# Regulated vs. unregulated. What's the difference?



## rainbowbright (Aug 13, 2008)

Sorry for the unenlightened question, but I was reading an ad for a light and it says that the light will run for x amount of time on regulated output, and x amount of time on unregulated output. I assume this has to do with the type of battery, but not really sure. What's the difference?


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## CM (Aug 13, 2008)

Can you tell us what light it is?

This has been asked many times and as many answers have been given. Basically, it's marketing and there is no formal definition. To me, regulated means constant current regulated, and if you plot output vs time, the output remains constant until the battery is spent at which point the output drops rapidly. However, some people have coined the term "partially regulated" or something to that effect which to me means a voltage boost circuit. As the input voltage drops, so does the output. There are so many ways to interpret this that the term is now meaningless to me and the only way to tell for sure what the light does is to look at a plot of output vs. time. Many manufacturers are doing this now.


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## yellow (Aug 13, 2008)

regulated: output keeps the same till batts are depleted, then sudden drop, overall shorter runtime

direct: high initial brightness, immediately going heavily down on the 1st few minutes, this reduction will get less and less, but keeps on. 




ignore the names on these graphs (stolen from flashlightreviews),
the red line shows output:

regulated above





direct below


... see how there are differences in regulation and in direct also?


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## Tekno_Cowboy (Aug 14, 2008)

I would have to say that regulated just means that the power from the batteries is being altered in some form to provide whatever power to the bulb/led the designer desired. It could be to bump up the about 1.2-1.5V of a AA battery to 3.4V for an LED, or it could be to keep the brightness at a constant level for longer runtime/lower output or shorter runtime/higher output, or any number of other things.

Unregulated would be direct drive from the battery to the Bulb/LED.

In the case of some flashlights, seeing:
"3 hrs regulated, 14 hrs unregulated" would imply the use of primary batteries, and would indicate that the light output is kept constant for 3 hrs, after which the light is direct drive for 14 hrs. It could also mean that you either get 3 hrs regulated _or 14_ hrs unregulated. Your best bet would be to contact the reseller or manufactuerer for clarification.


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## Glen C (Aug 14, 2008)

Rainbow, most manufacturers mean when they state a regulated and unregulated time, that the first period is regulated ie flat consistent output as stated by yellow and tekno, then at a point where the battery voltage drops too low for the regulation device to supply a constant consistent output, the flashlight drops out of regulation and becomes unregulated and therefore has a diminishing output. One advantage of this is that the unregulated output may let you know your batteries are getting flat, if it is noticeable enough. In yellow's first graph I would very roughly describe the Fenix as in regulation for 2.5 hrs and then unregulated for another 1/2 hr.

AS CM says there is many ways to interpret things, I have seen advertisements describing Li ion incandescents as partially regulated, they are not it is just the fairly flat discharge characteristics of the battery when used with a lamp which is not taxing it too much.


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## rainbowbright (Aug 15, 2008)

OH! I get it now. Thanks guys. I thought that regulated had something to do with the battery. I now understand that it is to do with how much lumens is emitted constantly for an amount of time. It has nothing to do with the battery, but actually the flashlight.

So now that I get that, does anyone know which part of the flashlight regulates? It is the LED part (ex: SSC led, Cree led, etc), or is it some circuitry separate from the LED?


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## Gunner12 (Aug 15, 2008)

A LED is just a LED. It is a single die with phosphor and no other special circuitry in it.

In a LED flashlight, it's a separate driver circuit that determines if the light is regulated or not.


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## HKJ (Aug 15, 2008)

rainbowbright said:


> So now that I get that, does anyone know which part of the flashlight regulates? It is the LED part (ex: SSC led, Cree led, etc), or is it some circuitry separate from the LED?



It is a circuit and it is typical placed just behind the led (Very few incan lights are regulated).


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## 2xTrinity (Aug 15, 2008)

Tekno_Cowboy said:


> I would have to say that regulated just means that the power from the batteries is being altered in some form to provide whatever power to the bulb/led the designer desired. It could be to bump up the about 1.2-1.5V of a AA battery to 3.4V for an LED


A battery can be boosted (voltage step-up) or bucked (voltage step-down) without being regulated. For example, a common scheme is to simply triple battery voltage for AA lights, in order to step up ~1.2V up to the ~3.6V needed to drive the LED. The output curve will still decay with the battery discharge curve in that case.

In order for a light to be truly regulated, it must have some form of feedback -- that is a circuit that adjusts the gain of the voltage step-up, or step-down circuit based on measurement of the actual output.

Some lights are fully-regulated buck-boost, that is, they will step-up, OR step-down voltage so as to maintain constant output. Often these include low battery voltage warning features as well so that the light doesn't suddenly go dead without warning. Examples include the Liteflux LFxx series, and the Pelican 7060.

Some lights are what I would consider semi-regulated. For example, the Fenix Lights like the L0D still do drop in output as the battery voltage drops, but not as severely as in the case of a direct drive light, or "dumb booster". I haven't reverse-engineerd the circuit, but I suspect these are most likely open loop (no feedback), but still with some form of pre-programmed control based on input battery voltage

A third category is a light that is regulated, or semi-regulated to a point, then falls out of regulatoin. An example of this is a light with a buck converter (step-down regulator only), and a single LiIon cell. Whe nthe cell is fresh, the battery voltage is 4.2, and thus stepped down. Howeve,r during the runtime, the battery voltage eventually droips to the p[oint where it drops to match the LED forward voltage. Since the driver is incapable of boosting the voltage to compensate, it simply runs in direct drive thereafter.



> In the case of some flashlights, seeing:
> "3 hrs regulated, 14 hrs unregulated" would imply the use of primary batteries, and would indicate that the light output is kept constant for 3 hrs, after which the light is direct drive for 14 hrs. It could also mean that you either get 3 hrs regulated _or 14_ hrs unregulated. Your best bet would be to contact the reseller or manufactuerer for clarification.


My guess is a the first -- there would be no reason to design a light to give the option of running in an "unregulated mode". It woudl be more sensible to simply offer a lower output, but still regulated, mode.


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## jackbecker (Aug 15, 2008)

Great info. I've been trying to figure this out for a while now. Thanks!


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## toadman (Aug 16, 2008)

I had asked to explain regulated lights in a way even Homer Simpson could understand. This answer accomplished it perfectly.


kongfuchicken
03-07-2008, 01:24 PM
Well, pretend the LEDs are Homer Simpsons and the batteries are doughnut shops.

If the module is unregulated, the doughnut shop has no windows and no doors; Homer will therefore eat away most of the doughnut supply in little time and probably be on the floor eating bits and remains very quickly.

Now, imagine the doughnut shop is guarded by Apu. Homer will be forced by Apu's shogun to eat the supply at a lower rate but at the same time, in a much more consistent and predictable way. 

Now, also imagine that everytime Homer eats a doughnut, he emits a "woohoo!". Also, let us pretend that this cheerful onomatopoeia is light emitted. During the time Homer is plundering the shop with no inhibition, he'll be eating two (or more) doughnuts at a time but only emitting a single "woohoo!", thus decreasing the doughnut efficiency. While devouring in this fashion, he tends to get his head stuck inside doughnut containers (D'OH!) and this slows down his progression even further.

Outside of the analogy, the direct driven light will start off extremely bright but also very inefficient. They tend to heat themselves up, further decreasing efficiency.

Now, with Apu present, Homer is forced to eat them one at a time. But at the same time, Apu also eats a few doughnuts (far less than Homer) during the time he is servicing the shop and also decreases the efficiency a bit. That's the drawback of linear regulators which burn off a little amount of power in order to supply the consistent output.

Apu is also able to sell old stocks of doughnuts to Homer at the same price; the regulator is able to compensate for a lower voltage and provide the same output level using older batteries.

In almost every case, The presence of Apu provides benefits that far outweighs its flaws. And even though, to the naked eye, both modules will look similar at first, after a reasonable time of use, the regulated one will offer much more useful light than the unregulated one and in overall making your batteries much more well used.

Ok, that was fun!


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## TorchBoy (Aug 17, 2008)

:huh2:


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