Astro 3220 and HV 160 heat and other issues

[RWP]

I got both 3220 motors when Matt generously did a group buy some time ago. Both motors were ordered at the same time and just sat till now. I think they were made by the original owner.

However, I can't explain why one came with a delta termination and the other a wye termination. I set up the bike gearing thinking I had a Kv of 135 per the Astro PDF for the 3220 motor, not knowing the motors I received had a different termination and thus a different Kv.

Also the motors have a different material around the windings. The delta terminated motor has what appears to be a shiner (softer? and or more flexible?) material around the windings and the wye terminated motor appears to have a more "flat" (as in reflective) looking looking material around the windings. The material left inside each motor after the failures is different to the eye.

how much current /power was that motor taking ?
some thing pretty unusual has happened in there to force the epoxy and windings down into the rotor !!

I am thinking that for unknown reasons these motors are defective?

 

[Miles]

This motor was bought when Bob was still building them.

I have seen motors burn up (a couple of them), but I have never seen this.

It's a mystery, then..... The insulation coat on the windings still looks ok, as far as one can see.

 

[Miles]

I opened up the 3210 that I got in the group buy. The windings look exactly the same as in my other (earlier) Astro motors....

 

[liveforphysics]

I think I know why it looks like a dust-storm in your motor.

They used either an epoxy that is not stable at the temps it was reaching, or they improperly mixed the batch with the curing agent.
The windings get hot (as they should), but the epoxy expands and/or boils and/or liquefies, and creeps out between the teeth. The spinning rotor shaves the encroaching epoxy down as it spins, 1 little chunk at a time. Epoxy pieces in the flux-gap area are eventually thrown by the rotor repeatedly until they either bond firmly to something, or get tossed into the ends of the motor where the rotor can't re-fling them, so they collect.

At least that's my $0.02 guess.

 

[boostjuice]

That was my guess as well.

 

[Miles]

Sure but, that doesn't explain why Roy's motors have so much resin on the windings that they seem to be completely encapsulated within the lamination stack. Whereas usually there is an absolutely minimal amount of resin consolidating the windings.

 

[recumpence]

I have had a bunch of Astro motors and some have a large amount of that clear epoxy in them and others do not. It is strange.

At any rate, I have seen burned windings, but not this odd epoxy storm.

I tend to veer away form the idea that they were defective because the odds of two of them being faulty for the same customer and no-one else is strange indeed.

It seems that the gearing was too high. That is what cooks motors. But, why is his epoxy melting, while others get super hot and do not melt down, but rather, heat soak?

Matt

 

[Ypedal]

That clear material that goes thru the gromets.... my astro has just high temp black shrink.... it don't make sense for that much debris to come from there but that clear stuff is not high temp stuff me thinks..

 

[bigmoose]

Another possible cause is the epoxy vendor to Astro perhaps changing manufacturing locations. In the day job we just got burnt with a vendor outsourcing formulation to China for a specialized epoxy. Respected vendor (not one I have mentioned before on this board) outsourced to China and didn't tell us. Our oversight organics chemist noticed a slight change in color and did his magic reverse engineering the formulation. There were chemical changes found in it that were not advantageous to our application.

This appears to be a mis application of the potting epoxy, a mixing error, or a formulation error in the potting epoxy. I would consider this the motor manufacturer's (Astro's) problem. If they used this epoxy in their MilSpec Motors they have one h_ll of a problem in the works!

 

[drewjet]

If it helps, here is a pic of an Astro I mangaged to overtemp. As I recall it was somewhere oround 300 F with a non contact thermometer.

 

[RWP]

Thanks guys.

I am thinking of approaching Astro and would like your take and tack on this.

edit:
Why are my over temp motors shedding so much epoxy, or whatever the material is, when others are not?
There is normal friction in my drive system. The jack shaft turns freely. The rear hub/wheel turns freely. The #25 primary reduction chain is not tight nor is the BMX drive chain.
end edit.

Matt - what is the ratio for your trike and perhaps other fast 3220 machines?
Here is the ratio chart:

 

[RWP]

If it helps, here is a pic of an Astro I mangaged to overtemp. As I recall it was somewhere oround 300 F with a non contact thermometer.

Thanks drewjet,
My non contact thermometer readings were in the 230 F range.

 

[Miles]

drewjet's photo looks exactly like you'd expect a cooked motor to be like....

Maybe it needs two conditions for a motor to fail like yours?

- The high volume of resin (there's several orders of magnitude difference, here, between your delta motor and any of the Astro motors I've seen).

- Resin which is not up to the needed specification - for whatever reason.

The resin fails and the motor chokes on it without reaching a high enough temperature to cook the winding insulation or degrade the rotor.

If there was significantly less resin, it might degrade without having any effect on the motor?

 

[Miles]

To go at 39mph on the flat, you should only need the motor to put out about 3Nm.

Going up a higher than 10% slope with that gearing might cause problems....

 

[liveforphysics]

If there was significantly less resin, it might degrade without having any effect on the motor?

Less or more, more or less, it shouldn't be epoxy that goes a-travelin at temps that the motor should be well able to operate safely and continuously at. We are using some thermally conductive 280degC epoxy here at work. It's not like stuff that will stay put doesn't exist, it looks to me that this motor just didn't get high-temp epoxy.

 

[Miles]

I agree, Luke. Just trying to explain why there haven't been more failures like Roy's.

 

[RWP]

Tim said he was more or less WOT all around the track.

 

[Miles]

Here's a graph for the 3220 5t (based on the Astro spec.)

 

[SoSauty]

And DrewJet, overtemp motor looks clean. Did it perform the same afterwards? I notice power fade around 200f with 3210, so never push it further. We can get away with 300f and not kill our Astro's?

(Yep, there's not the epoxy storm, but clsoer view I see losed magnet or two.)

Hope RWP you get Astro support, if it turns out to be bum resin as it appears.

 

[etard]

Will, always trying to push the limits of your 3210, heh? :wink:

Roy,
You paid good money for that motor and Astro knows what application you are using it for so it's not like you are using it outside of the intended parameters. I would take pics from your CA and send them as proof of your power output on the bike, it might also help to have Tim ( weighs maybe 150 #s) stand next to it to show you weren't overloading the bicycle. You also recieved two differently wound motors so even if your motor failed through lack of geardown, it's still thier fault. Astro totally dropped the ball on this one, I would expect two brand new motors posted back immediately.

At least you didn't buy your motors through some Czech fly by night motor maker who's motor turned out to be a Collossal Fail.

 

[drewjet]

As you can see the magnet failed. It no longer turned. I sent it back to "Astro Bob", He fixed it for a nominal fee. I really never got much chance to run that motor, so I couldn't really comment as to a loss of power at tempature.

 

[SoSauty]

Thanks Drewjet, not much point in pushing the Astro if spiraling into thermal runaway; caution 230f to 300f temps may be fatal. I think aside from RWP's unique problem, there's 2 issues, 1) race cooling, and 2) current limiting.

RWP, that may be what happened with Tim not being used to RC electric set ups. One loses a little power and naturally feeds more amps into the motor, wahla, cooked motor Not to say that the epoxy storm isn't extreme.

Amps and motor temp was the main focus of WillowSprings prep for me. Sounds though you had perfect lowesh gearing, Tim really did sprint away and ahead of me on the track

 

[bigmoose]

I described this to a really smart guy today, his first reaction was, "Likely not a thermally cured epoxy." Thought it was another polymer that when it got hot was going above the glass transition temperature, getting non-solid and flowing. Then upon cooling was below the glass transition temperature and became solid again. The test would be to gather all those scrapings into a small beaker and heat them uniformly and see if they flow together and re-solidified upon cooling. Likely not the right material to stabilize the windings in the stator.

Paper on glass transition temperature effects: http://www.epotek.com/SSCDocs/whitepapers/Tech%20Paper%2011.pdf

 

[RWP]

edit...Astro wants to see the motors and I put them in the mail. Will let you know what they say....end edit


Hey Guys,

Thank you so much for your input!
There seems to be consensus that there was a failure of the material surrounding the windings.

I just sent off an email to Astro Flight with pics and words denoting all the issues and will let you know how they respond.

Again, I really appreciate all your help.

Roy

 

[RWP]

I had an fan idea for out runners. It's a Squirrel Cage type fan that bolts to the end of the motor can and runs over and outside of the motor can. Below are some examples of the kind of fans I am talking about. The flange face is drilled to attach to the place where a propeller would go in a Turnigy motor or it's bored out to shaft size. Has to be made to run at 6,000rpm or more...I was not able to find one that had a flat flange and was the right size to just fit over the motor can... What do you guys think?