I have used li-ion cell step-up voltage to 9V in my IR gun, but the battery lasted way lower than I expected.

I suspected it may be due to combined effects of the following two:

  1. inefficiency in the step-up
  2. parasitic drain of my IR gun.
    I thought the drain was small enough, but the battery had to consume power to step-up the voltage causing overall inefficiency.

For the same reason, I think these step-down batteries may be good for med-to-high power applications, but not very good for low power applications, such as clocks and remote controllers. What are your thoughts?