High power flashlight LED lamp is 1W, want to use mobile phone battery when 4.2V is connected to electric drums!
The voltage of the LED1 watt is 3 volts and the current is 0.35 amperes. One resistor should be connected in series. The resistance is calculated as R= (4.2-3) /0.35=3.5 ohm. No series diode.
Yes. No need to connect in series. Your voltage is not enough after series connection. If you have two batteries in series, your voltage is about 6.6V. Add a resistor directly to OK. (4.2-3.3) /0.35 = 2.57 on the line. You can use 2-3 euro, at this time the current is almost between 300MA and 400MA, there is no problem.
As for the big resistance associated with rated voltage of LED bulb. Assuming the 3.3V, the 1W current is about 0.3A.The voltage on the resistor is 4.2-3.3=0.9V, the current is 0.3A, and the series resistance is about 0.9/0.3=3 ohms.Assuming LED lamp voltage rated voltage is 3V, current of about 0.33A 1W.Resistor voltage is 4.2-3=1.2V, current 0.33A, about 1.2/0.33 = 3.64 OHM Series resistor.
