Introduction: REWINDING a DC MOTOR (RS-540 Brushed Type)

About: hobby and toy grade RC car rebuilt

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.


In spanish:

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: