I am working on what you could call a brake light for a car but I was having a little bit of trouble understanding how it should be powered. So, I plan to have 3 high power LEDs in series connection.
But I want at least 400 lumens per LED so the current through the series connection should be around 1 amp or more. That means that the power drawn from the battery would be 12 watts assuming a 12V battery.
If I have three LEDs with forward voltage 3V and drive current of 1 amp, that would be I need a current-limiting resistor (3V/1A) = 3 ohms. That doesn't make sense to me, obviously because a 3 ohm resistor in a circuit is uncommon. But would you rather then add no resistors at all?
A parallel connection would suck more current from the battery so for powering 3 high power LEDs, series is probably the way to go. But my approach doesn't feel right. Additionally, if I want 400+ lumens, do you think 12 watts is excessive? From the LED site I linked, it roughly is 170 lumens/watt, so about 3 watts should be good. But then from 12V you would need to draw (4W/12V) = 1/3 amps and 1/3 amps is not sufficient to meet the drive current limits of 1+amps.
I'm just really confused and I feel like I'm not optimally using the 12V battery, but anything would help, thanks!