Feigo Coils all the same?????

[Dick Crowe]

Hey Don,
You had mentioned to me and a few others at nats that all Feigo motors used the same coils and that they just changed the magnet strength to achieve the different KV's throughout the line. I mentioned this to Joerg and we decided to put it to the test as we needed something to do in my Garage Sunday night while digesting the Lasagna!!!

Anyway, Joerg, Arne, Gunnar, Matthias and myself did the test.
The motors we tested are below. We used a 13.5 amp power supply and a 9.2 amp load. The impedance numbers for each set of windings are below. It sure seems like the feigo has different winds when comparing the 8XL's to the 10XL.

Feigo 8XL red/yellow - 72.1, red/blue 72.1, yellow/blue 73.8
Hacker B50 8XL red/yellow - 72.6, red/blue 73.0, yellow/blue 72.8
Hacker C50 8XL red/yellow - 71.4, red/blue 71.1, yellow/blue 71.0
Feigo 10XL red/yellow - 112.9, red/blue 113.6, yellow/blue 114.6

The numbers may vary a few points between all three phases of the wires due to all of the hands involved holding the motor, load wires, test leads, it was like a game of twister (actually, my job was writing down the results, they wouldn't let me play with any of the wires!). Bottom line, we weren't striving for perfect accuracy, we just wanted to know if the 10xl and 8xl had the same coil. It doesn't look like it.

Could they have changed the manufacturing procedure since your involvement with these a couple years ago? I've spoke to a few others who think that it is possible to get maybe 1 wind difference with magnet strength but to be honest I don't know which was why out little test was kind of fun! I'm all excited now to check my other motors to see how close the winds are from phase to phase, mostly because now I know how to do it! Seems like the more I know the more I don't know! What's new right?

Dick

[Andrewg]

Dick

Neu tested the B50-9XL Feigao - his results are right in line with thoe of yourself and those other fast guys standing still.

(Hey thanks for the LSH record with the Cabover 24 at saws)

[Don Wollard]

Dick -

The motors I had from Feigao where early motors indeed. I haven't a clue on some of the later motors. The early motors had coils from Tiawan, not China. What we did was cut the motors in half with a ban saw and count the wires.

There are some adjustment on those motors you will need to account for if you are testing your way. First - they use a low grade industrial bearing so you could likely discover a difference in the performance of identical motors. We found a difference as high as 20% in motors which were suppose to be identical winds.

My engineers noticed a similar difference in the motors as you did but a slight change in the magnetic curcuit could easily account 10-15% variation. We actually have duplicated this with some of our testing in Florida. I can take two motors with identical coils and change the idle amp draw by as much as 100% with a minor change to the rotor strength. Then .... if I do a test similar to what you did I too would get different numbers. We used such testing (slight changes in the rotor strength) on the Chili CP20's to determine the best most effective Kv's for a particular motor size for RC applications.

Have fun. Cut a couple motors open and count the wires.

[Dick Crowe]

Hi Don, Actually, we didn't run the motor, we tested the impedance on the coils. You know, longer wire, more resistance. The 10XL was way higher then the other 8XL's. All of the Hacker and Feigo 8XL's tested around 71 where the 10XL Feigo tested at around 114. Not even close.

I realize you found as much as 20% differences. But in our test we show a 40% difference between the 8XL's and 10XL. I was actually surprised that all of the 8XL's were so close to each other. The feigo was within 1 to 2% of the B50 Hacker and C50 Hacker right in the middle.

I suppose in the end cutting open a few would answer the question as well, but I'd be willing to wager they have different coils these days.

What is also interesting are the dyno results between the Feigo and the Hacker. I would have expected them to be closer to each other then they were based on the impedance test. I'm glad I run Hackers!

Happy Thanksgiving!
Dick

[pin]

Originally posted by Don Wollard
Dick -

The early motors had coils from Tiawan, not China.


Hi Don

You say the Feigao early motors had coils from Tiawan.
WOW...
It's made me amazed!!

I had bought several Feigao XL motor few days ago but personally send for by a phone call from Taiwan to China.
I know the Feigao dealership in Taiwan...
(they only bring in the 400~480 size BL motor for electric airplane)
but i really don't know the Feigao motors had coils from Tiawan!

Don...
Do you know the factory place of Taiwan?

Thank you very much.

Pin

[Andrewg]

Don

Sawing a motor in half and counting the wires????????

Is this a technique you use often?

[Don Wollard]

Originally posted by pin
You say the Feigao early motors had coils from Tiawan.
WOW...It's made me amazed!!

Couple years ago, BMI joined with another US Company and sent a Trade Rep and an EE to China to look around. These guys spend a day at the Feigao factory. At that time – Feigao didn’t own a coil winder. So you know, this was a first hand observation. Both of the fella’s who visited the factory are of Chinese decent and had nothing to gain except for the fee they charged for an extensive report. A company in Tiawan made the coils for Feigao at that time. In fact, there are several houses on Tiawan who make excellent coils for BL motors.

Originally posted by Dick Crowe
Hey Don,
You had mentioned to me and a few others at nats that all Feigo motors used the same coils and that they just changed the magnet strength to achieve the different KV's throughout the line. Dick

Indeed – we had a conversation. You and I only spoke about L and XL size motors. Nothing more. I specifically referred to Kv’s suitable for model boaters. That is what we tested.

Originally posted by Dick Crowe
The impedance numbers.....

Appologies. I was busy with Holiday festivities and only scanned your post. I phoned the EE who did the initial test for us. He is up north for the holiday. He will send me a copy of his report when he returns.

Originally posted by Dick Crowe
Bottom line, we weren't striving for perfect accuracy, we just wanted to know if the 10xl and 8xl had the same coil. It doesn't look like it.

The only way to know for sure would be to locate one or more of the early motors and do a little comparison. I gave mine away after we were done testing. I emailed a guy to see if he still had the 8XL. I still have the 8XL Hacker that you used for the very first 89MPH run in LA. Remember that motor??? After the holiday, I will check the numbers on that motor and see how close it comes to the Hacker you tested. That could make a nice bench mark to see the accuracy of such a comparison.

I’m outta here. This is the Turkey Hot Rod Run @ Daytona and I off to see some krome.

[Dick Crowe]

Originally posted by Don Wollard Indeed – we had a conversation. You and I only spoke about L and XL size motors. Nothing more. I specifically referred to Kv’s suitable for model boaters. That is what we tested.

Sorry if I had implied anything different. Our intention (out of curiosity sake) was to do a test to see if a 8XL and 10XL had the same coil. I can't speak of any of the other sizes, we only had the 8XL and 10XL for comparison. We did try to rule out as much error as possible which is why we tested 3 different 8XL's (the Feigo, C 50 Hacker and B50 Hacker). As I mentioned earlier I was really surprised all 3 8XL's were so close to each other, at the least it helped legitimize the claim that the 10XL indeed has a different coil. I'm sure some kind of argument can be made that manufacturing differences could account for the differences between the 8XL and 10XL but it would take a more active imagination then my 5 year old daughter, Princess Abbey to come up with that.

Bottom line, coils of the three 8XL's we tested were less then 2 percent from each other top to bottom. The 10 XL was over 40 percent different from the 8XL's.

I could have never done these tests without my 4 EE's. Joerg, Matthias, Arne and Gunnar. There conclusion......Different coils between the 8XL and 10XL.

I'm sure I can get my hands on a few more motors and see what they come up with now that I know how to run the test.

I realize the early models that you cut open with coils from Taiwan were then same, but it appears things have changed, at least with the XL's.

A better (running) evaluation of the motors would have been nice, but no dyno in my shop. We just wanted to know if the coils were different. The closest empirical comparisons I've done are with my Emaxx and GPS. Motors were an 8L Feigo and 8L Hacker. In this case the Hacker came out on top by an average of 4 to 6 percent. There certainly could have been some "driver" error, but no matter what I did or how I drove I couldn't get as much speed out of the Feigo.

Hope you had a good cruise!

Dick

[Andrewg]

Don

The Feigao bearings are rattly which reminds me I have to replace Hackers' this weekend.

Dick

Your results are consistent with published figures for Feigao/Nemisis

I had a Chinese friend in Ghanzou get some of the earliest data on the Feigaos. The specs then are the same as the ones on the feigao site now. (BTW if anyone knows how Chinese student who is completing his doctorate - thats at least 7 years of college can afford hackers and schulze for his race boats I want to know!)

Published tests of different diameter and length and wind Feigaos show they use windings of different electrical characteristics. Quiet Flyer now publishes the Ir and Io of each motor dyno tested. This should avoid the use of incorrect (manufacturer) information.

So far the results show the resistance figures for the Feigaos are:
* the same as Hackers of the same size and wind
* Feigao resistance is 24% higher than stated in the Feigao stats
* Feigao Io figure for a wind is about half the actual - but is a tad optimisitc for the Hacker B series.

Your road dyno (E-Maxx) is a very useful comparo for 2 motors. Am I right in assuming you used the same controller and cells?).

Having looked at what you get out of motors across a range of setups, I know if anyone can squeeze the mph out of a setup you will!

(BTW I had a look at some of your recent work - thanks its sweet!)

[xzd]

Hi All,
Your discussion about Feigao motor is very interesting. I only have 380 size motors and I tested a 9L recently.

I use 1A test current. The resistances between each two of the three wires are all about 14mOhms. That's very close to Feigao's data sheet and Hacker B40-9L.

No load current is higher than Hackers. My 380-9L is 2.3A at 8V on SCHULZE while Hacker B40-9L is 1.6. But I don't think this will decrease the efficiency by more than 3%. When run the motors with 7cells at 30A, the input power is around 230W, but iron loss difference is only (2.3-1.7)*7.7=4.62W. That is only 2%. What's the problem? Is there any mistake in my calculation? Or the Feigao's big motor has poorer quality?

Xie

[Andrewg]

Xie
I will send you some dyno tests they make for interesting reading

[GunnarH]

Originally posted by Dick Crowe

... they wouldn't let me play with any of the wires!...
Dick
Oh no, we would have, but your bench is too small ;)
And actually writing down the results is as important as the measurement itself.

Gunnar

[xzd]

Thanks Andrew!

[JfromJAGs]

Concerning counting wires in a cut motor: these motors are no single winds, they use many wires in parallel.

Now, a 8 wind with 5 wires in parallel (8x5) will give you the same 40 wires when cut appart as a 10 wind with 4 wires in parallel (10x4). You would even end up with the same filling factor.

This is usually done by the manufacturers to reduce the number of different wire thicknesses they need to have in stock to do different motor winds. So for most motors the same wire is used, it's just a matter of how many winds and how many in parallel.

Could this solve the miracle?


BTW, the numbers presented by Dick are mV measured over the internal resistance at aprox. 9.2A current. So to get mOhm values these numbers need to be devided by 9.2, which will derive number very close to what Hacker gives as mOhm numbers on his web page.

Joerg

[Don Wollard]

Originally posted by JfromJAGs
[B]Now, a 8 wind with 5 wires in parallel (8x5) will give you the same 40 wires when cut appart as a 10 wind with 4 wires in parallel (10x4). You would even end up with the same filling factor.

Pretty much right on the button, Joerg. There are several other issues we noticed. In some of the L and XL size motors, they used pretty much the same coil but wound in wye. Others where wound in delta - same wire and pairs. The interesting difference we noticed is how the chinese coil manages the end turns.

This is usually done by the manufacturers to reduce the number of different wire thicknesses they need to have in stock to do different motor winds. So for most motors the same wire is used, it's just a matter of how many winds and how many in parallel.

Sometimes. Mostly I think 'Low Bid' is actually what determines a lot of wire size and quality some of these guys use. Lets face it - it not very hard to reconfigure a coil in the event a super deal was had on the cooper. I actually have some evidence of this. During testing in a motor lab last year - we also paid to have several 8XL hackers cut apart. one of the motors was an older motor and saw action at the 2001 SAW's. Another was a recently purchased motor - with an identical label. Guess what .... they both put out the same Kv's but displayed a different resistence. The new motor didn't have 8 turns. Pretty funny, huh!

Hey Joerg. I have a question or two. Dick's post was confusing to me. If I may;
1. What wind config was the Feigoa motor you test. Could you tell?
2. Did you guys spin the shaft or hold it & motor stationary?

[AndyKunz]

2. Did you guys spin the shaft or hold it & motor stationary?

The shaft wouldn't have rotated more than a few degrees and established equilibrium - the same resistance would have been measured had the arm been locked or allowed to center itself in the field. Remember, they are only energizing one field at a time.

Andy

[Don Wollard]

Originally posted by AndyKunz
The shaft wouldn't have rotated more than a few degrees and established equilibrium - the same resistance would have been measured had the arm been locked or allowed to center itself in the field. Remember, they are only energizing one field at a time.

Andy

That wasn't clear from Dick's post. So I asked.

It would have made a difference in the event the resistence across the coil was the attempted goal. That is what I understood they measured.

In the event the shaft is not locked in one way or another you will likely get a difference result - motor to motor. We discovered this a while back fooling around with a Magtrol dyno. I have some dyno time coming up later in the month and I will try to duplicate the outcome the fella's got. I have arranged one of the world's top motor engineer's for coaching.

[Dick Crowe]

Andy is correct Don.

In any event, you still have 3 8XL's of different manufacture (B50, C50 and Feigo) All 3 phases tested and the MOST deviation between the motors was 2 percent. Seems fairly respectable since they were not identical motors. The C50 8XL and B50 8XL were the farthest apart with the Feigo 8XL in the middle. The 10XL feigo was 40 percent different from all of the 8XL's. WOnder how different the results would have been had we of locked the shaft? I doubt the 8XL's would have been so close.

I'm not trying to make any case for the Feigo's, You know me, I'm a Hacker guy, and after the SAW's more now then ever. For the most part I understand how a brushless motor works or thought that I did but was having a hard time swallowing the same coil different magnet theory in the Feigos you had mentioned to us at the NATS. It would have meant I know even less about this stuff then I thought I did. PLEASE don't think I was trying to prove you wrong. You just gave us the opportunity to have a little fun out in my shop after dinner.

I'm glad that Joerg mentioned the different grouping of strands in the same can. It explains why you had thought they were all the same when you cut some cans apart.

What is interesting is how close all 3 8XL's were. If the Feigo's do compromise their winds it seems they got the 8XL very close. I wonder what a Magtrol would show? All three also have different magnets. What was really interesting to me was the differences between the B50 8XL and C50 8XL at the SAW's. Performance was nearly the same with the edge going to the C50 but the Batteries AND Motor were nearly 35 - 40% cooler with the C50 under the same conditions.

Dick

[Don Wollard]

Originally posted by Dick Crowe
[B]Andy is correct Don.

Really! I am not sure. Default this chat to the motor industries own engineering guidelines for such test. On Friday I received about 40 pages in the Fax from a Pal who is a respected motor engineer. Seems - from what I read in this techno-stuff a few degress variation/movement could be significant in such a test. Movement of any nature distorts the test. Whether the rotor is centered or not- it has to be locked for the test to be accurate.

When I get on the dyno, Dick - for kicks it would be cool to see what variation shows up between using fingers to hold motors wires to a power source vs direct solder contact. I am curious. I would bet the difference is noticable on the same motor

The 10XL feigo was 40 percent different from all of the 8XL's.....For the most part I understand how a brushless motor works

Indeed - you are one sharp dude, Dick. I am a little slow - so I have to get a pro to explain me the simpliest things. Its just an over 50 thing, right.
So ... I have to ask, doesn't this seems strang to you that 2 add'l turns on a Brushless Motor coil would yeild a 40% difference? Does to me, but I am not the expert. Either there was an error with your testing method -or- use guys where not comparing apples to oranges. Could you have tested the same identical coil - one motor wound delta and the other wound wye?

PLEASE don't think I was trying to prove you wrong. You just gave us the opportunity to have a little fun out in my shop after dinner.

:) Funny guy! No problem either way - makes great chat and a learning experiance for all.

I passed this thread by my Pal who is the motor engineer that supplied me with the original test and data on the feigao's. He chuckled. But - stands 100% by the initial test. I am with him.
BTW - he is not a hobbyist. He is a EE/PE and a senior member if the IEEE. He over see's the production of over 10,000 BL motors a months and just finished engineering the latest motor technology for inline heart(human) pumps. The world will get to see his work next spring when NASA's latest solar powered aircraft attempts an around the world unmanned flight. Donnie and I have one of these motors - its very impressive.

I'm glad that Joerg mentioned the different grouping of strands in the same can. It explains why you had thought they were all the same when you cut some cans apart.

Good explanation - but wasn't the case of the motors we tested. A good engineer can tell how a coils is configured. All looks the same to me.

I mentioned above - we have done extensive testing using identical coils, just configured differently. One wound in wye and the other delta. Dick - identical coils. The magnetic circuits where altered so the motors produced almost identical Kv's. Typically - and depending on the size motor, the differences measured ranged in the 30 - 40%. Ring a bell? Why? In some cases - the efficency factors where even more significant. Again, same coil.

For example - the C50 motor in 8XL size incorporates the same coil with a different rotor, as you noted. The performance was significantly different is you compare heat variant. Are the Kv's similar - what % different? The C series motors was intended to operate differently that is why you see the same coil with a totally different designed magnet. ;) ;)

[Dick Crowe]

Thanks Don,

You made my morning when you started off calling me "one sharp dude". If nothing else I got that out of this thread!

Also, I did the math and came up with a 36% difference between the 10XL and the 8XL's (my 40% quote was an estimate for basic evaluation, this time I did the actual math. Sorry for any confusion this may have caused). Perhaps this is too high?

Testing 4 motors by no strech gives me any kind of expertise on these matters. Lets just say we did botch the test up according to your engineers. A few things still stand out in my mind.

1. locking down or not, the 3 phases of all motors showed less then 1% difference. There was a 1-2% difference between all 8XL's and a 36% difference between the 10XL and the 8XL's

2. Perhaps a few degrees rotation that you EE's mention account for the very small differences between the 8XL's but I can't see how it would explain the 36% difference between the 8XL's and 10XL?

3. If your enginers statements DID account for the differences between the 8XL's and 10XL I would have expected the 8XL's data to be all over the map instead of within 2 percent of each other and they weren't.

4. Perhaps the Feigo did use the same coil in the 8XL and 10XL in a different wind configuration, It still tells me it's not the exact same coil with a different magnet, doesn't it? I'm running my Lehner 1930/6 in Asterisk mode in my sons e-max and it's incredible, I've got to thank Donnie for that one. He was the one who suggested it to me. I couldn't even run it in that application until I changed it. A cool trick!

So, would can motor manufactures think a 13x7 arm and 7x13 arm are the same? They would have the same wire count if you cut them in half but be totally different motors. The torque would really be bad on the second motor as well! Perhaps this would be the flaw in the Feigo wind system? Torque for RPM/V by different wind methods? Although, that little Lehner in the other wind sure has torque!

I don't know what Feigo does across their line but I feel confident in saying that at the very least, the Feigo 8XL and 10XL do not share identical coils with different magnets. Perhaps a different wind configuration with the same magnet but that would be a different motor in my mind. How will they perform on the lake? Don't know don't care. Just as long as my Hackers are faster!!!!!

Sounds like you have a smart bunch of guys behind you. I feel the same way about the Engineers who did my test. While they aren't designing motor that save people lives, they are the fastest model boaters in the world and know how to test for the best motor before they put it in the boat. They seemed to feel pretty confident in the results above and that is good enough for me.

Have you shared this data with your guys? I'd be curious to see what they think? If the test results are so skewed, how did we come up with 3 nearly identical 8XL's and 1 10XL 36% different from the 8XL's? Dumb luck?

I'd love to do some more testing as this stuff really facinates me, but I have no intentions on buying any Feigos for these tests. The ones I have were given to me and will run them in my emaxx's. Perhaps I'll drop over to Ray's some day and we'll pull a bunch off the shelf to see what we can come up with?

Thanks again for your involvement Don. I have enjoyed this thread and it's tone. I kind of feel like a grown up! I should try that more often. Keep up the good work!

Dick

[JfromJAGs]

I'm not quite sure what the background of the whole discussion is (and to be honest I don't care), but to me there is no way that the coils of the 2 Faigao's I have seen (a 8XL and a 10XL in Dick's workshop) are identical. Period.

To me the Feigao's are pretty much exact copies of the Hacker motors.

Again, what we tested was not a dyno test nor does it say anything about the performance of the motors. We just did a static IR measurment of the wires.

And the numbers make total sence:

a. they are identical to what the manufacturers say,
b. the relation of ( 10 / 8 )^2 between the motors fits perfectly

Joerg

[sneu]

Originally posted by JfromJAGs
I'm not quite sure what the background of the whole discussion is (and to be honest I don't care), but to me there is no way that the coils of the 2 Faigao's I have seen (a 8XL and a 10XL in Dick's workshop) are identical. Period.

To me the Feigao's are pretty much exact copies of the Hacker motors.

Again, what we tested was not a dyno test nor does it say anything about the performance of the motors. We just did a static IR measurment of the wires.

And the numbers make total sence:

a. they are identical to what the manufacturers say,
b. the relation of ( 10 / 8 )^2 between the motors fits perfectly

Joerg

They are different in terms of noload current and efficiency from the Hackers. The noload current is about double that of the similar Hacker.

Steve

[JfromJAGs]

This might be the case, we did'nt test it. It was not what we were looking for. We just wanted to see if a 8XL and a 10XL use different winds or not.

While having identical IR, double no load current would indeed result in quite some loss of efficiency.

Joerg

[AndyKunz]

Originally posted by Don Wollard
Really! I am not sure. Default this chat to the motor industries own engineering guidelines for such test. On Friday I received about 40 pages in the Fax from a Pal who is a respected motor engineer. Seems - from what I read in this techno-stuff a few degress variation/movement could be significant in such a test. Movement of any nature distorts the test. Whether the rotor is centered or not- it has to be locked for the test to be accurate.

Don,

Let's go back to High School Physics.

Magnetism and electricity are related to one another by a simple concept - if you change one, you cause a change in the other. If one is held still, it causes the other to be held still. Hopefully you can agree to this - it's the foundation of all motor design.

You could lock the rotor at any angle mechanically and it would have given the exact same reading. Do you believe this? (Say "YES" or you get the gong).

A DC source was applied to the windings. A DC voltage means that the electrical energy applied was constant, which means there was no change in the magnetic flux. This follows immediately from the first paragraph.

This DC source means the magnetic field created by the windings was static (after perhaps a small initial rotation).

At this point, since the magnet is no longer moving, it is no longer applying a change to the electrical field. There was some initial movement, but things were dampened (mechanically and electrically and magnetically) and we have a static condition.

Now Joerg measured the current and Dick wrote it down. No change to the electricity nor magnetism.

Only a changing field, or a moving magnet within the field, would have changed the readings. But these two items, because of the applied DC, were both static.

Since they were static, and the rotor could be locked in any position mechanically and we'd still get the same reading, we must conclude that that the readings were correct no matter what angle the rotor was held in.

The only way a change would be effected would be if the rotor were moving.

The rotor wasn't moving - it was locked in place by the magnetic field. Since no external force was applied to it, no change would be effected upon either magnetic or electrical properties.

Therefore, there is no need to lock the rotor mechanically if you want to accurately measure the resistance of the coils.

I'm sure your motor guys would agree with this. If not, please have them detail exactly where in this the laws of physics have chagned in the past few years.

Andy

[sneu]

I was also trying to figure out why they were worried about the position of the rotor. The results would be the same even if the rotor was missing! A easy way to check the resistance is to use a current limited power supply and apply say 10 amps to any 2 of the three motor leads-measure the voltage across the motor leads and you can determine the DC resistance.

Steve

[JfromJAGs]

Steve, this is exactly what we did. Except we only had a standard 13.8V power supply without current limit. So to limit the current we used a light bulb and ended at 9.2A.