1HP 3P Motor Conversion Part IV

[valterra]

I'll detail later (when I have time) how I came upon these numbers.  They are all approximate, but should be pretty close.

For the battery test, I know I need to do it with the battery relatively the same voltage.  Flux was right (of course) that the voltage races up quickly.

All are Low Volt Jerry Rig

VOC Tests:

 240 RPM - 16.5V

 330 RPM - 21V

 570 RPM - 75V

 810 RPM - 111V

Battery Tests:

 240 RPM - 12.3V 0.450A

 360 RPM - 13.6V 4.13A

 510 RPM - 14.9V 9.23A

Should I do the battery test again trying to regulate the voltage?  It won't be today.  :-P

[Flux]

I can't make any sense of your open circuit volts.

The first 2 and last 2 make sense individually but the first group doesn't make sense with the second group.

If 240 and330 are right then the other 2 speeds ought to be about double. If that was done on a lathe was there a 2 speed motor involved?

Until we sort that I am reluctant to take any notice of the battery figures.

Flux

[valterra]

This was my own test, and I will calculate again.  I used a "fairly" scientific method.  The bit that I drove the motor with was flat.  Once it got up to speed, I held a metal piece to it and it made a very distinct tick-tack sound.  2 of them per rotation.  

I videotaped the whole thing (voltmeters).  Then I took the sound of the video into a sound editing software where you can clearly see each tick.

http://picasaweb.google.com/jehmobile/SoundProgram?authkey=Y7cqUa1dGCk#

I highlighted 1 second of sound.

Counted the ticks.

Multiplied by 30 (remember 2 per second) to get the RPM.

Then replayed the video portion at the same spot and read the voltmeter for a few seconds.

Audio sample lengths were only 1 or 2 seconds.

I will RE-test with longer sample times to make sure I get more accurate numbers, like 10-20 seconds each.

Throw out the highest number.  The sound was muddled anyway.

[valterra]

Tomorrow I will try to run the motor on my buddy's lathe.  That should present very rock solid numbers.

I don't want to waste your time, Flux.  :-)  I was just eager to get some numbers out there.

[Ungrounded Lightning Rod]

There's an almost exact 2 to 1 factor between the first two and the second two open circuit measurements.  The first two are about .064 and .069 volts/RPM and the second about .137 and .132 volts/RPM.

Did you perhaps measure some with two coils in series, or forget to divide something by 2, change the sample length, or multiply by 60 rather than 30 sometimes?

Using the first figure (.06875 v/RPM) and assuming SIX diode drops in series (3.6v) the three RMP vs. V and A measurements make some sense.  They correspond to 1.33, 1.82, and 1.79 ohms of coil resistance, respectively.  (The low one is probably off because the diode E/I curve is an exponential rather than a hockey stick.)

How do you have these hooked up?  You should have only two diodes in series, not six.  (Or I could be off in my guess of 6.)

[valterra]

ULR:

I have it hooked up Low Volt Jerry to 3 bridges.  Bridges are hooked up in parallel and DC Voltage is measured on the common wires.

I can provide more detail if necessary.  

Listening to longer samples, I got slightly (15-20% variance) numbers.  So I will hook to the lathe tomorrow (hopefully) and return some proper numbers.  But these should be close.  All except the 111v RPM.  The sound is muffled on that one.  

If you'd like a copy of the video / audio file(s), feel free to email me at:

jehmobile at gmail dot com

[Jerry]

I've never done a laithe test on the Garbogen.

It is a 1 hp motor conversion. I havn't had a Garbogen PMA for a while so I through one together.

This PMA is a 2 phase. It was a single phase motor.

It's set up for 12 volt.  I did a laithe test on this one at 430 rpm.

No load at 430 rpm the fluke says 24.07 volts dc.

I hope to do more testing this week.

In the real world bench test I use an infered RPM meter, 6 each 220 amp/hr golf cart batteries configured as 12 volt, 2.5 HP varyable speed 100 lb DC motor as prime driver, 5 KW varyac to control input voltage to the fullwave bridge and 4,000 UF/400 volt cap bank that supplies dc to the motor, 2 infered thermometers, a Fluke true RMS volt meter, a realy nice 60 amp analog amp meter, a 400 amp digital amp meter.

I wish we had your PMA here for some good bench testing.

I'll be testing the Garbogen, Hughs 4 ft pma and the 14-11 when I get it done.

Heres a blury picture of the Garbogen PMA and the laithe.

Here a picture of the Fluke measuring no load voltage.

These 2 machines should be close in preformace scince there both 1 hp?

                   JK TAS Jerry

[valterra]

Had to work this morning.... lathe tests will be tomorrow at the earliest

[valterra]

Real numbers this time, Gentlemen:

3 Full-wave bridge rectifiers, FYI, Hooked up Low Volt Jerry Rig

Open Circuit Test:

 153 RPM - 10.1 Volts

 303 RPM - 20.7 Volts

 403 RPM - 27.8 Volts

 652 RPM - 45.4 Volts

They're a few rpm off a round number because this was the ACTUAL RPM.  For example, we set it to 150 RPM, and then the ACTUAL spun-up speed would be 151-154 average, etc.  

Current Test:

RPM       "Resting" Voltage     Amperage     Charging Battery Voltage

 203         11.98                 0.54          12.05

 353         11.00                 5.48          12.05

 602         11.05                14.11          12.41

 702         11.06                17.12          12.40

The little leads on my HF  "10A" Multimeter (The $3 one) got a little warm.  Seriously, just a little warm, after the 17.12 test, which we did twice for several seconds (just to be sure).

First 2 Current tests (203 and 353 RPM) had a 55W incandescent bulb on the inverter.

Second 2 (602, 702) has a 120W incandescent bulb on the inverter.

[valterra]

"These 2 machines should be close in preformace scince there both 1 hp?"

So far, that seems to be correct, Jerry.

[valterra]

Only 9k, so I don't wanna hear about it, Woof!    :-)   lol.

[valterra]

203 RPM is putting 500mA into the battery.  Doing the math on Rpms per Volt on the OC test, I get about 190-200 RPM for 13 Volts.

So I should figure approx 200 RPM would be a good cut-in speed?

Are these correct, then?

A 7 foot, TSR 6 rotor should reach cutin between 5 and 10 MPH and would be trying to put out over 200 Watts in a 30 MPH wind.

An 8 foot, TSR 6 rotor would cut in just under 10 MPH and would be trying to put out over 200 Watts in a 30-35 MPH wind

Seems like in the calculator program I am using, as the rotor gets larger, the Cut-in gets higher (windspeed) and the RPM / MPH gets lower.  

So there must be a "sweet spot" (Flux, you called it "compromise") between the lower speed, more powerful large rotors, and the higher speed, less powerful small rotors.

Sorry if all of this is coming out of my backside.  Don't crucify me.  lol.  I appreciate hand-holding as much as the next guy.  But you guys should know me well enough to know I'll try to do MY due diligence in researching (and guessing) the answers.

[Flux]

Too near bedtime for serious thought but I think you have an ideal alternator for a 6ft fairly slow prop in a high wind area or a 7ft prop if you want a bit more out in a lower wind area.

The cut in speed will still work for an 8ft prop but you seriously have to ask yourself if you can furl it in a low enough wind speed to live with the noise in  higher winds. You will not have enough alternator loading to keep the speed reasonable.

Will have a better look tomorrow.

Flux

[valterra]

Thanks, Flux.  I will look for your response tomorrow.  

6 foot is obviously much more manageable than 8 foot.  That goes for everything from mounting to furling.

[Flux]

I stick with what I said last night.

The cut in is a bit low for 6ft but the power level suits well. For a motor conversion you will need a lowish tsr and you will need to follow the calculator well towards the centre for a fair bit of chord and twist to get good starting.

Tsr 6 will probably be ok. ( could try 5.5)

It will take 7ft and again tsr 6 but you may not need to go so severe with the dimensions near the root as you have a bit more starting capability.

I wouldn't attempt 8ft unless in a very low wind area and it would be better at tsr7 but it will be noisy when the speed gets up to 600rpm and more and you will have a real challenge furling it. The very low wind part would be good if you could control it but I think I would stay safe with 6 or 7ft.

Maybe 7ft as a good all round compromise unless a very windy area.

Flux

[valterra]

Thanks again, Flux!

If I find that I still cannot find access to a band saw, I am thinking of getting a set of blades from The Dans, especially since they've started producing a 7 foot machine for sale.

But I don't know what TSR their blades are.

[SparWeb]

Hi just wanted to chip in a congrats for the project so far.

Thanks for posting the data, too.  I love numbers.

[Jerry]

I'll try to do some RPM, amps, volts watt tests today and report back some #s tonight?

We'll see just depends on how the day goes?

                              JK TAS Jerry

[Jerry]

Well I did a bunch of testing today.

The Garbogen is running at much higher RPM for the same output.

I tested it from .5 amp to 10 amps. Here are the #s.

  .5 amp, 347 rpm cutin

   1 amp, 371 rpm

   2 amp, 410 rpm

   3 amp, 433 rpm

   4 amp, 464 rpm

   5 amp, 485 rpm

   6 amp, 508 rpm

   7 amp, 533 rpm

   8 amp, 555 rpm

   9 amp, 582 rpm

  10 amp, 621 rpm

My 4 ft blades run prety fast with an estamated TSR of 6.5.

Looking at your RPM #s I would go with the high TSR 7ft as Flux has sugjested.

Your making more power at lower RPM then I. So this will requier a more powerfull and larger blade then my 4 ft.

I'll post the story more indepth about todays testing next.

                  JK TAS Jerry

[SparWeb]

Hi Valterra,

Do you have any plans to try 24V?  Try a Hi-voltage Jerry-connection or Parallel-Star and bring another battery along.

[valterra]

Well, Steven, I have.  But  only because of the idea that I might squeeze an extra amp or two out of it.

Back on earth, I have to remind myself that 24v is completely worthless to me.

Don't get me wrong.  If I bought or built a system and X voltage was the most appropriate (24, 48, 72, whatever) I wouldn't fight it.

But with the wide multitude of 12v stuff available off the shelf, I don't see myself using anything but 12 except for a large system-wide configuration.