I am planning to design a LED lamp using a 6V power supply from a lead-acid battery with a rating of 4.5Ah. I want to connect 20 LEDs (LED's rating is 20mA 2V) in parallel to achieve maximum brightness. I calculated the resistor I will use is about 100 ohms to 120 ohms.
- What power rating of the resistor must I use?
- Is my calculation correct and
- what is the the current in each branch.