I'm building some LED juggling balls. I'm planning to power an Arduino with two AA batteries, and power the LEDs with a 9V battery. I want to drive three of these 3W RGB LEDS in parallel, with PWM. ...
LEDs on a (battery) budget! – How can I lower the current through a LED without using up the battery?
EDIT: Here is a much brief version, the meandering motivated version is probably subsumed in the parent question on general battery life optimizations. How can I lower the current into a LED ...