Is this regulated output?

[seeker333]

I need input from you led regulation experts out there.

Does the plot below look like 2.8 amp regulated output for a P7 emitter with 1x18650 cell?

My initial impression was that it looks like direct drive with a low voltage cut-off.

I am unsure of the effect of heating on output, but I think it would produce a drop in output, and perhaps the plot below would result.

Would this output be approximately flat if better cooling was provided?

What do you think?

Thanks for your help.

 

[Benson]

Well, you've got some heating, obviously (~10W will do that! ) and you can probably blame maybe half the falloff in the first 20-30 minutes on that, but the temperature should stabilize soon, especially on a light this size, so the continued sag is definitely absent or poor regulation -- I'd guess DD, as well, but I haven't had a DD P7 to know. Could also be buck or linear regulator, but not boost. Better cooling probably will improve it some, regardless of regulation.

Since the P7s have Vf around 3.5 V, they're commonly direct driven off one Li-ion; proper regulation to 3.5V over the range 4.2V down to 3.0V requires a buck-boost regulator, but DD is substantially cheaper, more efficient, and seemingly works well enough for most people. (I like my regulation, so I've just stayed away from the 1xLi-ion configs...)

 

[TexLite]

Looks like a "linear regulator".Unless the heatsinking is inadequate,then I wouldn't say its all heat related.

Even some DD P7 Mags do a good job of maintaining a fairly flat output after the initial drop off.

-Michael

 

[VidPro]

looks like a year of dow jones index

if HEAT of the leds was the issue, wouldnt stopping it for a half hour and running it again show you that?

there are regulators that have that kind of regulation, and there are regulators that would be more flat. it could be concidered OK, if you figure that before you RUN OUT completly it slowed down a bit, and what is the efficency of the regulator? because to get a flatline might cost more power. also your letting off a bit on the battery load , as it becomes depleated, which is often better than hitting the battery harder and harder at its weakest moments.
it looks more regulated than a DD.