Little question about lights with voltage boosting.

If I wanted to dim the output of a single AAA, AA, or anything that have a boosting circuit (or any circuitry) with a resistor. Where should I put the resistor?

Like this: (between circuit and battery)

LED - Boost Circuit - Resistor - Battery

or like this: (between circuit and LED)

LED - Resistor - Boost Circuit - Battery

Does it matter?

I assume, doing something like this will lengthen the runtime???

One problem I see (assume) with the "between circuit and battery" setup is that at some point there will not be enough power for the circuit to work. Will the boosting fail sooner than if there was no resistor? Or will this happen after a longer time?

Thanks.

The short answer is: (between circuit and LED)

LED - Resistor - Boost Circuit - Battery

However, this will only work if the circuit is a simple voltage boost only. If the circuit is a constant current driver, adding a resistor in series with the LED won't help. Since a constant current driver would just increase it's output to overcome the added resistor and maintain the current it's set for.