Originally Posted by
rapattack
Oh really i didnt know that thanks. Oh in what way does the led lighting cause interference? Do you mean one that is connected to the battery as well or a separate one? I have one that is connected to the battery but it stopped working. Dont know how long ago. I preferred to use the little ones with separate batteries as it wasnt draining my battery. So the battery is just for the motor and nothing else
LED lights achieve different brightness levels by pulsing the LED at high frequency (fast enough that you normally would not notice it - a few hundred hz probably) - this is called Pulse Width Modulation (PWM). If the LED is on half the time and off half the time very fast it look dimmer to the eye and uses half the power. The reason for this is twofold - one LEDs do not really dim linearly by reducing the current to them. PWM dimming isn't linear either but it's better. The big reason is that PWM dimming is cheap and easy to do in an efficient way. The alternative is current limiting, which either is very wasteful (dumping the extra as heat) or complex (using switch mode constant current power supplies).
Anyway, the net result is that the LEDs (pretty high power) are being switched on and off hundreds to thousands of times per second. Whenever you have power being switched on and off, radio frequency interference is generated. The higher the power, the more noise. You can shield against it but it adds weight and cost.
ebikes have this problem in spades because they also use PWM for speed control, the power levels are far higher, and the wires and coils in the motors make very efficient antennas transmitting all the noise all over the place.