Best Alternator to Power 200W 24V/36V DC Motor With 30cm 15kg Flywheel Setup

A alternator will provide up to it's rated power, more or less. If you have a 80 amp alternator, you can draw up to 80 amps, for varying amounts of time.

You will have to apply about 140% of your draw to the shaft of the alternator to be able to provide that current. What are you planning on spinning the alternator with?

alternators do not "cog", but there is resistance based on draw, plus inefficiency (40% or so).

Thank God, I thought I was being totally stupid.

Hi Steve,
Here's the opportunity i think I see,

A bike (total 100kilos) 200watt motor within a 26inch back wheel {max legal speed on road 15mph}

Fly Wheel ? please look at the following YouTube video...Physics and Biking ///utube site cccstemclub.
NOW to me:
I think i know that an alternator when spun will produce a voltage potential dependent upon rate of turn. I think i know also that that potential can be stepped up/down with a transformer (although why one would want to change that potential from ac to dc eludes me)
NOW~ if all of that is true.... could one not attach a wheel to the alternator and then against that fly wheel it apply... and so in some way obtain the necessary power (current)
does that make sense?
LLOYD

200 watt bike motor is what you are driving, or using as an alternator? flywheels are not sources of energy, so drop that from the equation. what are you driving the alternator (or flywheel) with?

dc can't be transformed with a transformer, so you would need a dc - dc converter if you need to change voltage levels, but with a corresponding loss or gain in amps (wattage remains the same - inefficiency, about 10%).

Confused i am

Is not a spun flywheel a source of energy ...albeit a kinetic one ?

AND~ would it not provide , if connected to a small wheel around the shaft of an alternator a turning force within that alternator... and therefore a potential ?
I know there will be frictional loses .. but ?

As for the transformer question Are there not any ac motors AND does not the alternator itself put out an ac current ,therefore needing no transformer at all?

A spun flywheel is not a source of energy. What spins the flywheel, is the source of energy. A flywheel is a energy storage device, like a battery.

OK so obviously not making myself clear here.

So lets ask this instead ~ If i did in fact turn an alternator at any speed and fed that result into another alternator or the same sort... would the 2nd alternator not respond in direct proportion to whatever the 1st output was ?

no. you have friction/heat losses of about 40% or so.

ok thanks, now getting somewhere,

Would those losses be due to length between alternators (cable in other words) or just a result of the alternators construction.

OH YES~ the connection between the 2 would work, yes. Or have i misunderstood your answer ?

Every time we convert energy from one form to another we lose some. Torque to electricity in alternator, 40% gone. Your second alternator is now a motor because it is converting electrical energy into torque, another 40% loss. So you have lost 36% of the torque you started with.... Now what?

Hello again

Please disregard this question ~ Bad approach,
SORRY
Regards
lloyd.



Hello Everybody,
1st let me thank all those that responded to my last post AND ~ offer an apology to Chuck for not calling him.
I've been inundated with doubts Dear People
About what ? I'll leave till asked i think.

In the mean time may i ask for some Alternator advice, looking for the best one to match the following conditions.
Power a 200 watt dc motor 36volts i think but may be 24 volts (can't find the original pamphlet )
Problem~ Spinning the alternator is not it.... very little resistance with no load
BUT~ rather when spun and drawing the 200 watts what sort of resistance does its cogged shaft offer ?
AND~ T'were i to connect that cog to a 30cm15kilo fly wheel ... flying... just where would i set the alternators cog to get that 200 watt draw ?

Hope that's not nonsense ?
Regards
lloyd

Car alternators are not motors, so you must have a different alternator in mind. The losses are in the alternators / motors / conversion of electrical to mechanical and back again. You still have not answered the primary question. What is powering the original alternator? Something has to provide the torque to spin the flywheel etc.

Hello Steve,
Well blow me down, Thought i had really put my foot in it.
SO~ to answer you, Chuck i think answered the question, although i must say that 40% loss from 1st alternator then also a 40% loss on the 2nd one gives... to me an 80% loss total. BUT~ as I've said *I'm an idiot... when it comes to this/these questions.
ANYWAY~
Looking from my Id-otics point~ I believe there are alternators with +/- 1kilo weight/40amp rate AND~ thought WELL~ for that weight I might still, with all the losses, be left with about 10amps. AND that ,for what i had in mind... is perfect.
BUT~ .625amp... too little.
As for spinning the Flywheel, i know an answer like my legs will lead to all sorts of ridiculous suggestions from most, and in the main well founded BUT~please remember you don't know what I have in mind.
As for 2nd alternator as motor, i have seen it done on U tube though it did mean a modification of the second alternator in order to do it.
MY primary aim in asking about the alternators however, is founded upon my lack of understanding around ac/dc motors and the need to convert from one to the other, when I thought there are a/c motors SO~ way not just generate in ac and then transfer direct ac-ac motor.
AS for what i want to do~I can already do it~just with magnets alone. BUT~ since i can, i thought i may be able to utilize that ability in an Electrical capacity... and so here i ma on this forum trying to understand some of the fundamentals of generating electricity.
REGARDS

LLOYD

I suspected this is where you were going. You are under the misconception that magnets are a power source. NO, you cannot produce work with magnets. Work must go into the spinning of magnets, to produce work. Magnets themselves will not do the job. This is a fundamental you need to learn, or your whole project is doomed. There's a lot of lies on youtube, either because the person is clueless, or deliberately misleading you.

YES repeat YES ~ Steve you are correct, but I didn't say magnets were *A POWER SOURCE*~ I seem to have failed however to say that *THEY HAVE A POTENTIAL POWER* held within them, needing work yes and as I've just said, that side of my *POWERING REQUIREMENTS* is already sorted.
In other words: by pumping my legs I can with magnets multiply the result. and am currently putting said contraption to~ trails.
What interests me is using those magnets after I've proven i can spin them >>> relatively easily.

FOR EXAMPLE:
If i had a coil {enamel coated} wrapped around an air cored tube, and filled with Ferro fluid~ perhaps also with Iron fillings therein.... what would be the result.
I know it aught to be a simple one to test BUT~ I'm unemployed and all my money has gone into magnets leaving non for the purchase of the wires needed in order to test, let alone answering the questions of just what thickness of wire i would be best testing with.

Ah, ok, so you are the power source. Now we are getting somewhere.

The human body can maintain an output of about 100 watts for periods of time. Higher wattages for short bursts.

The magnets contain no potential power. You are the potential power. The magnets are simply part of the conversion process from mechanical to electrical energy. If you have purchased magnets, then you are not discussing car alternators, you are talking about building your own permanent magnet generator? 60 amps are not possible at 12v from the human body. 10 amps are. A car alternator requires a few thousand rpm to provide this, and the field coils consume most of what the human body can produce, so a dc permanent magnet is best. 30-90vdc motors found in treadmills to electric lawnmowers are useful.

THANKS STEVE :
BUT~Would you mind if ... that potential / not potential question be put aside in your next response to me ?

OF MORE INTEREST ~ is the question relating to your opinion/experience regarding the use of Ferro Fluid *within* a turn of conducting wire ... also well as , if you know~ the additional idea of including an x amount of Iron Fillings within that liquid Ferro Fluid ?
AND THEN~ applied a current... to that coil ?
REGARDS

LLOYD