Though brushless motor is a hyped trend for rc helicopter, still number of your collection are equipped as brush motors. Don’ t be sad, here is a guide to increase the power and efficiency of your brush motors by breaking-in.
The whole concept is easy to understand, is to wear the square shape of brushes into round shape under a low-voltage, no-load situation.
And the process will be happened in this way. Start the motor with less than 1/2 operating voltage for 1-2 hours, and break-in the motor by make it spin in the direction as it will turn. By connecting 2 alkaline AA cell in series and let it run dry, there will be enough electricity for the motor mods.
Problems on Stock Brushed Motors
Since most of the heat comes from the resistance of carbon soot which is non conductive. This imply energy waste on heat instead of power of your heli. The carbon buildup is also the cause of the dropping fight times. There is even cases reported that it could result in burn-out to ESC or battery by causing current spikes.
The arcing in motor concentrate on the small area of brush, which causes heat that in turns increase the resistance of carbon brushes. Also, creates microscopic pits on commutator and brush, and this enlarges the problem. Obviously, this shorten the lifespan and power of motor, the heat generated may even fuse the brushes to commutator.
Advantages of Breaking in Motors
This trick enable the brush contact with commutator over a wider area, thus enhance the motor power through reducing the motor resistance. Also, reduce resistance and arcing between bushes and commutator with the wider contact area. Even helps on the situations like microscopic pitting, excessive carbon soot buildup and excessive heat. Overall, these offers you a motor with longer life span, more efficient and reliable, draw current stably, yet makes your battery last longer as well.
Water Break in and Dry Break in
Don’ t worry, water break in won’t make the motor short circuit. Otherwise there would not be such thing. Some rumor claim that water break in result in a higher performance than dry break in, but it still need more proof.
Advantages of water break in
- Reduce pitting by motor arcing
- Cool the motor down
- Wash away carbon buildup
- Difficult to clean out water completely
- Water may left inside motors and corrode
Please note that water break in is only refer to distilled water without other substance or mixture in it.
There are other motor break in methods which are not that popular. For example, rubbing alcohol on motor to keep the temperature low. Though it shares the similar advantage as water and alcohol itself evaporate easily, so that get rid of the hard to dry up problem. But don’t forget it is flammable, so be careful in it’s your choice.
Besides these, there is ice break in, it could help when you run the motor at larger than 1/2 operating voltage.
Break-in Procedure
Prepare 2 alkaline AA’s for 2-3s lipo / 6-8 NiMH or NiCD; or 1 AA for smaller batteries. Put the AA in series, then connect to the leads of motor and make sure the connection make the rotation spin in the same way on the rc heli. Wait until the motor run out of battery, of course you can make this with the heat-sink. But if you are dealing with the tail motor of micro helicopter, better run it not more than 90 minutes.
If you want to try wet break in, then you have to put the motor(not batteries or any other components) under water. When it get done, you may dry it with compress air. Remember not to take the motor apart, as this will dislocate the components. Add little bit oil for preventing rust.
Someone completed the break in and here is the result:
For example my n30 motors for the rear tail rotor drew 0.07 A when I first started breaking them in. After they were done breaking in they only drew 0.02A, and it’s the same situation with the main 370 motor on a 300 sized heli. No load before break-in they draw about 3 to 4 times the current as no load after break-in. This could also be a good way to tell if a motor has been broken in or not.
Maybe you will ask “Can I just do the break in by running the motor at low throttle without take it apart from the model?”
It sounds similar, but there is differences. As ESC may delivers short bursts of full pack voltage, which cause arcing that pit the commutator and make a worse result.
credit to mrasmm
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