Best way to reduce battery consumption for LED device?
Power the LED by a small flyback converter. The current limiting resistor can eat a lot of power. Note, this schematic is only an illustration. Some design/programming work have to be done.

Something like this:







simulate this circuit &ndash; Schematic created using CircuitLab

Here is a simple model (for LTSpice IV) of the above schematic. It demonstrated efficiency of 95% and higher:

Version 4
SHEET 1 880 680
WIRE 256 -160 -288 -160
WIRE 544 -160 256 -160
WIRE 256 -32 256 -160
WIRE 544 -16 544 -160
WIRE -288 96 -288 -160
WIRE 256 128 256 48
WIRE 544 128 544 48
WIRE 544 128 256 128
WIRE 256 176 256 128
WIRE 208 256 -48 256
WIRE -48 304 -48 256
WIRE -288 416 -288 176
WIRE 256 416 256 272
WIRE -48 432 -48 384
FLAG -288 416 0
FLAG 256 416 0
FLAG -48 432 0
SYMBOL nmos 208 176 R0
SYMATTR InstName M1
SYMATTR Value IRLML2803
SYMBOL ind 240 -48 R0
SYMATTR InstName L1
SYMATTR Value 100µ
SYMATTR SpiceLine Rser=1
SYMBOL LED 560 48 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D1
SYMATTR Value NSSW008CT-P1
SYMBOL voltage -288 80 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value 5V
SYMBOL voltage -48 288 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V2
SYMATTR Value PULSE(0 4 0 10n 10n 3u 50u)
TEXT -322 456 Left 2 !.tran 1m