/diy/ - Do It Yourself

What is this generator for, charging your cellphone while you ride along? Charging a battery to power a lamp in your home or literally generating bicycles?
More specific criteria needed.

>>266131
The biggest tip I have is not using the biggest motor you can find as your generator. Otherwise, you may not even be able to pedal it. You will literally be pushing electrons when you pedal and the more you push the harder it will be. Maintaining 9amps at around 14v will be damn tough. But, maintaining 1amp at 14v will be a LOT easier. However, the less amps means the more time needed to charge a battery. you need to find out how many amps you can pedal out while maintaining the amount of volts required (14v for a 12v battery for instance.) Keep in mind that your motor will only tolerate X amount of amps for X amount of time. Push it too much and you'll burn it out.

One thing that many people overlook is adding a large flywheel to their design. This will aid you as you pedal. When you relax a little, the stored up energy in the flywheel will kick in for you and help you maintain speed. You'll find it easier to stop and start when the flywheel is still going. Essentially, it will smooth things out for you. The amount it helps you depends on the weight of the flywheel. The heavier the better, but the heavier it is the longer it takes to get up to speed. They help greatly in the long run, even when applied to a bicycle you use on the road.

Always match your own output power with the size of the battery you want to charge (6v, 12v, 48v, etc). The total amp hours of the battery array you have will determine how long you'll need to pedal to charge it (which is dependent on how many amps you can pedal out).

I see bicycle generators as something that is good for charging a battery array while getting a nice cardio workout for 30mins each day.

There's a few small errors in this pic, but it'll get you started in the right research direction.

Couldn't you just get an alternator and hook it up to the rear hub?

>>266208
Yes, but you'll need a few other things to help. Like a diode so that the battery doesn't start running the alternator as a battery.

>>266131
Not difficult to make, but unless you train to race bikes or something similar in the endurace athletics department, you'll only be able to maybe generate 100 watts sustained for any reasonable period of time.

>>266215
That is all you need to charge a 12v battery.

>>266215
14v at around 7.14 amps will be about 100watts. That is a near perfect range for a car battery for instance. But, it is a lot of work.

>>266230
Total amp-hour capacity of 12V battery/array being charged?

>>266235
It doesn't matter. It can be 30-1000. It is the amount of time you have to do it. It is was 1AH then it'd charge in no time at all. It all boils down to how much you use it versus the amount of time you have on hand to charge it up. 1000AH and you'll be doing this for a few days. lol

>>266234
Like I was saying.. if you're a trained cyclist, you could sustain 200-300 watts for 2-3 hours a day easily, but it wouldn't be much fun.

I'd think solar panels would be a better investment, and better use of your time as well. Ride a bike on the streets for fun and exercise, not stationary inside your house. I have a stationary trainer for my bike, and I only use it as a last resort (i.e. I'd rather ride in the cold and the dark than on the trainer if I can avoid it). Most people get burned out on pedaling inside quicker than they'd think.

>>266236
See, that's my point exactly. OP needs to take this into consideration. If his energy needs outweigh his ability to generate energy, then he's going to have a problem.

>>266131
OP, here's another consideration for you:
If you're going to spend any length of time sitting pedaling your generator, you're going to need airflow to keep yourself cool. I'm a trained cyclist, own and have used a stationary trainer, and believe you me you need a fan or something blowing air on you or you overheat quickly. Even outside you need a good steady breeze to keep you cool. Not trying to discourage you, but it's a reality.

>>266240
But, you can't put more amps into the array or you risk harming it. you'd need to build a bigger array with more volts in order to increase the amps you input past 9-10amps. Even with trickle chargers, they don't go past 10amps for a 12v array.

It'd be nice if the OP would return and give us more input. All this speculation is getting us no where.

>>266243
If you're using an automobile alternator, it's voltage regulated to start with. It would be fairly trivial to design a custom regulator for the alternator that would also current-limit the output to the battery/battery bank. It would also have the nice side-effect of not making the guy doing the pedaling work any harder than he needs to.

Side note: This system could also be designed with programmable current limiting and switched over to a load bank instead of charging batteries; instant cyclist power-training tool. You want to do intervals at a specific power? No problem, just dial it in and start pedaling.

Wow, Thanks for all the input.

OP here, I left after about 30 minutes of no replies.

I don't know much about electrical work, so If some one could explain the voltage and stuff to me I would be very thankful.

My plan was to charge some batteries (None in particular) and then use them to power various things with them (Think of a mobile wall socket).

I understand the need for a fly wheel, but I don't know what weight I should use. I was thinking using two 10 pound circular weights on the rear wheel on opposite sides to provide balance. Would 20 pounds be enough?

I was going to use the bike as often as I could.
Watching t.v.? Ride.
On the computer? Ride.
Reading a good book? Ride.
Then I was just going to keep all the charged batteries in a air tight container for when I would need them.

I had the idea a few hours before posting here, so its not well thought out.

>>266243
Also, (just as a side-bar discussion) lead-acid cells are very well-behaved and forgiving compared to pretty much any other type of rechargable cell; you really have to try hard to make one fail catastrophically, like completely short it out, or overcharge it for many hours. That, and the relatively low price, is why I think they still use them in automobiles.

>>266257
Give some examples of what sort of batteries you think you might be charging with this system.

Also, if you don't mind my asking, what is your motivation for wanting to do this? Why you want to do this may make a difference in what suggestions people make about implementing it.

>>266264
I suppose a battery that could hold a charge for a long time, and hold a large charge.

Mainly its to get some more exercise into my routine. But I had a bunch of trees fall and had my power out for about a week, I would like to be more prepared next time. The old trees through out the neighbor hood have all started to fall and have limbs fall off. Rotten trees are rotten.