Alternator power

[go4it]

I just finished reading the link from an earlier post about using a rheostat to control the output of a GM Alternator and I wondered how much power it took to activate the alternator.  Would it be possible to power these coils with a smaller PMA driven off the same shaft thereby allowing the windmill to get some speed before the alternator started to load the system.  If that was the case then you should be able to have a windmill that operated at a fairly constant speed with the PMA powering the coils in the alternator.

Does this make sense or am I out in left field.

[Opera House]

I think the issue typically is that an alternator field can draw up to 4A and why use power just to create a magnetic field.

[mlz]

I have used a simular method, however I just stuck two magnets to the rotor and ran them by some coils.  That would then open a junction to allow current through.  Worked well.  Personally, I would just build a PMG alternator, or pick up a cheap induction motor and use that.  Car alternators just don't work very well for this application.

[Jerry]

I agree with Mike. I've refited GM car alts with 14 NEO magnets and was able to get 337 watts at 30 mph but at the same time I was able to get 650 watts from a converted garbage disposal motor with only 4 $5 magnets.

                          JK TAS Jerry

[Opera House]

I just picked up a GE ECM 1/2 HP furnace blower motor for $5.   There is nothing easier than just slapping a full wave bridge on this baby.  These started being installed in the early 90's and the failing electronics are starting to make these common in the dumpsters of the HVAC guys.

[Paulm]

You must be talking about after digging out the winding connections ?

[johnlm]

To Opera House,

Very interesting info on the GE motors.  I just looked at these on the GE web site to see what you were talking about.  These things are a ready built polyphase PMG waiting for someone to utilize there new life after serving their first life as a variable speed motor.  Al one has to do is tear out the electronic speed control bring out the winding leads.  As my Russian friend would say "SWEET".

Johnlm

[Jerry]

Hi Paul

These motors are perminet magnet motors. They allready have ceramic magnets and a set of 3 phase wires allready comeing out of the case. Just hook up diodes and you have a PMA.

However the problem is they are best suited for 48 volt app.

But the coils can be reasigned for 12 volt use.

Here are some wattage reading I got at 12 volt and 48 volt in the stock wireing mode.

GE ECM mph wind and power test.

12. volt  15mph 33 watts,   20mph 104 watts,   25mph 110 watts
    
48. volt  15mph 120 watts   20mph 200 watts,   25mph 250 watts
    
    

As you can see from these #s a GE ECM motor is best suited for hi voltage in the stock wireing form but this can be changed.

I discribe the changes latter. I'm off to work now.

               JK TAS Jerry

[Jerry]

The plains for the GE ECM motor. These motors have 18 coils.

I think there are 3 sets of 6 coils wired in siries and then wired star for 3 phase.

Since this is set at too high of voltage for 12 volt use my intention is to wire this unit 9 phase star. I'll wire a coil exactly accross from each other in siries. This will make 9 sets of 2 coils wired in siries. These 9 set are out of phase with each other.

The end result will be voltage much closer to 12v than 48 and many times the amperage. I did this with the F&P with 21 phase and it hit around 1,000 watts.

This GE ECM motor is rated 12.5 amps at 120 vac this = 1500 watts. So we know there is some potential there.

All of my GE ECMs are flying right now in a 48 volt system. I'll be bringing one down in a week or so. I'll be doing the 9 phase thing then.

I'll report the results when done.

                           JK TAS Jerry

[johnlm]

Jerry,

wouldn't it be easier to just wire it in a Delta configuration with the leads that are already coming out without going in and getting into the coils?  It would accomplish almost the same result as rewiring it the way you talked about.

Johnlm

[ghurd]

Hi Jerry and everyone,

Would the stock wiring be good for low wind speeds (faster cut in) on a 12 volt system?

Seems like at say 7 mph, the stock wiring would be to charging voltage for 12v but still below 48v.  Or a rewire for 12v would also still be under charging voltage.

I expect some stalling issues with the blades I've got

A day with 20 mph gusts is big wind around here. We're going to try to get what we can in the 5-10mph area. Anything is better than nothing.

Maybe I'm way off track here.

Thanks

G-

[Jerry]

Hi G

The stock wireing will give you a very small amount of charging in low will speeds. Yest stalling would be a problem. A larger blade will help this at the reduction in rpm.

These motor do load a blade down even at 48v.

                     JK TAS Jerry