LED Question (basic question...)

Greetings all -

I will apologize in advance for this question. I have a weak understanding of flashlights in general and until I bought my first "good" flashlight (a Fenix), I was buying cheap ones for me and my family that would only last a little while.

Here is my question. I bought a cheap set of 'tactical' flashlights for my brother for Christmas. He was a cheap set (basically disposable) for his work as they tend to beat them up, lose them and get 'borrowed' and never returned. So, if I dropped $30 on a light, it would be a waste.

Anyway, in the past, I would buy LED lights and from what I read, the ones I were buying were the type that continually get less and less bright. This is what I want to avoid. I am not sure what this is called, but how to I check to see that the flashlights that I have bought aren't this type?

Again, apologies in advance for not knowing these. Please be gentle...

dbirchum said:

Greetings all -

I will apologize in advance for this question. I have a weak understanding of flashlights in general and until I bought my first "good" flashlight (a Fenix), I was buying cheap ones for me and my family that would only last a little while.

Here is my question. I bought a cheap set of 'tactical' flashlights for my brother for Christmas. He was a cheap set (basically disposable) for his work as they tend to beat them up, lose them and get 'borrowed' and never returned. So, if I dropped $30 on a light, it would be a waste.

Anyway, in the past, I would buy LED lights and from what I read, the ones I were buying were the type that continually get less and less bright. This is what I want to avoid. I am not sure what this is called, but how to I check to see that the flashlights that I have bought aren't this type?

Again, apologies in advance for not knowing these. Please be gentle...

Click to expand...

I understand what you mean.

Lights that are as bright as the battery (cell) allows are direct drive, and lights that have electronics that maintain the level of brightness are called REGULATED.


Its a lot like a jockey on a horse, in a race.

The jockey could just whip the horse to full speed right out of the gate, and make the horse sprint as fast as it could....and, as the horse took off, he's be ahead of (Brighter than) the other horses....but, as he tired, the other horses, who were pacing themselves (regulated), would catch him, and, then pass him....and by the time HE reached the finish line, the other jockeys are already celebrating with super models.

So the regulation makes the light hold a level of brightness for the duration of it being on, until the cells can't support it, and it goes OFF, or, THEN drops out of regulation to act as a dimmer light, etc...

..and the UNregulated light is brighter at first, and then dies as the cell is drained.

Typically the less expensive lights won't have a constant regulated output and so as the battery voltage drops with usage so does the light output. If you can't find any literature and specifications for the light you want to buy stating that its current regulated, then it probably isn't. With lights that are regulated, the manufacturer usually makes a point to state that, as that is a good selling point.

Other points to consider when looking at the specifications for a light . . .

When the specs say that you get x lumens for y hours, you usually do not get the full x lumens for the full y hours. You get x lumens at the beginning of the y hours, and the run time is listed as the time until output drops to some lower level. The ANSI standard is 10% of stated output, but many people here seem to believe (as I do) that 50% of stated output is a better stopping point.

For that reason, output specs can be very deceiving. A direct drive light, or a light with poor regulation, will be able to list a high output (which it achieves only for the first few minutes), and a long run time (until a small percentage of the stated output is reached). The numbers will in fact misrepresent the usefulness of the light, since you will only get a brightness level that is reasonably close to what you want for short time. A regulated light, however, will state a lower output number, but that number will be truly maintained for the bulk of the stated runtime, before output starts dropping off. A regulated light may therefore report worse output/runtime numbers than an unregulated light, but the regulated light presents far more honest numbers and is far more useful. So, make sure you understand the output curves as well as the numbers. The reviews on this site are very helpful in that regard.

The situation described above is very different from a truthfully advertised "burst mode," which puts out a huge amount of light for a short period of time before output is drastically cut back. It is also very different from thermal regulation, which cuts output when the light gets too hot to prevent damage to the LED or other components.

A last issue to consider is that a higher output number could potentially mean an LED that is being overdriven, so the light will not last as long.

Good points. I've got a data logging light meter and for me the most important aspect is efficiency.........(area under the curve)..............the most amount of light over time. It doesn't have to be the brightest but all of the LED lights that I've acquired that had poor efficiency have long been sold. So for me I like well regulated and good efficiency..........and it doesn't have to be the brightest in its class.

One other thing. At the price points you are talking about, if the light is a three-cell (3 AAA, 3AA, etc.) it probably is NOT regulated. Most LEDs need between 3.5 and 4 volts to light up. That means three 1.5 volt cells. A single or double cell light will at least have a circuit to raise the voltage to the necessary level. It may or may not be regulated, but it will still be more level in output until the cells get exhausted. I personally won't even look at a three cell light at the under $30USD price point. Happy hunting and don't be afraid to ask for guidance. We're a friendly bunch around here.

BillSWPA said:

A last issue to consider (..)

Click to expand...

One more: Energy contents in a chosen battery type, voltage conversion, and a LED's light output (lumens) all have their limits. So: all things being equal, "more lumens" can be read as "more battery swapping".

All things are not equal, people use their flashlights for different jobs, and there can be such a thing as too much light. Hence regulated lights with different modes, where you can switch between how much light you want. To save battery power where possible, or go overboard when you want to amaze someone.

For multi-mode lights, you will often see a runtime specified for each mode setting. For example 3 hours @ 60 lumens, 20 hours @ 10 lumens etc, all referring to the same flashlight. If you go for such a light: don't forget to check how mode switching works on that light, and whether you think that's handy (aka User Interface).

REGULATED!!!!

Yes....that was the word I was looking for! Regulated output. Yes, that makes sense.

And thanks so much guys for being patient and not jumping over a noob for such a basic question. It means a lot.

Ok, based on all of that, I am guessing that the ones that I bought are not Regulated.

They are a "Defiant" brand and it was a 3-pack that I picked up at the Home Depot. (3-Pack 200 Lumen LED Tactical Flashlight. FL 1 Standard. 4 Hours, 170m. 3 Modes - Low, High and Strobe). That's all of the specs I can see on the package.

And, as Timothybill noted, each light takes three (3) AAA batteries (which comes with it).

Rats. I was really hoping for once to get a "regulated" flashlight for him at a price that would make sense. I guess these won't fit the bill.

Maybe I will hang on to them just for kicking around the house. They are probably not too bad lights for a non-lumen or flashoholic?

Sounds like your brother could benefit from a wrist lanyard and a holster

dbirchum said:

.............Rats. I was really hoping for once to get a "regulated" flashlight for him at a price that would make sense. I guess these won't fit the bill.

Maybe I will hang on to them just for kicking around the house. They are probably not too bad lights for a non-lumen or flashoholic?

Click to expand...

Ya, you are right. Most people wouldn't know and at least they will have something. I like to give lights as gifts especially this time of year. I feel it's my responsibility because most people don't know what they are missing out on with all the new LED technology.


Because I'm kind of picky, I don't want to give someone, something that I personally wouldn't be that excited about, it makes it hard being a flashaholic because now we're talking the more expensive lights. It's like a curse. :devil:


So it's the discounts that come around this time of year, that get me to spend so dang much money on flashlights.

dbirchum said:

REGULATED!!!!

Yes....that was the word I was looking for! Regulated output. Yes, that makes sense.

And thanks so much guys for being patient and not jumping over a noob for such a basic question. It means a lot.

Ok, based on all of that, I am guessing that the ones that I bought are not Regulated.

They are a "Defiant" brand and it was a 3-pack that I picked up at the Home Depot. (3-Pack 200 Lumen LED Tactical Flashlight. FL 1 Standard. 4 Hours, 170m. 3 Modes - Low, High and Strobe). That's all of the specs I can see on the package.

And, as Timothybill noted, each light takes three (3) AAA batteries (which comes with it).

Rats. I was really hoping for once to get a "regulated" flashlight for him at a price that would make sense. I guess these won't fit the bill.

Maybe I will hang on to them just for kicking around the house.

They are probably not too bad lights for a non-lumen or flashoholic?

Click to expand...

The only difference between the flashaholic and the less enlightened, is whether they can APPRECIATE the differences.

MOST people (Unenlightened...) only know a flashlight as this thing that casts a dim yellow circle of light with a hole in the middle, and needs to be banged once in a while because it will go out, and banging it seems to make it go on again.

LED lights are the weak shower head LED lights hanging by the check out at the parts store, that make a glow right next to you, but can't hit something 20' away, etc.

Lights get dimmer as the batteries get weaker....that's normal to them.


ANYTHING better than that is a "great light" to them.



The only two things they will NOTICE though are how far away it can hit something/the glare of the hotspot, and, how much area is lit up at once....and maybe how white the light looks compared to the yellow beams they were used to.

Unless you TOLD them it would NOT get dimmer as the cells drained, it would not occur to them...as they would just think the BATTERIES were great instead.


To impress them, a light with 1,000 lumens of flood will impress them less than a light with 100 lumens of throw. All they will perceive is that the glare from the throwy light's hot spot will make their pupils contract, will tell their brains that the light is "Bright". The evenly distributed flood of 1,000 L will be perceived as "dimmer".

About regulation.

I know of at least 4 kinds of regulation behavior - anyone know of more?

current control regulation (Like a 7135 chip driver): above the led Vf (+ overhead) the light will stay somewhat regulated, and then either drop out or dim as the battery voltage drops below Vf, depending on the circuit.

boost current control: battery V above Vf, the light will be current controlled and regulated, and below Vf the battery will be boosted until it quits, giving the "brick wall" effect where the light shuts down and your battery is toast. If V is way above Vf, it will fry from the heat.

Buck regulation: V will be lowered to Vf and the light will stay in regulation. When V drops below Vf the light quits.

Boost/Buck: The light will be fully regulated at pretty much any battery voltage - not as efficient a circuit but very versatile.

I used shorthand with the voltages - there are actually 3 to be concerned about: V batt, Vf, and V led.

schizeckinosy said:

About regulation.

I know of at least 4 kinds of regulation behavior - anyone know of more?

current control regulation (Like a 7135 chip driver): above the led Vf (+ overhead) the light will stay somewhat regulated, and then either drop out or dim as the battery voltage drops below Vf, depending on the circuit.

boost current control: battery V above Vf, the light will be current controlled and regulated, and below Vf the battery will be boosted until it quits, giving the "brick wall" effect where the light shuts down and your battery is toast. If V is way above Vf, it will fry from the heat.

Buck regulation: V will be lowered to Vf and the light will stay in regulation. When V drops below Vf the light quits.

Boost/Buck: The light will be fully regulated at pretty much any battery voltage - not as efficient a circuit but very versatile.

I used shorthand with the voltages - there are actually 3 to be concerned about: V batt, Vf, and V led.

Click to expand...

Those are at least the basic versions. PWM might count as a type and/or variation, etc.