How good is a light on direct drive until it reaches regulated performance?

For example, a xml2 c8 on direct drive and the same c8 in regulated at 4amps. Both using the same battery ( samsung 20R )
say, if the 20R had only 50% charge left, will it still be brighter than a 50% charge regulated?
so at what percentage will it drop down to regulated level?

I’m trying to figure out if direct drive is what i should choose as an option in a light.
of course i want the brightest possible, but it does no good if its only good when fully charged or 80%.
if thats the case, then regulated seems much better because even at 40% its still gonna be same brightness right?

The regulated drive always uses some voltage up, about .1 volts. So yes the direct drive will be a little brighter.

But keep in mind a direct drive XM-L will draw a lit of current. It’s Vf is around 3.3 volts. If your cell is in very good condition you’ll be drawing close to 8 amps which will do long term damage to the LED unless it’s heatsinked very well. I’m talking direct thermal path to a copper star and that star very well heatsinked to a high mass of aluminum.

So if you care about actually using the light a regulator is a must. If it’s just a wow light that you turn on for less than a minute at a time then it’ll work. Also with such a high current draw you’ll only get maximum output for like 10 minutes before you’ve drained the battery to the point where even direct drive the output will be less than a regulated light after 10 minutes.

And the ting is output between 3 amps and 8 amps is surprisingly small because of the way LED’s have diminishing output the higher the current they’re driven.

thank you, you explained and answered my question exactly.