditional bicycle "bottle" dynamo is designed for 6V, I believe, and is not terribly efficient. There are superior designs now that are built into a wheel hub. They are much more efficient and the drag on the pedaler is mostly the electrical load, not just friction.

    Just FYI, a casual rider can only produce about 75W at the wheels for a sustained time (2 hours or more). This is about 12 mph on a good bike. And, the process of charging and discharging a battery is only about 50% efficient.

    My point is, you may be disappointed at how hard it is to make this all work the way you want it to. What do you want to power?
     
    mustrule likes this.
  3. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    A car battery is a very poor choice for a deep-cycle application. Car batteries are designed to output very high current (perhaps 400A or more) for a short period of time, and then must be immediately recharged. Allowing a car battery to become discharged for even short periods of time will drastically reduce their service life.

    If the application is other than automotive, you need a deep-cycle battery. Even deep-cycle batteries will have a short life if they are discharged past ~75% of full. People frequently run batteries down to 50% charge, and they don't realize that they reduce the battery by 2/3 of normal expected service life.
     
    mustrule likes this.
  4. cork_ie

    Member

    Oct 8, 2011
    348
    58
    Bicycle dynamos typically generate 3VAC or 6VAC the former being the most common. Watts output are generally about 5Watt and even at that you would notice the load on the bicycle while cycling as there are friction losses etc.

    To charge a 12V battery automotive or deep cycle you will have to

    1) Do an awful lot of cycling
    2) Use a transformer and pass the current through a rectifier and some type of regulator to get 14.5 V approx to charge the battery.
    Alternately rectify the voltage and use a buck boost converter to get 14.5 V DC.

    The results are likely to be extremely disappointing and a solar panel or wind generator is likely to be far more`suitable
     
    mustrule likes this.
  5. wayneh

    Expert

    Sep 9, 2010
    12,120
    3,046
    The OP was warned about this in #2 and hasn't been heard of since.

    The worst part of this plan is that, overall, it converts human food into electricity via a series of very lossy steps. Every watt-hour delivered to the the ultimate load requires about 8 watt-hours of food energy. (Factor of 2 in the battery charging process times a factor of 4 for human pedaling efficiency.) A watt-hour is roughly 1 (kilo) calorie. (1 W•hr = 860 calories).

    This is why steam engines revolutionized the world. You can get power from cheap fuels instead of food. An old fashioned steam engine would help the OP more than a modified bicycle. ;)
     
    mustrule likes this.
  6. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    A guy tried to use a computer fan as a generator on his bicycle to charge some Ni-Cad cells to light some LEDs at night. After pedalling fast for one hour the battery charge lighted the LEDs for only ten seconds.

    He was told that the computer fan was too small to generate enough current and a huge fan must be used which will have as much drag as pulling an open umbrella around behind him.

    Human food converted into electricity?
    If there are one thousand people pedalling and driving generators then how will they receive their millions of bowls of rice?
    It would be more efficient to use the rice to make rice wine, distill it into alcohol then burn it to drive a steam engine if the thousand people don't drink all the rice wine.:)
     
    mustrule likes this.
  7. cork_ie

    Member

    Oct 8, 2011
    348
    58
    I totally agree.

    I remember reading somewhere that the average adult male uses 110 Watts just to exist , any little bit of exercise will obviously consume more.
     
    mustrule likes this.
  8. mustrule

    Thread Starter New Member

    Aug 30, 2012
    2
    0
    tq

    how about if i use similar method by using water wheel? is it possible to generate enough energy to charging the batteries?

    is there any differences?

    if possible, how can i built it and what it's need to built it?

    tq.
     
  9. cork_ie

    Member

    Oct 8, 2011
    348
    58
    Google "Turgo Turbine" - they are cheap & simple and surprisingly efficient.

    A lot depends on the flow and head.
     
    mustrule likes this.
  10. JMW

    Member

    Nov 21, 2011
    88
    8
    The problem is you are considering adults. I've known a couple of 5 year olds whose output rivals a small nuke. Find a 6th or 7th grade teacher and ask if she knows of any children with ADD. Get a couple of these and you should be able to run the TV and AC.
    As an alternative, I'm working on incorporating fuel cells in underwear. A couple of kilos of brussels sprouts should be able to power a several homes.
     
    mustrule likes this.
  11. wayneh

    Expert

    Sep 9, 2010
    12,120
    3,046
    Now that's thinking outside of the boxers! :p

    If you need electricity, the strategy for making it comes down to what you have on hand and what your skills are. Catalytic underpants might be handy if you have gassy 6th graders. If you live on top a windy hill, perhaps a windmill. In the sunny desert, solar panels look pretty good. Powering a small radio in the gym using the energy from the exercise bikes makes sense. Live by a waterfall? Hydroelectric becomes a good option.

    The key to making a good choice and avoiding disappointment is to consider the complete end-to-end process and efficiency losses at every step. For instance if you need 1HP continuous, then a single bike rider is not going to do it.
    steam-powered bike!
    [​IMG]
     
  12. electriccircuit0101

    New Member

    Sep 3, 2012
    1
    0
    A friend of mine who studied electronics at university learnt about charging batteries using the bicycle dynamo concept in his last module. He told me that the dynamo uses rotating coils of wire and magnetic fields to convert the rotation into electrical current. I watched him fully charge a hawker battery for a railway vehicle using this concept. It was awesome and I couldn't believe it. I felt like I was back at school watching the science teacher carrying out an experiment! The battery he charged was actually bought from - <snip>
     
    Last edited by a moderator: Sep 5, 2012
Loading...