eFlight cub 25 - motor problem and solution

[bfeist]

Hi everyone,
Some of you witnessed the strangeness with my eFlight 25 motor at the TEMAC funfly. Thought I'd post an update.

During fight the motor would be flying along with no problem then suddenly apply a very abrupt hard brake. I thought it might be thermal cutoff.

After a successful deadstick landing back to the field, I tried restarting the motor on the ground. The motor just spazzed back and forth as though the ESC couldn't detect the orientation of the motor for startup.

At first it was suggested that the motor may have dropped a magnet and the ESC was overheating. The ESC is a Phoenix 60 (totally unnecessary given that it draws 29A static, but I had it laying around so I used it).

Given how cheap motors are now, I quickly ordered a Turnigy to replace it when I got home. I also bought some high temperature epoxy to reconnect any magnets that may have dropped.

I took apart the EFlight 25 and all the magnets were intact. No internal wear at all (what a great motor).

I tried the Phoenix 60 on another outrunner I have sitting around. It did the same thing--unable to detect the orientation.

I then put it back on the eFlight 25 and bingo, it worked. I couldn't figure out why though. Eventually it occurred to me that it might have just been a bad connection on one of the three motor wires on the ESC side. I disconnected one of the three wires for a test and throttled up gently. It did exactly what it was doing before--spazzing back and forth unable to start.

So the bottom line is that it was a bad connection on the ESC. I'm going to clean all the contacts with alcohol and examine the inside of the ESC for any loose connections.

Pretty strange one. Now I have to figure out what I'm going to do with the http://hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=7393">Turnigy motor I ordered to replace the faulty eFlight 25

Benjamin Feist - EMFSO Website Developer

[piker]

That's a really good observation, Ben.  Thanks for sharing as that could be a fairly common problem.  You're more likely to have a break at the plug end of the wire where the solder probably wicked down the wire and made it stiff, I figure.

Robert

[Tomahawk]

Sounds like a bad solder joint somewhere.  I have actually had a solder joint break where the one of the motor wires join to the wires from the windings of the motor.  Took me some time to find it as the joint was shrinkwrapped.  I have also heard of bad solder joints to bullet connectors causing this.

Chris

[DEdwards]

fyi: If anyone runs into the problem Ben has had and can't find any obvious cause with a Castle Phoenix & an outrunner (which sounds like loss of ESC/motor sycnronization), the following might help.

The senior tech guy at Castle informed me when I was talking about my Phoenix meltdown last week that Castle has recently added 2 new settings into the programming options specifically to help minimize loss of ESC/Motor syncronization problems with outrunners (I think he said larger outrunners). So you might want to compare your bios to the most recent and upgrade if needed and try to find those settings. Fortunately he says that loss of syncronization does NOT damage the controller.

But I hate to say, everytime a prop failed to start rotating and shuttered back and forth, one phase of the ESC was blown .    

[bfeist]

quote:Originally posted by byrocat

Benjamin, I'll take it off your hands if you don't have anything that it will go in to.

I'm going to be doning another trainer this winter and this looks like a good motor for that.

I'll try to make the October meeting we can send notes back and forth.....

Sorry for the delay. Dave Edwards took it off my hands--the advantage of living nearby.


Benjamin Feist - EMFSO Website Developer