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Power Pack C OVERHEATING!

#1
Just finished my fourth build. It's an FT RACER with the power pack C from flite test. I'm experiencing insane overheating. To the point that I think the ESC uses its automatic shutdown feature. I'll detail the story below, but I duplicated the result on the bench and something didn't smell right.

The power pack includes:
Emaxx GT2215/09
BL Heli 30 amp ESC
10x4.7 SF props

Anyone else having similar issues with this motor and the recommended 10x4.7 prop? Am I missing something that can save the day, or might I have a defective part? Obviously, I can drop the prop size, but I don't think it should be doing this with the recommended prop.

The story:
After balancing, checking prop rotation, and checking my CRAP, I went out for my maiden. The RACER flew great and I was quite surprised how quiet and smooth the motor/prop was. I was taking it easy since it was my first flight with this bird, and then I began to notice loss of power just past 4 minutes on my timer. I aggressively sought a safe landing but it was too late. I was suddenly aware that it was up to Ripslinger to survive. What happened next was a miracle as a spiral of death turned into a not so bad belly flop. I was elated! No repairs! I unhooked the battery and touched the Motor. Ouch! Even the mount was scalding hot. I pulled the powerpod, and the ESC was also too hot. There was no holding your finger to the unit. The 3s 2200mah turnigy battery was not hot at all.

Off to the workbench I went. I double checked the usual stuff, secured the powerpod, and fired it up. I began to notice a funny smell, so I pulled back on the throttle at about 2 minutes in. Everything was way too HOT. I decided not to push it any further.

Please help.
 

makattack

Winter is coming
Moderator
Mentor
#2
Welcome to the FT Forums!

That's very odd... that prop/motor/esc combo is within the manufacturers ratings:
http://www.emaxmodel.com/views.asp?hw_id=16

Question: have you double checked the prop is on correcly? The words/numbers facing forward? A reversed prop would be highly inefficient and might explain the overdraw...

What is the C rating of the battery pack? what throttle percentage are you flying at?
 
#3
Thanks for the reply. Odd is right!
I did check the prop. It's a 30c pack. 50-80% throttle since I had no experience with the plane. On the bench I kept it around 50% throttle.
 

quorneng

Active member
#4
If we assume the motor turns freely (does it?) then it is clearly drawing too much current.
As long as the prop really is a 10x4.7 (?) then an Emax 2215/09 motor should draw 26A on a 3S LiPo.
If the above are indeed correct then the finger points at some sort of motor fault.
This where a Watt meter would be very useful.
 
#5
It does turn freely. Sadly, I don't have a way to measure the motor draw. It is indeed a 10x4.7 prop that was included with the order from FT.
 
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AkimboGlueGuns

Biplane Guy
Mentor
#6
A 9x4.7 would probably work well. I don't really know what the deal is with the over heating for that pack specifically, but it's usually over propping that causes it.
 
#9
Balu,
I followed your advice and submitted a ticket to product support. I'll keep you all updated.

I did try a 10x6 last night, but it produced the same symptoms. Looks like the recommended prop information from EMAX is bogus, or there is a problem with the latest batch of power packs. This is not a brand new motor from EMAX by any means, but maybe something changed in the manufacturing.

I would love to know what props others have found to be successful on the EMAX GT2215/09. Texaspilot71 reported it swings an 8" prop fine.
 

Craftydan

Hostage Taker of Quads
Moderator
Mentor
#10
Troubling part of this report is I throw a 10x6 on my GT2215/09 all the time. It's been on my spitfire for nearly a year now and flown fine. I have to run a decent C-rated 3S2200 on it, with a 30A ESC, but it runs just fine.

The motors under this part designation have in past performed well, but I agree -- perhaps something has changed on the OEM side since this motor should handle the longer prop.

That being said, dropping to a 9x6 or a 10x4.7 should lower the WOT current draw from the mid-20's to the high teens. It's a workaround, and troubling that you'd have to take it. EMAX GT motors aren't the best of the best, but EMAX seemed to have put the effort in maintaining that line's quality . . . at least in past.

Edit: Ok, I see the 10x4.7 is the standard prop in the kit . . . a 9x6 will not be a drop in current from this -- they're about the same in power draw. a 9x4.7 would be the next good match down (as akimbo pointed out).
 
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#11
Looks like FT will replace the motor. Their diagnosis of bad bearings makes sense. No reason to be upset about it, because these things just happen from time to time. Wish FT wasn't caught in the middle, but such is the way of being in retail. This also reminds me of why I never rush to post a review in any store, and always take poor reviews with a grain of salt.

That being said, I'll repeat what we already know. FT is a class act. Their customer service just proved it to me, and we, the community, aren't too shabby either. Thanks for your help and suggestions.
 
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#12
I've also submitted a ticket. But I find it hard to believe we have three motors with the same problem. I will be VERY interested to hear if the new motor you receive has the same problem or if it's corrected. Hope it does!
 
#13
Yeah, it concerns me that it could be the ESC instead of the motor since you tried a second motor already. I'm tempted to pull my 30A ESC out of my Parkzone corsair to try it on the motor. That's really the last thing I want to do. I may give it a go if the new motor reacts the same as the current one.
 
#14
Sigh...I got my new motor in. I slapped a 9x4.7 on it to be on the safe side, but I quickly picked up on the familiar smell and hot motor. My accusatory finger is meandering toward the ESC. Could it be?
 
#15
So I have four or five of these motors, and I run suppo 30a esc and 10x4.5 and 10x4.7 props, never had any issues on my first three or four builds. I fly hard most of the time. I recently built and Guinean Pig on the maiden flite about 2 minutes in 50-80% throttle I started to get a glitching noise then dead no power at all, then I helplessly watched my fresh new Guinean Pig death spiral into the ground:(. On recovery of the plane one motor has flamed out burnt the ESC, burnt 6 polls in the motor, burnt the nacelle, the wing and the power pod. Took the motor into the hobby shop they warrantied it no problem, but the new motor I received is over heating the ESC. swapped motors with a know good one and no heating up. Spinning the motor it is a bit more stiff then the previous ones a have bought. I believe maybe they(EMAX) have changed bearings and the new bearings are causing a drag which will cause higher draw. Just my thoughts.
 
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#16
Scratch my last post I have something else going on with this new motor, just ran it through a cycle on a different battery and no issues. Motor is fine.
 
#17
I would strongly suspect the ESC. Brushless motors can't take straight DC. They need the ESC to generate a pulsed 3 phase signal. If the ESC has a shorted FET in the output it could be shorting part of the pulsed signal and applying DC to the windings. This would cause severe overheating. If at all possible, try another ESC.
Mike

The above description is a very simplified general statement of how a brushless motor ESC works. Fellow engineers, please don't take offense.