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Brushless gets hot

Old 09-26-2011, 08:32 AM
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phatbob02
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Default Brushless gets hot

I'm new to electric and need some help.
I'm running a GForce E400 Brushless motor with a Hobbywing Pentium 30A Brushless ESC.
I got everything connected and I ran it for about 20seconds. I noticed that the motor was pretty hot.
Is heating up normal for a brushless and if not, what am I doing wrong?

This is a pusher prop model and I'm running a APC Electric 9x6 pusher prop.

Below are the specs for my setup.

Motor specs:

KV: 1200
Battery: 3S LiPO
Max Load: 25A
Max Efficiency: 20A
Recommended Setup:
18A or 30A brushless motor ESC
2-3S LiPO and at least 1300mAh.
Prop Selection:
With 2S LiPO: 10x6, 10x8 Slow Flyer, 11x4.7 Slow Flyer
With 3S LiPO: 9x4.5, 10x5, 9x4.7 Slow Flyer

ESC specs:

1.1 Output: Continuous 30A, Burst 40A up to 10 Secs.
1.2 Input Voltage: 2-4 cells lithium battery or 5-12 cells NiCd/NIMh battery.
1.3 BEC: 2A / 5V (Linear mode).
1.4 Max Speed: 210,000rpm for 2 Poles BLM, 70,000rpm for 6 poles BLM, 35,000rpm for 12 poles BLM.
(BLM: BrushLess Motor)

Battery specs:

1800mAh Capacity
3S - 11.1 Volts - 30C Discharge

Thanks for any help,
Bob
Old 09-26-2011, 01:56 PM
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jdetray
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Default RE: Brushless gets hot

Hi Bob -

There is hot, and then there is HOT! If the motor is too hot to touch, that's bad.

Excessive heat means the motor is drawing more current than it can handle. Prolonged running at high temperatures can permanently damage the magnets, and the motor will never work properly again.

It is not unusual for motor makers to recommend props that are too large. Switching to a smaller prop will reduce the current and allow the motor to run cooler. Try a prop at the small end of the manufacturer's recommendation, or possibly a bit smaller.

Another consideration is that a motor will generally draw more current during static testing than it draws in the air. That, plus the lack of an airstream to cool the motor makes static testing very tough on motors. Don't run the motor on the bench for more than 30 seconds at a time without allowing it to cool down.

- Jeff
Old 09-27-2011, 12:37 AM
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whitecrest
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Default RE: Brushless gets hot

Also, a wattmeter will tell you how much current your setup is drawing. You can compare your measurements to the published specs and see where you stand. If your meter readings are around the maximum efficiency range for your motor, you should have no problems.
Old 09-27-2011, 01:56 AM
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phatbob02
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Default RE: Brushless gets hot

Thanks Guys!!
I'm going to try a 9x4.5 and get a friend with a wattmeter.

Bob
Old 10-03-2011, 05:02 PM
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rmenke
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Default RE: Brushless gets hot

Newbe:

Right off, this is a pusher installation, so no air is going over the motor, ESC and battery. Not to worry, you need a watt meeter to do things right anyway. Prop until you have watt draw below the rating of the moror, ESC and battery. Usually they go cheep on the ESC, so a HK turnigy pro rated around 10 more watts will do the job. There is lots of great info on the web, go to Red Schoefields "Battery Clinic" for great tips and got to know info, also Dr. Kiwi knows his stuff and lots of good info from him and others. A couple of years ago, I decided the 3D guys were having more fun,so gotta take on a new challange. After a while, the challange became affording the equipment at the rate I was killing it. A buddy started me off on the cheepie Hobby King stuff, motors, ESC's and batteries. Now, after learning to do good rolling circles I am back to some higher end stuff, but do not see much change in quality and performance. There are some 20 birds on the ceiling including AJ extras, Yacks and other "The best flyers ever". Most are very dusty as what goes to the field are a couple of RC Powers designs along with a Performanceairobatics Addiction X. What I learned to do rolling circles on and the only one of the 20 that would be replaced if I lost it. Truly a great forgiving flyer, needed whin you hit 76 like this old foggy. Maby my satisfaction with the Hobby King stuff is luck, or the fact that my last name is same as one of the HK owners. If i got into raceing and other high performance stuff, yes back to thunderpower, hacker and others. Read, read, read and ENJOY
Old 10-04-2011, 01:59 PM
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Dr Kiwi
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Default RE: Brushless gets hot

ORIGINAL: phatbob02

Thanks Guys!!
I'm going to try a 9x4.5 and get a friend with a wattmeter.

Bob

Being a 60g motor it would be unwise to push it past 180W (3W/g)... so, if your 9x4.5 draws more than about 15-16A on 3s... you'll need to reduce prop size... the 20A/25A burst rating in the quoted specs is over the top.

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