View Full Version : Walkera 4#3 Stock Motor carbon brush upgrade
10-18-2008, 08:07 AM
To lengthen the life of a motor on a micro heli such as the Walkera 4#3, people tend to go to the brushless upgrade approach. However, there is a more elegant way of extending the usage time of a walkera 4#3 stock motor and this is through a carbon brush upgrade. Upgrading to a carbon brushed motor commutator extends the usage time of the stock motor and at the same time maintaining the stock weight without the extra electronic boards (pwm to ppm, escs, externaly gyro etc, 2s battery, etc) plus the motor now becomes more efficient, runs cooler, and rotates much faster.
The stock motor brushes are actually using thin copper plates which make the motor bog down after some number of flight runs.
The idea now is to replace these "copper" brushes to a much robust one which is carbon.
10-18-2008, 08:10 AM
Without having to fabricate my own carbon brush holders, i simply got the end bell of an old cp2 tail motor which uses small carbon brushes.
However the stock brushes on these motors are not designed for hi-current motors such as the stock one used on the walkera 4#3. Directly mounting these cp2 tail brushes to the walkera stock motor actually rotates the motor much slower. The approach now is 'replace' these carbon brushes from an Extreme SE180 motor replacement carbon brush spares;
But before doing that, we need to replace also the stock commutator of the walkera motor with the one with the CP2 tail motor. The stock commutator is designed to be coupled only on the copper brushes.
The commutator on the CP2 tail motor is designed for carbon brushes.
First, i removed the old commutator hub by desoldering the coil ends;
and then replaced it with the CP2 tail motor's commutator hub;
Then resoldered back the motor coils on the commutator's coil ear.
10-18-2008, 08:12 AM
Going back to the carbon brush, i isolated the SE180 carbon brush from its copper holders.
These brushes are pretty much big for the cp2 tail brush holders so i had to trim them using high speed rotating sand disc from a my dremel kit;
Triming is done by securing the carbon brush on the table with a small flat screwdriver and using the dremel rotoary sander to trim out the excess carbon;
The trimmed carbon brush are then mounted on the copper brush holders;
Make sure that the brush are properly aligned and there is enough space for motor's commutator to rotate freely;
Once everything is ok, i replaced the end bell back to the stock motor can and checked if the shaft can be rotated freely.
* I would suggest of running the motor first using external batteries (2 x AA) to allow the brushes to sit properly on the commutator and to confirm if there is no short on the soldering. (do not test the motor first on the 4-in-1 or you could burn the mosfet inside if there is a short while doing the mod).
After checking the motor if its ok, then that is the time you can mount it on the heli
frame and connect it on the 4-in-1;
Viola! Stock motor with the carbon brushes :) :) :)
and here is a test flight video using the stock motor with the upgraded carbon brushes;
Flight test Summary:
- The motor is noticeably rotating much faster as the tail is starting to trail
at hard throttle punches.
- Motor is running much cooler
10-18-2008, 08:12 AM
Here is one "Throttle Punch" the heli can do after replacing the stock motor's brushes to carbon (check first 3 seconds of the video). I almost hit the ceiling while doing the initial punch :eek:
The sound of the motor has significantly changed. You can actually compare it to the video below where it was still using the stock brush configuration.
10-18-2008, 07:53 PM
Thanks Willjames for the youtube preview tags.