bicycle generator project

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windozeuser

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Hey guys,

I feel like doing a project to get in shape in the summer, and I'm thinking about a bicycle generator that can be used to power a laptop. The generator output would be tied to a laptop's car adapter power supply. I just want to know if this is even possible, can I generate the power necessary to power a standard laptop? What is the best way to approach this?

I'm assuming that the laptop battery is an absolute must to have to keep the generator "filtered" when there is no activity or lower activity.
 
If your laptop uses 50W then you will need to pedal extremely hard.
A headlight for a bike is only about 2W and you can feel the drag from its generator.
 
Just use a standard car alternator.

You will need a small 12 V battery to get the alternator "started". If you don't have one, there is no field current, so no magnetic field, so no electricity.

I would cut the fan fins off, as you probably won't overheat the alternator even without them, because you are not going to be able to produce the power that an alternator produces at peak, and you will have it in a room at 25 deg C or less and not at 70 deg C that they have to work at under the bonnet (hood in USA speak)

Alternator work best above about 4000 rpm, although you might get away with 2000 rpm.

You want a roller about 4 cm diameter on the car altenator, with the bike wheel resting on that.

20 mph will give you the power to run a laptop, but you will notice that if you are actually travelling. If you intend to run the bike and laptop when stationary it will be fine.
 
audioguru said:
If your laptop uses 50W then you will need to pedal extremely hard.
A headlight for a bike is only about 2W and you can feel the drag from its generator.
Click to expand...

That is more because the bike generators are so bad. Most people cycling can produce 100 - 200 W for long periods of time. Professional cyclists produce over 300 W with peaks over 1 kW.

2W is about 1 ounce of drag at 20 mph.
 
Attach a car alternator to a bicycle??
Use a laptop computer while riding a bicycle??
Now I have heard every weird thing.
 
It may make sense to charge a laptop while riding but generating the power to run one in real time would be too much effort.

I would look into the generator in the hub concept like


The problem is that they are only 6V.
 
3v0 said:
It may make sense to charge a laptop while riding but generating the power to run one in real time would be too much effort.

I would look into the generator in the hub concept like


The problem is that they are only 6V.
Click to expand...


WOA, $300 Bux for a dynamo? U gotta be F$@%^ kidding me!
 
I like the idea of a car alternator hooked up to the bike. Mount a 24-inch pulley concentric to the front (or rear) wheel and slip a v-belt over it and onto the alternator's pulley. That should get the speed up a bit. Making the bracket for the alternator may be a bit of a problem, but that's what this is all about anyway -- solving problems.

Mount the laptop on the handlebars. With a small amount of circuitry, you can measure the frequency of the alternator output and convert this into speed (MPH or kMPH) for display on your laptop. Of course, a crash can be pretty costly here. You might want to be using your cell phone while you ride to keep in contact with friends so they'll always know your status. Since you have all that electrical power available, a flat-screen TV would be a good addition to your "dashboard" electronics. And you might as well upgrade to a full-bore automotive quartz-halogen headlight rather than that dinky little LED model. Tail lights and turn signals could be provided. Hang a dome light from a stalk so you can see your keyboard while night riding.

Dean
 
I had to purchase a 140 watt inverter to power my laptop (nothing special) based on AC power supply current requirements indicated. I do not know the average power consumption.

There are some references that describe the horsepower levels that a human can achieve. One of the references suggests that a "heathy human" can deliver to pedals about 0.28 hp for one hour - only 0.1 for 8 hours. A "first class athelete" can deliver 0.44 hp for an hour and 0.4 for 8 hours. Let's use the "heathy human" for one hour as a place to begin.

0.28 hp is 209 watts - that's at the pedals. Your bicycle isn't without friction nor will the mechanism to deliver the power to the generator or alternator be free of losses. Once you get to the shaft of the generator/alternator there are additional losses.

Based on this it would seem that a very efficient bicycle mechanical system coupled to an efficient generator or alternator might power a laptop with modest power demands - or possibly extend the working period of a laptop battery.
 
Frosty_47 said:
WOA, $300 Bux for a dynamo? U gotta be F$@%^ kidding me!
Click to expand...

It seems like a lot but people who are serious about cycling are buying them.
 
Thanks a lot everyone, I like the car alternator idea it's worth a shot I'm so bored in college. Also, dean I detect humor/sarcasm in your post
 
Generally it's said that a bycycle driven generator can provide about 60-100W of output - but that's hard work.
 
just buy a bike dynamo. they are still availible these days rite??if you really want to charge your laptop battery in summer than it would be a better idea to use solar panels instead. wasy and i guess a bit cheaper than a car alternator and components.
 
Once at the gym, they had one of the bikes taken apart for repairs. Inside was a generator connected to a big honkin power resistor. All that dissapated energy could have been put to good use

EDIT: Didn't notice the date, until I saw Hero has posted, then I knew it was old
 
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