building electric scooter

If I am correct in decoding your question, no. You want to drive an alternator that charges the battery of the scooter, with the scooter? So, theoretically, you could go forever without any external power?

If you could find a 100% efficient alternator and motor, it still wouldn't work, unless you had zero resistance wiring, etc.

It's called a perpetual motion machine and it defies the laws of physics.

Soon, LynDoor™ Industries will announce a revolutionary scooter that harvests solar, wind, kinetic, thermal and methane _{(provided by the driver)} power that could travel to the moon and back. (If there was a road).

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"... a revolutionary scooter that harvests solar, wind, kinetic, thermal and methane..."

Huh? The memo I received says it is to be a wood-fired boiler. I must say your model sounds a bit more practical.

I believe your advice dispensed in the first two three paragraphs is sound. I advise the same.

Well,

That was more or less a test case for the back woods of Arkansas. I hear there is still a high demand for small copper boilers back yonder in the hills.

I was thinking along the lines of a Brew-N-Go scooter. Power the scooter and make a little "shine" on the run, so to speak.

Oh, I see...kind of a "mash" up?

"i was wondering is it possible to charge the battery via the (alternator/dynamo) to run a motor which can move the scooter wheel at low speed? is there any alternator or dynamo which can generate high output( just to run a motor at decent speed) at a low rpm?"

If you knew a LOT more about this subject, you would discover a way to utilize a "4 quadrant drive" and a PMDC motor. That way when the scooter was braking or going down hill, it would indeed charge the battery; it would act like a dynamo. You would still have a negative draw on the battery power when motoring and you cannot get more out of it that you put into it (unless you live in a place that is perpetually up hill from wherever you are going).

To be honest, this is a forum for electricians and electrical engineers in the building trade, we are not really your best resource for things like scooter designs. I suggest lurking in some electric vehicle forums, there are quite a few of them now.

May I suggest you to carry a foldable solar array with scooter and charge batteries when scooter is parked at home or office.