Hello
Have led operates from 10.5 to 12.9 volts and current up to 1.68 amp.
Should i use 2 . 2 ohm resistor to limit current so don't burn the led, or use current regulator to limit. current.
If use a current regulator use more power ( run the battery down faster) since the current regulator need power to function.
If only use 2 . 2 ohm resistor less circuit to build,
Don't know what wattage the resistor should.
Enclosed is a circuit for current limit..
Mrel

 

Should i use 2 . 2 ohm resistor to limit current so don't burn the led, or use current regulator to limit. current.

In terms of power dissipation, both will consume (waste) about the same amount of power.

It would be better if you posted the datasheet for the LED and told us what power supply voltage you plan to use (and chemistry). Will the LEDs be on constantly?

Enclosed is a circuit for current limit..

LM317 require sufficient heat sinking to be able to provide 1.5A (the guaranteed minimum). Power dissipation in the regulator and current set resistor needs to be considered.

 

The big advantage of a regulator over a resistor is the regulator can keep the current steady even as the input voltage fluctuates, you can decide if this is an issue for your situation or not. Also if there is a big discrepancy between your supply voltage and what the LED will operate on, then a buck regulator will be a lot more efficient than a linear regulator or resistor. One starting point for more info:

https://www.st.com/en/power-management/buck-current-regulators-for-led.html

 

There are plenty of 12V constant current LED drivers out there. These will be more efficient than a linear regulator or series resistor.

Bob