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Pumpkin drop event

help understanding ESC's

sundown57

Well-known member
#1
Ok so I bought 4 cheap esc's from china and all 4 set on fire. So now I need to buy new ones. I also bought 4 Emax 2212 II 900 KV motors . it says on the package it only draws 9.5 amps with a 10.45 prop. To me, that doesn't sound right. I burnt up a 30 amp ESC with a 2200 kv motor and a 6-inch prop. on eBay I see some brushless ESC with only 2 wires going to the receiver and some with 3. So can anyone tell me what would be a nice but cheap esc ? do i need 3 wires or will the ones with 2 work. and what amp should I go for? Thanks
 

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FDS

Well-known member
#2
At 2200kv you are making at least twice as much current draw than at 900. Big props spun slow draw less amps, like a big diesel chugging along, it makes a lot of low down grunt without sucking gas.
I like the Skywalker and Hobbyking esc’s. Get fixed wing ones, many eBay ones are for multi rotors, you will smoke any ESC if you try to run a too fast motor with a steep pitch or an over large prop.
 
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Fidget

Active member
#3
I assume you're building an airplane rather than a quad.

The 3 wires suggests that they have a battery elimination circuit (BEC) built in. You want that to provide 5V power to your receiver and servos. Be sure whatever ESC you buy has that.

Buy at least a 20Amp ESC for that setup. Also pay attention to the battery connector it comes with unless you want to solder a new one.

Hobbyking sells Turnigy Plush ESCs that I've been happy with. Otherwise I would go with Emax. Better to spend a little more and get in the air morning reliably at this point. And Emax is available from several places.
 

FDS

Well-known member
#6
Yeah, that’s the ones mentioned by @Fidget. Nice truck. I bet that could tow a small planet!
I don’t mind sacrificing a little extra weight in the ESC in exchange for having plenty of Bec power and not much heat in the ESC.
 

sundown57

Well-known member
#7
Yeah, that’s the ones mentioned by @Fidget. Nice truck. I bet that could tow a small planet!
I don’t mind sacrificing a little extra weight in the ESC in exchange for having plenty of Bec power and not much heat in the ESC.
ok. just bought 3 of them. thank you all again for the help.
 

Merv

Well-known member
#9
It would be a good idea to get and use a watt meter.

There is a relationship between Kv & prop size. With motors of similar amp rating, the higher Kv motor will use smaller diameter props. If you put a large diameter prop on a high Kv motor, you will increase the amp draw. Something will eventually burn out, either the ESC or the motor.

As @Fidget said, 3 wires on the Rx plug of an ESC means it has a built in BEC. The 2 wire version aka as opto, will not have a BEC. They are generally used in quad applications. With all applications, you only want 1 BEC. This will avoid the potential of multiple BEC fighting each other. One calling for higher voltage and one calling for lower voltage.