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Old Mar 04, 2012, 09:39 AM
Team Hillbilly (UK)
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Can I ask were these motors warm or hot ?
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Old Mar 04, 2012, 09:57 AM
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Originally Posted by Aeroplayin View Post
Thanks, Space.... Your explanation was right to the point. Can you think of another reason for the high RPM knocking we experienced when they system was new? I'm curious as to why it has become a non-issue and the only time we saw it again was when we loaded the motor with the Aeronaut props during the prop testing. When the system was new, we were seeing this on Xoar and APC props as well.
I have experienced the same thing. I had to solve it by creating a slight delay in my radio on the throttle. to me, it felt like to the acceleration was too strong for the motor and esc and they were getting out of sync. it can be recreated by using a larger prop or from the ground, zero throttle to full really fast.
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Old Mar 04, 2012, 10:04 AM
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In all instances that I can think of, it was at the very beginning of an intended flight. In some instances, the problem aborted the flight. In all other instances, everything came down warm. We setup and fly our systems to the point there everything comes down warm to the touch... motor, ESC, and batteries. We never run a hot system and usually change the components of a system if we ever see heat. Flying in Florida year round, a hot system means a short lifespan.

We also fly to no less than 3.7v. Tom will usually get close to that while I’ll get a 3.75 to 3.8v reading, and batteries will recover to above 0.03v higher when allowed to recover for a few minutes. We also use between 65 and 80 percent of Ah capacity. We balance on every charge, and usually charge at about 2C. I check each individual cell with a Common Sense balancer after the battery comes off the charger, and after it comes out of the plane just to keep track of the battery dynamics. I also like to keep track of how many Ah I put back so I can adjust my flight time as batteries age. I'm pretty sure Tom does the same thing almost as often as I do.

It's strange that this has now become a non-issue on all setups. Another thing is that the Omega setup was the only motor I have seen this happen to on a power system producing less than 1200 Watts. The only other observation is that it seems to have been more severe on batteries with high discharge rates. The 65C setup seems to be the worst case of all.

But as I said, this is only an observation of a very small sample of instances.
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Old Mar 04, 2012, 10:27 AM
Team Hillbilly (UK)
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Hmmmm

Getting a clearer picture although still vague

But lets understand an ESC can not lose itself with speed - after all you are not telling it anything prior to plugging in such as is it a 900kV motor or a 2900kV motor - its just a little too crude for all that - and that goes with how much power goes in thats's just not how they work...

I think this is likely from 2 area's the motor (unwanted noise via vibrarion/rubbing distortion under load)

Or I am now beginning to think this could be a feedback problem with excessive rf noise being the issue - after all a motor is not far from a speaker design...

One way would be to add a ferrite ring if not one present - at the esc to your rx and to twist all cables going into the rx ....noise coupling in a DC circuit is bound to be an issue the more we progress into more elaborate electronic designs and usage of digital servo's - telemetry add ons...etc won't be long before we have to be running screened cables throughout our air frames.
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Old Mar 04, 2012, 10:29 AM
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Originally Posted by Aeroplayin View Post
We also use between 65 and 80 percent of Ah capacity.
I've found using 70% capacity depletes the batteries to 3.7vpc.

--Tom K.
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Old Mar 04, 2012, 12:01 PM
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I had this same squeal when going from 0 to WOT fast on a plush 60 amp ESC and a eflite 32e motor. If I advanced slow it wouldn't do it... but if I advanced it fast it would make that horrible squeal. Don't know if this is the same issue, but I changed timing to high in the ESC's programming and squeal went away. Battery was a new Eflite 4s 3200 mAh 30C.
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Old Mar 04, 2012, 01:03 PM
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Originally Posted by GetSome! View Post
I have experienced the same thing. I had to solve it by creating a slight delay in my radio on the throttle. to me, it felt like to the acceleration was too strong for the motor and esc and they were getting out of sync. it can be recreated by using a larger prop or from the ground, zero throttle to full really fast.
This is another good point. When we went from the 2S to 6S K-Force 100A ESC to the 4S to 12S HV 100A Superbrain, throttle response was inherently slight slower. But Frank never changed out his K-Force and doesn't seem to have this problem anymore either. I'd be curious to see if you changed back the throttle setting, if the issue would reemerge now that you have put some mileage on your batteries.
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Old Mar 04, 2012, 01:18 PM
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Quote:
Originally Posted by Space Bat View Post
Hmmmm

Getting a clearer picture although still vague

But lets understand an ESC can not lose itself with speed - after all you are not telling it anything prior to plugging in such as is it a 900kV motor or a 2900kV motor - its just a little too crude for all that - and that goes with how much power goes in thats's just not how they work...

I think this is likely from 2 area's the motor (unwanted noise via vibrarion/rubbing distortion under load)

Or I am now beginning to think this could be a feedback problem with excessive rf noise being the issue - after all a motor is not far from a speaker design...

One way would be to add a ferrite ring if not one present - at the esc to your rx and to twist all cables going into the rx ....noise coupling in a DC circuit is bound to be an issue the more we progress into more elaborate electronic designs and usage of digital servo's - telemetry add ons...etc won't be long before we have to be running screened cables throughout our air frames.
This makes sense, and I checked the setup and don’t see an rf ring. BUT... the K-Force did come with one, and I know we left it on when we installed it the first time. The squealing/knocking was worse with the K-Force for us. This means the timing issue was prevalent with the ring and without it. But it was better with an ESC that had a softer throttle response.

But again, as time went on, it got better anyway so I guess the only real way to see if the peak voltage on a new battery is the culprit is to buy a new battery and try it all again on a system that no longer shows the symptoms. When the Chinese start shipping product again, and the 30C 3300mAh 6S Sky Lipo batteries are back in stock, I'll do just that. But if anyone has any idea about a cause or a cure, don't hesitate to post.

Quote:
Originally Posted by bryansifsof44 View Post
I had this same squeal when going from 0 to WOT fast on a plush 60 amp ESC and a eflite 32e motor. If I advanced slow it wouldn't do it... but if I advanced it fast it would make that horrible squeal. Don't know if this is the same issue, but I changed timing to high in the ESC's programming and squeal went away. Battery was a new Eflite 4s 3200 mAh 30C.
Yes, this is what we are talking about but going from idle to WOT is fine now too. If you changed the timing back but used the same battery, I'm wondering if you could preproduce the squeal.
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Old Mar 04, 2012, 02:05 PM
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Quote:
Yes, this is what we are talking about but going from idle to WOT is fine now too. If you changed the timing back but used the same battery, I'm wondering if you could preproduce the squeal.
I'll try tonight and post what I come up with.
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Old Mar 04, 2012, 02:14 PM
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I think this will help

http://www.rcgroups.com/forums/showp...postcount=1090
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Old Mar 04, 2012, 02:33 PM
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Originally Posted by Space Bat View Post
Verrry interesting! Thanks! It was dated back in '08... when I got started in this hobby. I suppose with the new "BEC Switching" technology that really helped to kick the electric market into overdrive, probably explaining why in the past four years I've seen electric technology rise to and IMO overcome the reliability, power output, and affordability of most glow/gas powerants. I never thought I would be all electric back in '08... but now I am. Very interesting article. Thanks again!

--Tom K.
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Old Mar 04, 2012, 02:54 PM
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One thing is sure to be the case is with digital servo's onboard telemetry and more advanced switching devices and efficiency drives for better motors, batteries...Techno advances on TX and RX's etc

There will be the requirement to rethink how we wire up these planes....

After all we already have DSM2 and FHSS and other protocols which have shadowing in signal where it may be an unwanted anomaly (brown outs) which may actually be noise rather than pilot error
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Old Mar 04, 2012, 03:01 PM
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Just read this over. Good information and you should have been around the EF threads earlier why we had guys complaining about the hard start of the Torque motors. Tom, Doc, me, Frank, and almost anyone else that we can influence, runs an idle switch to overcome the startup shutter, but some still consider this a design flaw no matter what we say. This explanation clearly indicates that the better the magnet, the more probable this will be.

The only problem for me is that I'm still not making the connection with startup shutter and the knocking and squeal we get only when we are at, or near, WOT. We have sometimes initiated the idle, added throttle slowly, and then experienced the squeal at the top end only. I'll have to think about it but this post is something I can start with, so thanks for the research. I really appreciate this contribution.
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Old Mar 04, 2012, 03:14 PM
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Thats what I got... Good info, but related to startup not the squeal that I had.
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Old Mar 07, 2012, 11:20 PM
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Aeroplayin,
Ok I finally got around to testing that battery and ESC. I was still getting that horrible screech when advancing from idle to WOT, after I put the timing back to medium and low settings. It is fine on high timing. E-flite 4s 3200mAh 30C battery has 34 cycles on it.
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