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Other › Motor and ESC matching
11-20-2006 05:38 PM  11 years agoPost 1
Flyboy50

rrApprentice

MA - USA

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Hey guys, just want to double check something before I waste money figuring it out myself the hard way. When you buy a motor and esc, you want the esc to have a higher max amperage than the motor, right? Will the motor limit the amps itself, or do I have to mess around with the throttle limits on the tx? Thanks guys.

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11-20-2006 06:44 PM  11 years agoPost 2
stickyfox

rrKey Veteran

Rochester, NY - US

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Current is determined primarily by the motor torque. If you have the wrong motor for your setup, or something is mechanically wrong, it may draw much more current than it's supposed to. If you're experimenting with motors you should have an idea of the forces involved so you can use kT to estimate current requirements. It's always a good idea to check to see who's using what motor/ESC combo too.

Aside from that, yes, as long as the ESC is rated at higher than the motor's current, you're ok. The continuous current rating gives you a better idea of how tough an ESC is.

-fox

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11-20-2006 06:59 PM  11 years agoPost 3
JeremyZ

rrNovice

Round Lake Beach, IL - USA

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I would say that yes, you want the ESC (especially for a heli) to have some extra headroom. Depending on where/how they're mounted, it can be harder to cool a heli ESC than an airplane. Lets not kid ourselves, airplane pilots outnumber us about 50:1, so most ESCs are designed for airplanes 1st, with secondary consideration to heli usage.

I bought my ESC to handle the burst current rating of my motor *continuously*. This way, if it isn't getting quite enough cooling air, at least I know it's not about to overheat. Most ESCs assume a certain amount of airflow, which we aren't always able to supply.

As long as you're aware of this, you won't go wrong.

Another thing to consider with ESCs is the capability of the BEC. If your ESC doesn't have a switching BEC built-in, you should really consider getting a separate one. You don't want your ESC to crap out because it is so inefficient at the higher voltages you're feeding it. (built-in BECs are usually linear, and they will supply fewer & fewer servos the higher the voltage you feed to them.) Above 3S, they're pretty much useless on helis. Digital tail servos start to really load them down.

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11-20-2006 07:26 PM  11 years agoPost 4
oldfart

rrProfessor

Vancouver, Canada

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And it all relates directly, to the load the power system will be subjected to. In effect, that is determined by the rotor speed, the rotor disc area (size of blades) and the amount of collective pitch and cyclic pitch loads they will be subjected to and of course the overall weight of the helicopter.

As all electric motors are most efficient at their designed RPM it is very important to sellect the proper pinion gear, relative to the head speed you want to turn and the number of teeth on the main gear and relative to the KV (RPM per volt) rating of the motor to the Voltage rating of the battery packs you will be using.

So if you are trying to match an ESC to a motor and specific heli, I would suggest that you get advice from those using those helis giving them the info they would require: rotor blades, KV of motor, battey pack to be used (mah/voltage/C rating)and possible choice of pinion.

Then a very intelligent, money saving choice can be made.

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11-20-2006 07:37 PM  11 years agoPost 5
Flyboy50

rrApprentice

MA - USA

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Thanks guys.

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