Dia. Mag. Alternator

[z.monkey]

Aqua-VI

[z.monkey]

Mounting the motor plate here, and then adding the electric controls
for variable voltage and current...

[energia9]

Aqua-VI

i love your work Z Monkey, you are doing continous work on your idea, this is what overunity people should all do... keep up the nice work my friend....
what are your future goals?

peace

[z.monkey]

Thanks energia9,

I wish I had more time to devote to my projects.  Unfortunately I have many things to maintain, and over the past few weeks I have had to spend most of my time on my day job.  I am working towards making an actual product that I can sell, and turn that into a business.  Then maybe I can shed the day job.  This sounds simple enough, but it is a little harder than you might think.  The day job parallels my projects, so this is good in that the experience I gain there benefits my projects, and in my spare time at work I can work on my projects.  Slow progress is still good progress...

So, the Test Platform is coming along good.  I built a speed control board for controlling the voltage to the motor which is driving the DiaMag8 Alternator.  I want to overdrive the motor, so I built a 24 volt battery pack.  Then I can adjust the voltage going to the motor with the speed control board.  The motor is rated at 12 volts and I am wanting to take it up to about 18 volts to hit my target speed, which is 3600 RPM.  The label RPM is 2350 at 12 volts.  The pulley ratio is 1 to 2.3, so when the motor is turning 3600 RPM, the Alternator will be turning at 8280 RPM.

My initial design for the speed control didn't quite do what I wanted, and I had to rework it.  Originally I wanted a voltage control and a current control.  But the voltage regulator wasn't providing enough current and the current control just didn't work.  So I reconfigured the voltage regulator to drive the current regulator directly, and now only have one control.  At least now it works, schematic below.

Then there are the battery issues.  Big Sigh!  I had the D Cell battery holders and a bunch of D size batteries that I have used for projects in the past.  These batteries have been in the shop for years, and been used for various other projects and in flashlights, and all of them are mixed, unknown state.  So I get the battery pack put together, go test it, flip the switch and watch the voltage take a dive.  Uulgh...

There are 16 D cell batteries in the battery pack.  i had a thought to go buy new batteries.  I did test all the batteries and weeded out a few dead ones, but even then the battery pack would just barely turn the motor.  At this point I was really frustrated, and just walked away from it.  The next day I found a 12 volt 7 Ah sealed lead acid battery that I could use for testing.  So, after reconfiguring the battery I finally got the motor turning.  I am driving the motor directly with the lead acid battery because the voltage is too low to use with the speed control board.  Ultimately I want to replace the D cell batteries with new ones, and then I can use my speed control.

On to the next problem.  At 12 volts the motor is spinning at 2350 RPM, time the pulley ratio of 2.3, is 5400 RPM.  The alternator develops about 18.5 volts AC, open circuit.  This part is good.  The bad part is at this speed the centrifugal force on the aluminum rotor is causing it to stretch, and it is crashing into the stator.  This is extremely frustrating.  I regret using a soft metal on the stator.  I didn't have this problem before with the solid Neodymium rotors, they are very hard, and don't stretch much when taken to extreme RPMs.  So, now I have to take apart the DiaMag8, again, and try to increase the clearances around the rotor without damaging the windings.  Without the windings this would be relatively easy, just a mater of filing down the stator.  But doing this with the windings in there is kind of precarious.  Worst case scenario if I damage the windings is I will have to unwind and rewind the stator.  So, hopefully I can be intrepid enough to increase the clearances without damaging the windings...

So, getting there, very slowly...

[z.monkey]

Doh!

Found the problem...

I was all busy filing down the stator, and not making a difference.  I was looking at the rotor very carefully while it spun up.  I could see a definitive point where the rotor jumped up an hit the stator.  That's weird, why doesn't it expand gradually increase in diameter.  Why does it suddenly jump up like that.  Then I started inspecting the rotor.  The damn epoxy failed.  The magnet are loose, and when the centrifugal force exceeds the magnetic attraction the magnet pops out and hits the rotor, making a nasty grinding sound...

Forksocks!  This is exactly why I typically secure the magnets using hardware and not glue....

Aaargh!  Well, now I know.  The smooth surfaces of the metal make for a not so good bonding surface, and the epoxy was the 5 minute variety, so there is the very good chance the epoxy would fail.  Damnzit!  These radial segment have no other way to secure them.  No screw holes...

Looks like I'll have to use to industrial epoxy to get them to stick...

Well, at least I found the problem...

BTW, killed the Dremel Tool grinding the stator.  Yay!  Gotta buy another tool...