I need help buiding an alternator for a Baja!!!

Ok so my buddy asked me to help him build a alternator for his 1/5th scale Baja 5B.

If the drivetrain spins a brushless moter, can rectifying diodes be used to generate DC current?
Then the current it is put through a filter cap and then trough a voltage regulator to get a constant voltage regardless of how fast the brushless is spinning.

This is what I'm talking about:


The VR I have can accept 5.5-40v.

How is the brushless moter wired? Is the black wire a common ground between the two coils?
In which case this setup will work.


Does anyone know how brushless moters are wired? Because that will determine the schematic. We don't want to use a brushed moter if we can avoid it.

Thanx
-Tony

Re: I need help buiding an alternator for a Baja!!

I'm not sure a brushless motor is efficient for your purpose. A brushless motor relies on a series of stationary coils to turn either a metal shell(outrunner) or a central shaft(inrunner) lined with small magnets... I doubt those tiny magnets are efficient at producing power. Also, anytime you use a motor as a generator, it will almost always be AC...

As for your "rectifier", why not build a bridge rectifier and utilize the whole wave instead of chopping half of it away?

Re: I need help buiding an alternator for a Baja!!

digital_blue said:

I'm not sure a brushless motor is efficient for your purpose. A brushless motor relies on a series of stationary coils to turn either a metal shell(outrunner) or a central shaft(inrunner) lined with small magnets... I doubt those tiny magnets are efficient at producing power. Also, anytime you use a motor as a generator, it will almost always be AC...

As for your "rectifier", why not build a bridge rectifier and utilize the whole wave instead of chopping half of it away?

Click to expand...

Well a bridge rectifier is just a matrix of 4 single rectifying diodes, that would work for a brushed moter. However, since this is brushless it works a little differently. That will filter the AC into DC. Then the pulsed DC is run through a large capacitor to smooth the voltage.

You're right though it will have to be a large brushless to provide enough current. I have seen it done before. It's especially popular with gas helicopters.

I know there are many little coils in a brushless, but there are only 3 wires so wouldn't that mean that there is a common ground and two +? In which case the 2nd schematic will work.

I guess worst case scenario we could use brushed moter but that might be too much of a load on the main moter. :-/

-Tony