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Old Sep 03, 2010, 07:19 PM
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Been reading and chasing links and I think this page covers it! http://translate.google.com/translat...us12N_YY2.html

Looks like fun!
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Old Sep 06, 2010, 07:18 PM
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My fingers hurt... Go winding and re-winding and winding and re-winding... Nothing new to the winders though.

The wind linked in other post is a pretty fast sounding wind although I only hooked one up on a smaller unknown motor I had.

I wish I had some larger wire to do a 5T on the HXT750 but I practiced on it with some smaller multi strand and an 11T with some larger wire pulled from another stator. Maybe 21awg? Tried twisting it up too, leaves a lot of air room, so I guess doing it parallel works best.

Wondering what kind of amp handling goes with a smaller wire and multi strand? Does it distribute the load enough on each wire not to loose a lot on max amp draw before burning up?

Quote:
The moral is, try doing that with your pair. If you're as lucky as I was, you'll be in good shape with no further ado.
No such luck for these, but it isn't too bad.
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Old Sep 07, 2010, 01:44 AM
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Quote:
Originally Posted by Stall'n_N_Haulin View Post
My fingers hurt... Go winding and re-winding and winding and re-winding... Nothing new to the winders though.

The wind linked in other post is a pretty fast sounding wind although I only hooked one up on a smaller unknown motor I had.

I wish I had some larger wire to do a 5T on the HXT750 but I practiced on it with some smaller multi strand and an 11T with some larger wire pulled from another stator. Maybe 21awg? Tried twisting it up too, leaves a lot of air room, so I guess doing it parallel works best.

Wondering what kind of amp handling goes with a smaller wire and multi strand? Does it distribute the load enough on each wire not to loose a lot on max amp draw before burning up?


No such luck for these, but it isn't too bad.

What kv do you want?.
What propeller do you want?


My hot motor, 12 turn 1141 kv,.


Not load 2.74A, 13900,12.18V, 1141KV.

With big battery.

GWS 9x5, 10,700rpm, 21.3A, 11.23V. 239.2Watts, 69.1%, 41.5oz.

GWS 10x6, 9700rpm, 28.73A, 10.93V. 314Watts, 66.3% effy, 46.5oz.

Effy is 3% less in 12t vs 13T. same wire.
I think, 240Watts is the limit for this motor.
But with carffully throtle, 280 watts is good.

Drive calc proyected :
Graupner aeronaut 7x7e.

13,917rpm, 22.1A, 14.5V 320watts 71,7% effy.

with APC sport. 7x7.

13,420rpm, 26.3, 14.5V, 381.8watts, 71% effy.

Manuel V



Manuel V.
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Old Sep 07, 2010, 11:07 AM
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Quote:
What kv do you want?.
What propeller do you want?
Nothing certain right now. Just playing and trying to learn... which is why I wound and re-wound over and over for nothing but practice this weekend. Hence the sore fingers and classic sore fingers movie line (and broken wires), but at least the motors worked!
Waiting on eagletree to come in so I can measure and check data before I get more serious or even prop them up. Just wanted something to do/wind while I wait for more supplies to come in.

From the data you posted it sure doesn't look like much of any speed can be had as others mentioned. I'm just working with this one as its what I have at the moment. The chart of yours that jackerbes re-posted gave me enough of an idea for that wind.

I'll post what I get from the 12N10P speed wind once completed with larger wire and I can measure it. I had wound the hxt750 with a multi-strand of 26awg (12N10PYY) to see what I could fit but didn't know what it would do to the amp handling capability compared to a single larger wire, so I un-wound to wait for larger wire to come in.
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Old Sep 07, 2010, 12:56 PM
Jack
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"..Waiting on eagletree to come in so I can measure and check data..."

That gives me an opening for a questions I have about determining the Kv of a motor. When I look at an Eagle Tree graph I can use the cursor to target any point in the graph.

So when I rewound a TP 2410-12 (10T 24 AWG) and ran it up with the Eagle Tree I got the graph you see attached. I ran the motor up to half throttle or so and that is where the RPM goes to a little less than 10,000 RPM. Then I ran it up to full throttle and it went up to 17,000 RPM (yes, I was a little terrified!).

In look at it now, I realize I am seeing the pack voltage and not the voltage actually delivered to the motor. The pack voltage was 6.42V at the lower RPM and dropped to 6.25V at the higher.

So I still don't have anything here that can tell me the RPM, do I?

And what would I have to do to see the voltage at the motor?

Thanks for helping a newbie out!

Jack
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Old Sep 07, 2010, 01:30 PM
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Originally Posted by jackerbes View Post
"..Waiting on eagletree to come in so I can measure and check data..."

That gives me an opening for a questions I have about determining the Kv of a motor. When I look at an Eagle Tree graph I can use the cursor to target any point in the graph.

So when I rewound a TP 2410-12 (10T 24 AWG) and ran it up with the Eagle Tree I got the graph you see attached. I ran the motor up to half throttle or so and that is where the RPM goes to a little less than 10,000 RPM. Then I ran it up to full throttle and it went up to 17,000 RPM (yes, I was a little terrified!).

In look at it now, I realize I am seeing the pack voltage and not the voltage actually delivered to the motor. The pack voltage was 6.42V at the lower RPM and dropped to 6.25V at the higher.

So I still don't have anything here that can tell me the RPM, do I?

And what would I have to do to see the voltage at the motor?

Thanks for helping a newbie out!

Jack


First off buy the sensorless rpm sensor! It doesn't cost that much, and having the rpm logged is worth every $.

Secondly I wouldn't worry about the voltage delivered to the motor. Here's why.

Brushless motors are so entangled by the ESC, that it really makes no sense to talk about the motor as if there were no ESC's. Of course a really crummy ESC could affect motor parameters, but remember at a no-load WOT run, there really isn't a whole lot of current going to the motor anyway, so any IR drops in the ESC aren't that big of a deal.

Secondly, if you change the timing in the ESC, you will measure a different kV. So if you go to high timing, you will see an increase in rpm (also current I bet), whereas a low timing will give a lower kV. Back in the "good old days", mechanically changing the timing of a brushed motor would also change the kV of the motor, so really nothing is different with the brushless system. The resistance of the ESC will be folded into the motor winding resistance.

Finally the rpm you measure at WOT isn't exactly the kV (it will be a little lower) since there is some load on the motor due to magnetic losses and perhaps some friction from bearings and air motion. However unless you are running really high rpm for the motor, it probably is good enough for a ball park value.

If you really want to measure the motor, then measure some WOT prop loads (V, I, rpm) along with the no-load WOT measurement, and then you can enter the data into a motor program. Those programs try to take into account things like the no-load current to give you a better idea about the parameters of a ESC-motor combination.

So hope this was some help.
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Old Sep 07, 2010, 09:02 PM
Jack
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I was using the Eagle Tree Brushless RPM sensor there. That uses a pin pushed into any one of the three motor leads to determine the RPM. And it is logged as you see in the graph.

You have to tell it in setup how many magnets there are in the motor (14 in this case) so I assume that the sensor counts the power pulses and the eLogger does some math. In the data files the RPM is reported as the values see in the graph.

Eagle Tree also sells some other RPM sensors, an optical sensor and a Hall Effects sensor. Would one of those be a better choice for measuring RPM?

I took that same graph, zoomed in on five seconds of that full throttle run, and it reports an average RPM of 16,941, an average pack voltage of 6.26V, and an average current of 3.22A. The RPM and pack Volts would work out to a Kv of 2706. Is that a credible number to use as the approximate Kv for that motor? Seems awful high to me.

Jack
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Old Sep 07, 2010, 09:59 PM
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Originally Posted by jackerbes View Post
I was using the Eagle Tree Brushless RPM sensor there. That uses a pin pushed into any one of the three motor leads to determine the RPM. And it is logged as you see in the graph.

You have to tell it in setup how many magnets there are in the motor (14 in this case) so I assume that the sensor counts the power pulses and the eLogger does some math. In the data files the RPM is reported as the values see in the graph.

Eagle Tree also sells some other RPM sensors, an optical sensor and a Hall Effects sensor. Would one of those be a better choice for measuring RPM?

I took that same graph, zoomed in on five seconds of that full throttle run, and it reports an average RPM of 16,941, an average pack voltage of 6.26V, and an average current of 3.22A. The RPM and pack Volts would work out to a Kv of 2706. Is that a credible number to use as the approximate Kv for that motor? Seems awful high to me.

Jack
Jack,
I was looking at the first plot which didn't have a trace for the rpm, so I assumed you didn't have one--admittedly a dumb assumption because it would be hard to believe one wouldn't buy the rpm sensor when purchasing the Eagletree!

I think the sensorless rpm sensor is fine. I also have the optical one to use on glow engines, and it is tougher to setup--you need to be sure that it is reasonably shielded from direct sunlight. All in all if you are using a brushless motor, the sensorless pickup is the easiest to use.

With regards to you kV estimate from the measurement, I have no reason to question it. Remember the "true" kV will even be a little higher.
Alan
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Old Sep 08, 2010, 07:20 AM
Jack
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Hi Alan,

Yeah the brushless one does reduce it to a real no brainer. It is so easy to connect it and it seems pretty accurate and reliable. Before I had a DPR-100 with Hall Effect magnetic sensors and that was a bit of a nightmare set up as the sensor had to be where it could "count" the magnets at they passed and getting a location and mounting figured out was not simple.

I do get some spurious RPM spikes here and there from the brushless RPM sensor occasionally. But I think maybe those result from actions or interactions between the motor and ESC that the eLogger dutifully interprets as RPM. Thinks like the startup tones, braking forces, and maybe even the back EMF in a windmilling motor would cause things to happen that the Brushless RPM sensor might see as RPM.

It took a while to figure out that by selecting a "clean" area on the data and graphing that I can graphs without any spurious or contradictory indications.

We're sort of off topic here, I'm going to do some no load tests on a motor of a known Kv and see what I get from that. I had not thought of doing that until now.

Jack
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Old Sep 08, 2010, 07:33 PM
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Quote:
I do get some spurious RPM spikes here and there from the brushless RPM sensor occasionally.
I had the same thing on my v2. Just wrote them off like you did to the esc since they stayed consistent otherwise.
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Old Sep 09, 2010, 06:30 PM
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Jack,

As you know I have used my Eagle Tree extensively and calibrated it on prop runs using a Hobbico Optical Tach..... excellent agreement.

With Castle Phoenix ESCs you get, when connected, a constant "baseline RPM" of as much as 2000RPM or even 3300RPM... but that disappears once the motor is running. See graph below: with the motor off between runs, the "recorded RPM" stays around 3300rpm.... but if you had the motor running you could idle it down to say 500rpm and the Eagle Tree would record that faithfully.

Your determination of Kv seems okay... except that the "actual Kv" will be a bit higher than RPM/V. At no load your motor won't convert every scrap of energy into spinning the motor at the theoretical Kv... so your measured RPM will be a tiny bit less than it "should be".

Cheers, Phil
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Old Sep 09, 2010, 08:26 PM
Jack
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Thanks for the info on that Phil. I have been using a Thunderbird 18 or 54 for most of my testing and am not getting anything that weird or systematic.

The attached image is a no load test on a 2408-21 that still has the factory 1400 Kv wind on it. The two tall spikes on that were with the throttle closed and may be a tone generated by the ESC or something. But, other than those spikes I get a clean 0 at throttle closed.

If you'll notice, the pop up there says zero RPM, I generated that with my cursor on a throttle off point.

That motor has bad bearings, is running very rough and erratic, I have it as a rewind candidate. But it did run.

When I zoomed in a 15 second period on the second run seen there, I got an average RPM of 4,431 at an average voltage of 9.88V. The math on that works out to a Kv of 448 and that may have been right for as bad as it was running. Like it say, it is supposed to be a 1400 Kv motor.

I'll have to try one of my Phoenix ESCs again and see what I get. I don't remember seeing anything like you are getting in the data from the SPADET with the Phoenix 80 when I was getting some data from that.

This is my second brushless RPM sensor. I was talking to Don at Eagle Tree one time and mentioned I was having some spiking and spurious speeds issues and he sent me a more recent version (it is the V2 one) of the Brushless RPM sensor. Is that the one you are using?

Jack
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Old Sep 13, 2010, 02:48 PM
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No go on my 2 speedier wind attempts. Did the 1st with 5+4T since I was going to use 3cell if it worked out. Second I did a 4T. Don't know what's up but all I got was the jitterbug from both. On the bell magnets I used thin ca (a good bit) to tack in place for testing, was going to seal up with epoxy or jbweld if it worked.
Double checked magnets and terminations. Looked fine, even had to buy a larger soldering iron for the 20awg dual strand.
The only difference is wrapping a dual strand, but I don't know why it should matter.

Funny thing is waiting on the 20awg MD wire I did this wind 2 times on a smaller motor and it ran fine and fast on the same controllers. Had to use 2cell or it hit rpm limits around 1/2 throttle on 3cell.

I'll probably rewind with a straight 20awg and 10'ish turns. Only 15% over a standard star dlrk so I wanted fewer turns, but I want to get one to run too.
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Old Sep 13, 2010, 04:45 PM
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Found out what it was, I think, wound half of it backwards!
You end up with the same start/end on every tooth, but you need to 'mirror' the 1st three YY turns you put on the 1st six teeth, on the next six, not replicate them. Just follow the diagram on the link!
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Old Sep 13, 2010, 07:40 PM
Jack
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I'm following this and want to see if I understand it right. You're doing the 12N10P wind from the google translated link you posted up in post #796, right?

And the attached figure from that page is the completed wind with the wires grouped for a Wye termination, right?

And I'm still not sure what this wind is called. It is the Half Parallel DLRK?

Thanks for bearing with me on this.

Jack
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