Fireflies pl47g2/Anduril: How to disable automatic ramping down?

Hello friends. Got my second flashlight: pl47g2. It’s pretty neat, however there’s one thing about it that really drives me nuts: After a couple of hours of use on a new battery, it will reduce brightness automatically (all the way to 2/7). If I set any brightness, in seconds it will start ramping down. Even if I just turned it on (so it’s not not overheating - i increased temp limit to no avail). Is there any way to just force it to stay on the desired level of brightness?

If you are using a battery that has been used/drained before and it already has low voltage, you will not be able to use the flashlight with full power.

Some days ago I was using my ROT66 Gen II, and the batteries were around 3.3 - 3.4V, I was using it on the max setting of ramping, but some seconds later, as the batteries drained and couldn’t hold on what the light as “needing” in terms of power, the output decreased suddenly.
That is a good thing, it helps protecting both the batteries and the flashlight.

So, independently on the amount of heat, when the battery has low voltage, the output will drop down in most of the lights.

My car is stuttering. The tank is empty, but I don’t think it should behave like this. It was fine for the last 600 km.

Thanks for replies… the same battery runs much longer on my other flashlight, so this is why I am confused. I get a couple of hours at best on big 21700 battery. I guess I have to live with it?

Not sure if the car/tank metaphor applies here, as with the flashlight I can actually turn it on to be bright, but then it goes dimmer soon. With the car it isn’t like you get smooth ride while holding the pedal. It’s either stuttering or doesn’t go. While with flashlight if switch it to high every now and then, it stays bright. But admittedly after a while I have to switch it off more often and and it goes more dim faster.

Either way… thank you

If you run your light on high or similar brightness then yes, it will drain the battery easily in a couple of hours. Sammy is right, that sounds flat out like the tank is empty.

With appropriate cooling this light should be able to completely drain a 21700 in maybe half an hour. What’s the voltage of the battery?

I typically get about 2 hours of run time on a 5000 mah battery on mine. The light stays pretty warm the whole time. The behavior you describe sounds exactly like what mine does when the battery is low. If you have a charger that will display the total mah charged to the battery you can charge one and compare the total charge to the battery capacity and see about how low it was.

Thank you friends. I came to like my X9L much more somehow for being more economical… didn’t see that coming

You can’t expect one battery to behave the same way in every flashlight. In some you could get a couple hours, in another you could get 30 min. It depends on how much power the light can hold, how efficient it is and how bright you use it at. If I understood you correctly, one of your lights is a thrower (X9L), and the other is a floody angle light (PL47). At very low battery power, the thrower will appear to have more power. But it’s the beam profile that it more useful at low power because it goes significantly further. But this is common behavior when batteries are low. As soon as you charge the battery, everything will work like new again.

EDIT: I remember when I got back into the hobby, I wanted a light that would hold for an hour like my previous light at 1300 lumens with a single battery. But I also wanted it to be 4 times brighter while still just having one battery AND I expected it to still last me an hour. Obviously I was mistaken and that is not how it works. An analogy that makes sense to me is this. If you get 400 miles out of 12 gallons of gas in a Honda Accord, you know you can’t expect 400 miles from 12 gallons if you were now driving a Corvette. Pretty much the same. Now obviously a Corvette will be funner and all that jazz, but it will have it’s trade-off, like gas mileage. Maybe not the best 2 car examples, but the X9R and PL47 are pretty opposite lights to be comparing.

Brighter lights use more power—there is no good way around it.

FF lights ramp down when heated up or low battery. Most of mine needed +15C calibration. The 660nm Emisar needed like +25-30C (since the bad linear driver overheats instantly, burning off too much voltage to go down to 2.2v for the leds)

pl47g2 has a bad linear driver, of course run time won’t compare to an efficient Buck

Thanks, that’s very in-depth and educational. I kind of see error of my thinking, and I adjusted my expectations accordingly.