Introduction: REWINDING a DC MOTOR (RS-540 Brushed Type)
REWINDING A RS-555 DC MOTOR (similar a RS-540 motor) to get much more speed in r.p.m. How to Upgrade DC Motor and Increase Speed.
The most important thing is the brushes that must be carbon-copper (metal-graphite), very important to support a large current; If they are carbon-graphite only, they will have enough resistance so they will heat up and wear out very quickly.
Step 1: This Is a 555 Slow Motor: 1100 Rpm at 7.5V
Step 2: Opening the Motor
Step 3: Rotor and Brushes
Step 4: Cutting the Windings
The winding is 160 turns and the wire is 0.25mm diameter. Once I have counted the turns of the first winding, I cut the wires of the rest of the windings.
Step 5: Winiding Diagram
Step 6: First Winding
The new wire is 0.65mm diameter and 9 turns for each winding.
Step 7: Soldering
As there are 5 poles in the rotor, between the brushes always two windings in series (18 turns) remain.
Step 8: Windings Are Finished
Step 9: Mounting the Motor
Step 10: Motor Curves: Speed (rpm)
According to the theory of operation of a DC motor, I have changed the ratio of turns of the wounds in 160/9 = 17
If you change the number of turns of the winding, no load speed (r.p.m.) and no load current and load current (A) are multiplied by the ratio (160/9 = 17): 17 * 1100 rpm = 18700 rpm 17 * 0.08 A = 1.36A
Step 11: Curve Curves: Torque
If you change the diameter of the winding wire, the no load and the no load current are same but the load current and the torque are multiplied by the ratio 0.65mm / 0.25mm = 2.6:
2,6 * 2,6 * Load Current 2,6 * Torque
Step 12: Testing the Motor
To check the result, I measure the voltage of the LiPo battery connected to the motor, no load current and the no load speed of the motor with an optical probe that obtains a ratio 1000 rpm --> 0,1 V
I have put a gear with a piece of aluminum foil reflecting light on the motor shaft.
Step 13: Measure the Speed and Voltage
Step 14: Measure the No Load Current
Step 15: Result and Explanation
The theory is fulfilled, but not exactly: we do not take into account other factors: the rotor core has losses, limit of the magnetic flux for that core, high temperature due to the increase in the current,....
160 turns ------> 9 turns
1100 rpm --------> 17000 rpm
0.08 A -----------> 1.64A
In spanish: http://reparar-cochesrc.blogspot.com/