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Old 08-17-2007, 10:23 AM   #1
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Default Brushless questions for grasshopper

I have been running brushless for some time. Time to know more about it. Please tell me what are the following answers:

What is sintered rotor?
What is the performance different on running the motors with or without the sensor?
What is the motor sensor sensing?
Why is brushless esc a lot hotter then brush esc?
What is KV?
Why the break fade out after a few laps? Is it caused ny esc too hot or the motor?
What does 3.5, 4.5, 6.5 means?
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Old 08-17-2007, 11:23 AM   #2
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Originally Posted by ioxqq View Post
What is sintered rotor?
It's a different manufacturing method of creating magnets in a desired shape. The nickel coating keeps the magnet together better. Generally sintered rotors produce more magnetic strength than a bonded rotor, and have slightly better resistance to losing magnetic strength when exposed to heat. (Although bonded rotors are still excellent, since they both use Neodymium magnets instead of Ceramic)
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Originally Posted by ioxqq View Post
What is the performance different on running the motors with or without the sensor?
Usually the only difference is slow speeds can be choppy/inacurate without the sensor. But recent speed controllers are getting better.
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What is the motor sensor sensing?
It basically lets the speed controller know the exact position of the rotor, so the speed controller knows exactly when to fire it's next burst of power to the appropriate magnet coil.
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Why is brushless esc a lot hotter then brush esc?Why the break fade out after a few laps? Is it caused ny esc too hot or the motor?
It shouldn't be hotter nor create break fade. You may have a problem. What ESC do you have, and what motor are you running?
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Originally Posted by ioxqq View Post
What is KV?
Kv is RPM's per volt with no load. However, it's only half of what determines power of a motor. Torque is the other half.

Horsepower (Watts) = RPM x Torque
746 Watts = 1 electric horsepower

Watts of power that a motor generates at 7.2V is the proper way to compare any motor. The reason you see manufacturers using Kv ratings, is because Kv ratings is easy to obtain. They are being lazy and not hooking the motor up to a Dyno with a controlled load to determine Watts of power.

Don't get caught up into using Kv ratings.
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Originally Posted by ioxqq View Post
What does 3.5, 4.5, 6.5 means?
This is the number of turns (wire loops in the electromagnet coil) used in the motor. The less the number of turns, the more electricity will flow. This causes the electromagnet coil to generate a stronger field, but at the expense of pulling more power from the battery.
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