Is it usually OK to use a wall-wart instead of batteries with the same voltage?

For reasons which I won't go into here, I'd like to wire this LED flashlight to use a 3V wall-wart instead of a 3V CR123A cell. Other than using a PSU with a high enough current rating (say 800mA) are there any issues with doing this?

Is replacing a battery with a wall-wart generally OK? (Provided I use the correct voltage.)

Unloaded wall 'frmrs have voltages up to or exceeding +25% higher than rated, because of poor regulation.

If you can't get 800 mA @ your desired voltage, go slightly higher and use a dropping resistor. LEDs like current sources more than they like voltage sources.

For more precision in your calculation, find the internal impedance of these cells.

A 6 watt LED on a CR123A Cell !!

Interesting they claim 5 hours.

You will need these: https://www.batteryjunction.com/rayovac-cr123a-100-box.html

CR123A is worth about 4.5 to 5.5 watt-Hrs. so if LED is 6 watts would last less then an hour. Probably operating LED at less then a watt. It would also get quite warm if run at 6 watts. Supply current is likely in 330 to 400 mA range.

Also a Luxeon LED operates at a higher voltage then a single LiIon cell can provide. They must have a voltage booster / current source supply.

The switcher boost circuitry will likely be okay with up to 5v, maybe 6vdc.