Light weight flywheel project

[cywelchjr]

Well it seems as though I've provoked quite a discussion.Thank You for all the responses.It is my intention to balance the rotor and I will weigh both parts to see what the difference is and post the results.I'll also slap an amp meter on it to see how much charging ability is lost. Terry

It might be hard to quantify any difference in charging capacity unless you have something that can force the system to put out it's maximum (think an artificial load). It can certainly be done, but may require equipment you don't have available to you.

PS. part of the load of an alternator is also load based, as the more current is drawn the more it resists rotation. This in most alternators is the majority of the resistance to rotation, I don't know if that is the same with these systems that just stir the field rather than rotate it.

[crazy steve]

It might be hard to quantify any difference in charging capacity unless you have something that can force the system to put out it's maximum (think an artificial load). It can certainly be done, but may require equipment you don't have available to you.

PS. part of the load of an alternator is also load based, as the more current is drawn the more it resists rotation. This in most alternators is the majority of the resistance to rotation, I don't know if that is the same with these systems that just stir the field rather than rotate it.

Yep, the only way to tell what you would lose would be with a charging system load tester; most parts houses have those, just make sure they don't put more load on than what the diodes are good for...

Your PS brings up an interesting point; I would think that this would be the same as a 'conventional' alternator of the same output as you're still doing the 'work' of converting mechanical energy to electrical energy, but maybe not...

[cywelchjr]

Yep, the only way to tell what you would lose would be with a charging system load tester; most parts houses have those, just make sure they don't put more load on than what the diodes are good for...

Your PS brings up an interesting point; I would think that this would be the same as a 'conventional' alternator of the same output as you're still doing the 'work' of converting mechanical energy to electrical energy, but maybe not...

That was what I was thinking, but the stirring just might be more efficient from a standpoint of resistance to rotation since I'm not sure what the movement is of the magnetic field. If it's rotational in nature (not full circle of course but back and forth) I would expect the same drag as on a more conventional system, but if it's (as I think it might be) a movement in and out from the center, that may well provide less drag, making it more efficient in that way (even though from other factors it's less efficient).

[crazy steve]

That was what I was thinking, but the stirring just might be more efficient from a standpoint of resistance to rotation since I'm not sure what the movement is of the magnetic field. If it's rotational in nature (not full circle of course but back and forth) I would expect the same drag as on a more conventional system, but if it's (as I think it might be) a movement in and out from the center, that may well provide less drag, making it more efficient in that way (even though from other factors it's less efficient).

Thinking about it more, I doubt if it's rotational at all. You've got a steady magnetic field (the stator) that's putting out flux that goes into the poles on the rotor. So the rotor see the same flux amount all the time. But as you move the rotor poles past the field pole windings, as the poles first come into 'range' the flux starts small, building as the rotor pole gets to being centered on the field pole, then dropping as it passes. Sort of a 'simulated' AC, so it's acting more like a transformer rather than a true alternator.

But you still have 746 watts = 1 hp (and that hasn't been repealed that I know of! ), so you would still need .39 hp to produce 290 watts (20 amps @ 14.5v), not including any losses.

[cywelchjr]

Thinking about it more, I doubt if it's rotational at all. You've got a steady magnetic field (the stator) that's putting out flux that goes into the poles on the rotor. So the rotor see the same flux amount all the time. But as you move the rotor poles past the field pole windings, as the poles first come into 'range' the flux starts small, building as the rotor pole gets to being centered on the field pole, then dropping as it passes. Sort of a 'simulated' AC, so it's acting more like a transformer rather than a true alternator.

But you still have 746 watts = 1 hp (and that hasn't been repealed that I know of! ), so you would still need .39 hp to produce 290 watts (20 amps @ 14.5v), not including any losses.

Ahh, but there's the rub. It's all about efficiency, and I'm not sure which method from the point of drag to the rotating mass, is more efficient and gives more energy for that drag with less as heat. Maybe there is no difference, but maybe there is. I think it would be very hard to quantify. That said, I think that all the lightening of that rotor you may do is going to be insignificant to the performance of the engine, but it might impair the operation of the alternator.

[T99Ford]

But in addition to allowing the engine to rev more quickly, the engine will also brake more quickly, due to the loss of rotational mass. Both of these together are very desirable in a road racing bike. Not sure how much on the xs, but there was better than a pound to be gained off the one on my VTR.

[T99Ford]

T-Dub,
Any more progress on this? I am curious to see what, if any, performance change you have noticed.