Help! motor+esc confusion

[Belly]

I bought a RC Smart Evo.1850 brushless outrunner which is rated at a continuous current of 20 amps I think. This motor also came with a 30 Amp RC Smart ESC. I am needing to know whether they are compatible as the ESC is 30A and th motor is 20A. Please help!

[Frank Skilbeck]

Yep, ESC needs to have a higher rating than the motor. What you need to do now is select a prop that will ensure the motor doesn't pull more than 20A.

[BB]

Ditto - Aka Timbo's many articles.  Esc should where possible always exceed the motor.

[Belly]

Thanks very much! Now the motor is quoted at 1850 RPM/V and I was going to use a 9 x 4.7 slow fly prop with a 2s or 3s lipo. To go in my Piaget-epp 3d. Will this work?

[ken anderson.]

hello belly----the best way to see if 'will work' is to use a watt meter..this will tell you what the motor/prop combination is using........(it'll help you keep everything within the limit's)and save .....and as BB has stated there are load's of info on this here forum...and article's by timbo-the man himself.....

 

       ken anderson   ne 1....

[Frank Skilbeck]

The other thing you can do is run the motor (or one similar) through a programme like drivecalc (www.drivecalc.de) and it will calculate the current drawn.

 

You motor isn't in their database so I ran an  1884 kv motor and on a 9 x 4.7 prop on a 2s lipo it was pulling 22A at 8800 rpm.

 

But doing a search on you model the recommended motors are 1100 and 1400 kv with a current rating of less than 10A and recommended battery of 500 to 800 mah, so designed for a less powerful motor than you have got.

 

An 8 x 4 would pull appox 17A at over 10,000 rpm, a 7 x 4 approx 10.4A so I'd start with that and measure the current drawn

 

Note the drivecalc should just be a guide though, there's no substitute for measuring the ma current to ensure you have protected you motor, ESC and batteries.