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Need help choosing an ESC for Align 430 Brushless

Old 05-06-2011, 02:00 PM
  #1  
scoote621
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Default Need help choosing an ESC for Align 430 Brushless

Need some help, was given an align 430 brushless motor and seems to be a beast of a motor, would a 30 amp ESC be enough if powered with a 3sell battery in this motor?
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Old 05-06-2011, 04:08 PM
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Rockin Robbins
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That's not enough information. Your motor draws the number of amps necessary to turn your prop. With a smaller diameter prop or lower pitch it doesn't need as much from the battery to turn that prop up to speed. Therefore your amp draw will be low.

But if you stick a clearly ridiculous 16x8 prop on there, the motor will draw enough amps to turn that one up to speed. In the process you'll detonate your entire system, exceeding your battery's C rating, burning out your ESC and melting down the motor. Well you might get lucky and preserve some components by vaporizing others first.

But there is a range of propellers that will work for your chosen motor/battery system. The first thing you have to do is answer the question of what plane this motor is going into. How fast do you need to fly? That determines the ideal tip speed of your propeller. There are calculators and rules of thumb for this but the gold standard is multiple guess and testing to determine the winner.

Just about all motor manufacturers have data on motor RPM and amp draw for different propellers. USE THAT! I use Drive Calculator, a free download (do the Google search and it's the top choice) which lets you pick motor , speed control and propeller by manufacturer and model number for each. It will tell you the tip speed, the top speed the plane could be expected to fly given the motor/ESC/prop combination. Your actual speed will be lower due to parasitic drag from the airframe.

Drive Calculator will also let you know if the motor is drawing too many amps for the speed control or battery you'll use.

Finally, there will always be several correct solutions to every situation. You might have three props that all look good. Test them! A bunch of numbers will never be able to take the place of reality. Buy the three props and see which one you like. Buy an ESC that gives you at least a 20% safety factor on its continuous amp rating.

If you find that your system will be expected to draw 10 amps, you should buy at least a 12 amp ESC. If you want to buy a 15 or 20 amp controller you've lost nothing but a bit of a weight penalty. Too big will work fine!
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Old 05-06-2011, 04:29 PM
  #3  
kenchiroalpha
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Originally Posted by Rockin Robbins View Post
That's not enough information. Your motor draws the number of amps necessary to turn your prop. With a smaller diameter prop or lower pitch it doesn't need as much from the battery to turn that prop up to speed. Therefore your amp draw will be low.

But if you stick a clearly ridiculous 16x8 prop on there, the motor will draw enough amps to turn that one up to speed. In the process you'll detonate your entire system, exceeding your battery's C rating, burning out your ESC and melting down the motor. Well you might get lucky and preserve some components by vaporizing others first.

But there is a range of propellers that will work for your chosen motor/battery system. The first thing you have to do is answer the question of what plane this motor is going into. How fast do you need to fly? That determines the ideal tip speed of your propeller. There are calculators and rules of thumb for this but the gold standard is multiple guess and testing to determine the winner.

Just about all motor manufacturers have data on motor RPM and amp draw for different propellers. USE THAT! I use Drive Calculator, a free download (do the Google search and it's the top choice) which lets you pick motor , speed control and propeller by manufacturer and model number for each. It will tell you the tip speed, the top speed the plane could be expected to fly given the motor/ESC/prop combination. Your actual speed will be lower due to parasitic drag from the airframe.

Drive Calculator will also let you know if the motor is drawing too many amps for the speed control or battery you'll use.

Finally, there will always be several correct solutions to every situation. You might have three props that all look good. Test them! A bunch of numbers will never be able to take the place of reality. Buy the three props and see which one you like. Buy an ESC that gives you at least a 20% safety factor on its continuous amp rating.

If you find that your system will be expected to draw 10 amps, you should buy at least a 12 amp ESC. If you want to buy a 15 or 20 amp controller you've lost nothing but a bit of a weight penalty. Too big will work fine!
Hi Robbin
Once again you post excellent advice, kudos
The only thing i will add is if the OP does not have and use a Wattmeter he should invest in one as imho they are vital for this phase of the hobby
Take care dear friend
Yours Hank
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Old 05-06-2011, 05:24 PM
  #4  
Rockin Robbins
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Oops! That's a MAJOR omission of mine. You know, all the data, calculations, stories and fabrications don't mean a thing until you test YOUR system and verify that it performs according to plan.

A really cool development is the new data logging ESCs out there, the Castle Ice series and the Hobby King Super Brain series. These don't just give you a ground-based snapshot, but provide a continuous graph of throttle position, motor rpm, amp draw, battery voltage......is that it? And these numbers are collected on a living flying airframe--REAL numbers not test stand numbers.

One figure of test data is worth a roomful of calculations.
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