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View Full Version : What makes a Brushless engine too hot!?


a_sprague
05-05-2007, 10:41 PM
Hi,

I am making a new brushless set up for my minimag -

Tornado 2815/2900 - 2900KV - TowerPro 30A ESC - 3c lipos. 10x7 prop.

When I set this up the engine ran very very hot and cut out at about 3/4 throttle.

Any help/advoce gratefully recieved. Thanks

rcers
05-06-2007, 01:24 AM
Several things - too much prop, too much voltage and amperage.

Prop down for starts...get a watt meter - keep it under recommended max amps and you will be fine.

Wattmeter....saves equipment

Mike

CHELLIE
05-06-2007, 02:45 AM
Yes thats too much prop for a high kv motor, get yourself a watt meter and amp meter, and see how much you are pulling, that prop is putting to much electrical strain on that motor, I would not go over a 7x5 prop, to a 8x5 prop, your motor is rated at 25 amps max, hope that helps, Chellie

http://www.conceptmodels.co.uk/tornado_2815&2825.htm

a_sprague
05-06-2007, 11:35 AM
Thanks guys,

Can using a large 3s 2250mah li-po be overloading it aswell? The engine got hot very quickly on a test run without a prop on it.

Thanks

CHELLIE
05-06-2007, 08:08 PM
Thanks guys,

Can using a large 3s 2250mah li-po be overloading it aswell? The engine got hot very quickly on a test run without a prop on it.

Thanks

yes you would be better off running that motor on a 2 cell lipo, its rated for 7 to 8 cells 8x1.2v=9.6volts your 3 cell lipo is 11.1volts

there are better motors to run with a 3 cell lipo, the 2409-12 towerpro outrunner with a 9x4.7 prop will give you about 30+oz of thrust, it comes with a 25amp esc, perfect for your 3 cell lipo and plane, your plane weighs 20oz , and with electronics about 30 to 35oz, that will give you about a 1 to 1 power ratio, take care and have fun, Chellie

https://www.unitedhobbies.com/UNITEDHOBBIES/store/comersus_viewItem.asp?idProduct=4709




https://www.unitedhobbies.com/UNITEDHOBBIES/store/comersus_listCategoriesAndProducts.asp?idCategory= 179&ParentCat=192

https://www.unitedhobbies.com/UNITEDHOBBIES/store/comersus_listCategoriesAndProducts.asp?idCategory= 184&ParentCat=59

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXNXV0&P=0

EpoweredRc
05-06-2007, 08:31 PM
Thanks guys,

Can using a large 3s 2250mah li-po be overloading it aswell? The engine got hot very quickly on a test run without a prop on it.

Thanks

I am not as smart as my father on this stuff, but Am I right or what, You should not Be running a motor without a prop on it for more then a brust... it will kill that poor motor with that HUGE battery you have there.
put you a proper prop on it and try it. the engines need some kinda cooling. if there not getting air blast then there getting Zero air cooling, thats why in a plane you make sure your motor and esc can get air. so that you wont kill them

CHELLIE
05-06-2007, 08:56 PM
Hi,

I am making a new brushless set up for my minimag -

Tornado 2815/2900 - 2900KV - TowerPro 30A ESC - 3c lipos. 10x7 prop.

When I set this up the engine ran very very hot and cut out at about 3/4 throttle.

Any help/advoce gratefully recieved. Thanks


Hi A Sprague :) if I am correct, the 2409-12 tower pro motor with a 9x4.7 prop draws 22.5 amps with a pitch speed of 43 mph, and the watts would be 11.1v x 22.5 amps for 249.75 watts, we are talking vertical performance with you minimag, you plane weighs 20 oz, AUW would be about 30 to 35 oz, or about 2 lbs , so it looks like about 125 watts per lb, that should move it real nice for you, take care,Chellie


http://www.modelflight.com.au/eflite/e-flite_article.htm

CHELLIE
05-06-2007, 08:58 PM
Dont let Foamiesrfun Fool you :) , He is Very Smart, I have learned a lot from him, Take care, Chellie

a_sprague
05-06-2007, 10:05 PM
Thanks, Chellie...think I just about understood all that!!

EpoweredRc
05-06-2007, 10:34 PM
Don't let Foamiesrfun Fool you :) , He is Very Smart, I have learned a lot from him, Take care, Chellie

I hope whatever you learned want very important stuff.:roll: :)
Don't worry a_sprague, we all were where you was at one point in time. Thats why were here, to help each other.

Taylorcraft_ASEL
05-09-2007, 02:21 AM
The only time I've ever seen a brushless engine get too hot was when the nitro content of the lipo was too high.....sorry guy, I couldn't resist!

Ken


Hi,

I am making a new brushless set up for my minimag -

Tornado 2815/2900 - 2900KV - TowerPro 30A ESC - 3c lipos. 10x7 prop.

When I set this up the engine ran very very hot and cut out at about 3/4 throttle.

Any help/advoce gratefully recieved. Thanks

Eric_N57105
06-19-2007, 09:37 PM
I am not as smart as my father on this stuff, but Am I right or what, You should not Be running a motor without a prop on it for more then a brust... it will kill that poor motor with that HUGE battery you have there.
put you a proper prop on it and try it. the engines need some kinda cooling. if there not getting air blast then there getting Zero air cooling, thats why in a plane you make sure your motor and esc can get air. so that you wont kill them

The size of the battery doesn't have anything to do with it. Chellie pointed out the problem. The voltage of the battery for this particular motor, with or without a prop, is the problem.

There is no real problem running the motor without a prop. Without a prop, there is no load on the motor, it free-runs at relatively low current.

Again, Chellie pointed out the twin problems here. A battery rated higher voltage than the motor was designed for, and a prop that loaded the motor excessively.

Eric