ECM motor testing and trouble

[wingman1776]

For my first windmill I got a ¾ hp ecm motor.  When I first started to test it I left it alone I took the 3 wires from the motor ran them to a huge full bridge rectifier to a partly discharged lawn mower battey I have I spun it with a ½ inch right angle milwaukee  it spins at 400 rpm. I got 6.2 amps at 13.8 volts into my battery. I read every thing I could find on the board about the ecm motor and from what I read the best way for 12 volts was to separate the star point and use continuity tester find the ones that make a circuit run those 2 wires to a bridge and do that with all six ends. So I did that when I hooked  it back up to my battery and spun it with the same drill I only got 3.2 amps at 13.7 volts. This did and does not seem right to me so I went out to the truck got a hole hog out it has 2 speeds 350 rpm and 900 rpm at 350 rpm I got 2.97 amps at 13.7 at 900 I got 6.2 amps at 13.8. I do not understand why the amps are so low now. I used a 6 line water proof trailer plug I found to rewire the motor and have 2 of them so I rewired the star point back together and used the big full wave bridge at 350 rpm I got 3.2 amp at 13.7 at 900 I got 4.1 amps at 13.8. What have I done wrong? Why did the amps on the motor go from 6 amps factory at 400 rpm to 3.2 amps at 400 after the rewire? I also do not understand why it did not return after I hookup the start point back up?  Are the numbers good for ¾ ecm I ready though I would get more watts out of the motor then this. Have camera will post any pics needed for someone to help me if you need them. I had hoped to get maybe 300 watts out of this motor at 900 rpm not 85. not a clue what is wrong advise needed plz.

[Rover]

Actually, I find the later readings more in line with what to expect from the ECM, even those I find a little high at 400 rpm. 6.2 Amps/400 rpm, wow.. thats good, considering that very close to the usual cut-in speed. I would tend to think the other readings were fine and the first was off. I have no idea how it can be off yet higher though.

Is the usual GE ECM, withg 18 coils?

[wingman1776]

yes it is a standard ecm motor made by emerson came off reem furnace

[Rover]

Although i was talking about a treadmill motor. look at the graph in my post http://www.fieldlines.com/story/2009/12/16/153710/66 which also shows my 1/2 hp ECM.

I think your goal of 300W is a bit high at the 900 rpm mark , that puts you in the 23 amp range. (assuming 13v battery).

[Rover]

Also note, that your later readings are very close to my graph and the output of the ECM

[hiker]

http://www.fieldlines.com/story/2008/10/5/234933/273

or google search the board---ecm motor  jerry --

where is jerry  havent seen him around for some time............

[ghurd]

The numbers look about right to me.

"Best" depends on the objective.

Do you want a low cut in RPM, or a higher output at a high RPM?

Do you want simple and lower output, or complicated and higher output?

It is robbing Peter to pay Paul.  You can make it do anything, but not everything at the same time.

Changing one thing changes everything else.

If you want to put it back to factory Star, the exact same 3 wires need connected together.

Sounds like one is connected backwards.

G-

[Jerry]

Hi Wingman.

The Emerson is considerably diferant then the GE ECM. As a mater of fact Emersom calls there motor EPM.

If you disasemble both motors and compair the stator you will see that the EPM stator resembles a convetional  6 pole ac motor.

The GE ECM stator has 18 easly seeable and countable  individual pole pices/coils.

I fly both the Emerson EPM and the GE ECM. I've found for best blade match and requiered rpm. The Emerson works best with star seperated and 6 wires down, Jerry rigged with 3 bridges.

The GE ECM works best with 3 coils perelelled with 3 coils per phase per phase.

Then Jerry rigg as above. These machines work well with a 4 ft diameter blade at a TSR 6.5.

You may see 300 watts from a GE ECM at 30 plus mph. Not sure about the Emerson?

                 Jerry

[Bub73]

"The GE ECM works best with 3 coils perelelled with 3 coils per phase per phase."

Is this true for all GE ECM's ?

 I have one each 1/3hp 1/2hp. and a 3/4 and live in a mostly low wind area. would the paralleled coils make cut in to high for my low wind area 5 to 50 mph but mostly in the 5 to 15 range.

 Thanks and a great forum

   Bob  

[Rover]

I believe what Jerry was alluding to was for 12v battery charging... (not 24v etc), and I can agree , (at least with the 3 GE ECM's I have done, it does bear out

[Bub73]

Ok, thanks for the quick reply.

 I have a 12 volt system at the present so I'll give it a try with one of them.

 Bob

[wingman1776]

I want to thank everyone who answered I think I have a handle on what I need to do now.  This is the way I am wired right now with the star point separated I right now have a 3 phase generator with 6 coils in series the 3 phases are marked with red blue and black

Wired like this I got the readings I posted earlier what I need to do I wire my generator as 6 phases with 3 coils pr phase coils wired in parallel I posted a pic of how I think it should be wired I have the 6 phases marked as red orange green yellow blue black with the coils wired in parallel.

I hope like this to see close to 12 amps at 900 rpm wire this way I was looking to the 300 watts at around 30 mph or 1250 rpm.  If how I am planning on doing this is wrong please let me know I hope the pics help anyone else who is going to do one of these motors I was wrong earlier when I said the motor was an Emerson it is a GE and to jerry rig it I will need 6 full wave bridge rectifier I will post what I get after the rewire and I hunt up one more rectifier

[wingman1776]

yes this is for 12 volts

[ghurd]

There is no need to break it apart as far as you are planning.

The first 3 coils in a phase can be wired in parallel with the last 3. If you break it down too far, it'll be a bugger getting the wires solid and contained.

No need for 6 bridges, because sets are electrically parallel.  Only need 3 bridges unless you are going to try some more unusual scheme.

This one was rewired electrically the same as I think you are contemplating,

http://s701.photobucket.com/albums/ww20/ghurd1/ECM%20Conversion/

Make sure nothing is able wiggle inside.

G-

[Bub73]

 ghurd;

What is the cut in rpm for 12 volts wired this way?

 Thanks for the photos, this looks to be the same as the 1/3hp I have.

Bob

[ghurd]

I am Not a big believer that all of them of the same HP are actually the same.

After rewiring, the 12V one in the photos cut in at about 280RPM, IIRC.

Best to test a single phase, then do the math for predictions concerning rewiring.

G-

[Bub73]

Thanks;

 I'll post back my findings; maybe a few days kinda busy here with the better weather.

Bob

[taylorp035]

If you could get a 200-300 rpm cut in, that would be awesome.  I nice 6 ft diameter would have an awesome low speed performance.

[ghurd]

Be careful what you wish for!

Not a problem to get 150RPM, or maybe 80RPM cut in.

(did you see the video in the link I posted?)

http://s701.photobucket.com/albums/ww20/ghurd1/ECM%20Conversion/?action=view&current=PICT0819.fl
v

But it brings up issues with stall, low efficiency, and inductance limited output.

If the output is limited to 60W 4A max at 12V in a hurricane, no reason to have a 6' blade, and plenty of reasons to have a much smaller blade.

G-

[wingman1776]

Ok I have separated all the coils on my motor and wired them with 6 different color wires red and red with black stripe orange green yellow white and blue. All starts solid color all end have black stripe. I did the red orange with one of the factory phases green yellow and blue white with the other 2. I ended with a bird nest that looks like this.

This was a bit of a pain and like gurd said will be a bugger to get landed there are plenty of place to tie wrap it. I will shorten and land the wires after I am done testing.  I did not see gurds post about the coils before I broke them all apart. I would have tried that first what I did took a bit of time. I may test it that way I am not sure yet first test with the motor will be like in the pics all starts paralleled and all ends paralleled into 3 bridges  

[ghurd]

Wow!  

(it sucks to be you about now... LOL)

You can try every possible combination like that.

I often wondered about trying one in Star, with only 'one series coil' per phase (meaning each phase wired with all 6 coils in parallel).

The 'overlapping coils' (not the correct term) should give more voltage that it first appears.  I think.  

It would probably stall badly a little past cut in.  I think.

I never had the guts to break one down that far.

Be Very careful not to wiggle them too much.  They only wiggle so many times before they snap off.

And they snap off where it is hard to get at them, especially in that style can.

Just for giggles, connect all those wires together, and see how fast you can turn it by hand.

Now sure why, but it always makes me giggle.

G-

[wingman1776]

OK first round of tests with the motor all paralleled I got nothing at 350 rpm but at 900 I got about 6.52 amps into a 13.7 battery. So then I star wired all the end coils and again at 350 I got nothing but at 900 I got 9.45 amps into a 13.8 battery  130.4 watts not to bad so I got out my right angle at 400 I am right on the edge on cut in  I think. I seen it blink .04 amps couple times when the battery was under a 15 amp draw  at 11.54 volts I did the star test with the 15 amp load too and got 10.54 amps with 12.5 on battery.  I would like to bring the low end up a bit if I can any suggestions for my next test? I am planning a 4 foot dia blade set.

[ghurd]

I would suggest trying each phase individually rectified (IRP, formerly 'jerry rigged').

Each phase as 2 series coils, 3 pair in parallel.

With a 3/4HP that May put the cut in at around 250RPM.

I suggest testing the open voltage at a known RPM.  It will help people make better guesses.

Like I said, I am not a big believer they all act the same.

And that style can is a bit more unusual than the other styles.

G-

[wingman1776]

When I did open voltage with all the coils parallel at 350 RPM I got 4 open volts dc at 900 RPM I got 16.2 and in star at 350 RPM 7.5 at 900 RPM 29.4. I want to make sure I do the rewire right I have attached a pic of what I think you mean the blue and white on the coils are one factory phase the starts are the red lines the black are the ends  I think the second pic is the right was but does it really make a difference?

[ghurd]

Kind of hard to follow, but it looks right and both look the same.

All 6 coils are in phase, so they all do the same thing at the same time.

G-

[wingman1776]

Thanks gurd for the rewire suggestion I rewired the motor as pr suggestion check open voltage at 350 RPM 8.5 volts DC at 400 RPM 11.5 volts much closer. So I added in the battery and tested with it at 350 RPM 0 amps at 400 RPM 0 amps at 900 RPM 10.54 amps. It is very close wired like this. I decided to star it up the first test was jerry ridged at 350 RPM I had 15.5 volts dc open that is just about right I think. So I hook up the battery at 350 RPM .59 amps 13.1 volts at 900 RPM 9.6 amps 13.5 volts.

I think for my motor this is the way to wire it. At 350 RPM is just about 8 MPH with a 4 foot 6.5 TSR blade set. Max watts available at that wind speed is 32.67 WATTS. I get 7.7 WATTS that is about 29 % eff from what I have read most windmills are 30 % eff at the most. At 900 RPM is about 19 MPH with the same blade set max WATTS available 437 I get 129.6 WATTS again about 29 % eff . I have improved the output at 900 RPM 65.4 % with the rewire and not killed the low wind. I think if I tried to fly it the way it was it would have stalled in low winds and I would have not gotten much in high winds. I think now I will get the 300 WATTS in 30 MPH+ winds. I got all the wind speed RPM and WATTS from copy of wind power excell spread sheet I am not sure of the author.

Now I wonder how much it will take before it burns up. I have not read about anyone who tries to make one of these small machines furl.  Does a small mill like this need to? Anyone had one burn up? I have not gotten to that part of my build but I hope to soon. I will land all my wires post a pic of motor when done. Thanks everyone for you help.  My next project is blade building. I have a plan for that will post about it in another thread with pics.

[ghurd]

Ain't this fun?

I am not sure if one can be burned up with direct drive wind.  I never heard of it.

If a wire starts to crack (half snapped) then yes it could happen, especially with a controller using a braking scheme.

I bought more than my share of used ebay ECMs with wires burned-off and half burned-off from 120/240V grid power.

I doubt wind will burn it up if it starts in good condition and there are no electrically weak points because of the inductive reactance.

They hit a current plateau relatively early.

Because of the current plateau, and it is NOT linear, it would be great if you could test the actual output at more RPM points.  Yea, I have a problem there too.

"I decided to star it up the first test was jerry ridged at 350 RPM I had 15.5 volts dc open that is just about right I think."

Uh... What?

If that single coil Star thing did not work out, I would Really Strongly like to recommend Only Individually Rectified Phases (jerry rigged).

If 2 coils in series and IRP doesn't quite do it, try 3.

I hear people say the 1/3HP is the same as the 1/2HP, and the 3/4HP is the same as the 1HP.  It doesn't work that way for me.

The last 1/2HP I did cut in at 200RPM (3 series coils paralleled with the other 3 in the same phase, then IRP).

There are some very strange inductive reactance things happening in these motors that are hard to explain or understand.

Matters get more exponentially more confusing if the testing only includes 1 phase, so test with all 3 phases connected.

"ECMs are like a box of chocolates... you never know what you're gonna get",

unless you want a caramel and pick the square one,

because then you certain to get one of those sickening sweet pink creme things.

G-

[wingman1776]

I decided to star it up the first test was jerry ridged at 350 RPM I had 15.5 volts dc open that is just about right I think."

Uh... What?

  I was testing all 3 phases when I was testing and I wired all three of the ends together when I wired in star.The open voltage I reported was with all 3 phases. I do think that your orginal sugestion of 3 series coils then paralled is the way to do one to cut down on the work. the rewire I have done is not easy by any means but can be done you just have to go slow mark you wires well spend lot of time. lol

[Bub73]

My 1/3hp is coming along nicely also, thanks to ghurd and everyone else here.

 I worked one phase at a time and settled on 2 sets of 3 coils paralleled per phase for 2 ohm total per phase then jerry rigged. Cut in on the bench with a cordless drill is about 250 rpm, @ 300 rpm 17.63 volts at about one amp, into a small 12 volt battery briefly at 550 rpm 9.2 amps.

 I'll try it on our test stand next week hopefully and see what it does in our low wind.

 Thanks to everyone

 Bob

[wingman1776]

Well I got it all landed I am glad I did not make any more series coils then I did the hooking them back up and landing them was a pain. I do have one suggestion for anyone doing this when you go to land your wires put the zip ties in first then hook them up and route them around pic of the series coils landed

Then all I had to do was the star and the 3 phases

I am going to bring 3 wires down the tower and rectify at the batteries.

[ghurd]

Looks good.

I suggest replacing the zip ties with some better quality.

The colored ones tend to fail in a fairly short time.

I use the hard to find expensive UV resistant black ones.

G-

[Rover]

I went back through my earlier posts... here is one showing different wiring schemes and what I got at each (graphed) for the 1/2 HP ge ECM

http://www.fieldlines.com/story/2009/10/24/10402/805

[wingman1776]

Well I finished up my wiring and ran out 3 14 gage wires and closed the can. I hook the motor back up to test rectifiers to the battery I put a 15 amp load on my battery it was at full charge. I spun the motor at 350 RPM and got a solid 1.5 amps into a 13.1 volt battery at 900 RPM it went off the scale on my cheap vom it is only fuse for 10 amps so I stopped right away lucky I did not blow the fuse. I got out a 12 volt car amp gage and wired it in let the dump run while I was doing this. I spun it back up to 900 RPM I was getting 15 amps at 12.54 into the battery and it held it there for 5 min. Wow what an improvement. I went from 129 WATTS when testing to 188 WATTS at 900 RPM when landed and at 350 RPM 7.7 WATTS testing to 19.6 landed. Not sure what was not the same but I am very happy with the rewire now to just get it flying