Review on EDGELEC 180Pcs 5Mm 9 Colors X 20Pcs Assorted LED Lights Flat Lens 1.14In Long Lead + 300 Resistors (DC 6-12V) Bulb Lamps Light Emitting Diode Kit by Joseph Marshall

These can run on almost no power. Just the induction from an adjacent circuit can make it light a little if ground is shared only. That effectively is running on no power to it. With a 12v source, using 10k resistor it still is as bright as a normal led. If there is a load in parallel (relay, resistor, etc) it shunts down induction lighting and works more like a standard sensitivity led input. Super bright when using the included resistors. I've had these before and have measured that they will run on 1ma (12v with high value resistor) of power and probably last nearly forever that way. Being 3mm, their use would be for indicators and such, not lighting a larger area (of coarse).