DP-LED722b Flashlight

1) I would like to know The Lumens this Light Produces and the mA it consumes to produce that much Lumens. It is from DP (china).

2) I already have one.. I bought 2 of those..But, I want to know all the specs of it so the next time I buy a new one I know what I want exactly.

That's why I want to know the type of LED they are using and the Voltage DRop in each LED. THere are 12 Leds in it. and they claim they have 800mAH battery in it. so I wanted to know does it really produce 1 Watts output (as per their claim).. ALso, want to know the Voltage produced by that 800mAH battery and lumens..

3) I got in touch with this comapny.. I asked for their datasheet for the LED.. I am attaching along.. NOw I want to know the Total lumens produced by 1 LED. then I will know the Total Lumens produced by the 12 LEDs..

4) Can someone see the datasheet for the LED and tell me how much Lumens is produced per LED.. They claim it over all 90-100 lumens is produced per Headlamp.

http://www.docdroid.net/bkcj/green-lighting-hw5033-2.pdf.html


"LED Datasheet":http://www.docdroid.net/bkcj/green-lighting-hw5033-2.pdf.html



Can someone help me answering these questions for the LED-722b Head flashlight


SOURCE: AMAZON IMAGES BELOW:










An Outside Photo of the Box.

They look like standard 5mm LEDs. You'll get 5-10 lumens per LED at the emitter, it depends on the driver. The actual out-the-front output will be less then the emitter brightness.

LowFlux said:

They look like standard 5mm LEDs. You'll get 5-10 lumens per LED at the emitter, it depends on the driver. The actual out-the-front output will be less then the emitter brightness.

Click to expand...

Can you please elabortae how you you got to this point.. how can I check it mathematically or oractically.. did u read the datasheet..

There are 3 components to determining brightness: the LED, the driver, and the batteries. You've only provided the specs of the LED, and while you know the capacity of the battery (800mah) the documentation suggest that it has a single Nimh battery (12 hours of charging every three months doesn't sound likely to be a Lithium Ion battery) - but that is a guess.

While you can calculate how bright the LED can be hypothetically, there is no information as to what voltage the headlamp driver is providing the LEDs. The light has a driver, else it wouldn't have 2 adjustable modes. It probably has a buck driver to boost the 1.4 volts (nominal) to feed the 12 LEDs. Still no idea how much voltage the battery is providing each LED which is what your spec sheet references. The LED itself is a typical inexpensive 5mm LED with little-to-no heatsinking - from Googling around you can expect them to have at most 10 lumens each. Look around: http://www.candlepowerforums.com/vb/showthread.php?89607-White-LED-lumen-testing

Even if you were to know the forward voltage the driver provides, you will only have the brightness of the LED. Approximately 1/3rd of the brightness is lost from the emitter when measuring the out-the-front brightness - which is why CPFers put so much emphasis on OTF measurements especially when looking for a thrower light.

So you have a headlamp that will put out around 60-80 lumens of flood light - perfect for what you might need a headlamp for.

Editted to add: Looks like you got the same answer from others on another forum.

LowFlux said:

There are 3 components to determining brightness: the LED, the driver, and the batteries. You've only provided the specs of the LED, and while you know the capacity of the battery (800mah) the documentation suggest that it has a single Nimh battery (12 hours of charging every three months doesn't sound likely to be a Lithium Ion battery) - but that is a guess.

While you can calculate how bright the LED can be hypothetically, there is no information as to what voltage the headlamp driver is providing the LEDs. The light has a driver, else it wouldn't have 2 adjustable modes. It probably has a buck driver to boost the 1.4 volts (nominal) to feed the 12 LEDs. Still no idea how much voltage the battery is providing each LED which is what your spec sheet references. The LED itself is a typical inexpensive 5mm LED with little-to-no heatsinking - from Googling around you can expect them to have at most 10 lumens each. Look around: http://www.candlepowerforums.com/vb/showthread.php?89607-White-LED-lumen-testing

Even if you were to know the forward voltage the driver provides, you will only have the brightness of the LED. Approximately 1/3rd of the brightness is lost from the emitter when measuring the out-the-front brightness - which is why CPFers put so much emphasis on OTF measurements especially when looking for a thrower light.

So you have a headlamp that will put out around 60-80 lumens of flood light - perfect for what you might need a headlamp for.

Editted to add: Looks like you got the same answer from others on another forum.

Click to expand...

I got this Image from the developer I guess when I asked about the Lumens.. See it and let me know if and how far this can help in telling the exact lumens..

http://s7.postimg.org/anm19pg1n/image.jpg

Also the battery in it is 4V Lead acid battery..800mAh

I got this Image from the developer I guess when I asked about the Lumens.. See it and let me know if and how far this can help in telling the exact lumens..



Also the battery in it is 4V Lead acid battery..800mAh

LowFlux said:

There are 3 components to determining brightness: the LED, the driver, and the batteries. You've only provided the specs of the LED, and while you know the capacity of the battery (800mah) the documentation suggest that it has a single Nimh battery (12 hours of charging every three months doesn't sound likely to be a Lithium Ion battery) - but that is a guess.

While you can calculate how bright the LED can be hypothetically, there is no information as to what voltage the headlamp driver is providing the LEDs. The light has a driver, else it wouldn't have 2 adjustable modes. It probably has a buck driver to boost the 1.4 volts (nominal) to feed the 12 LEDs. Still no idea how much voltage the battery is providing each LED which is what your spec sheet references. The LED itself is a typical inexpensive 5mm LED with little-to-no heatsinking - from Googling around you can expect them to have at most 10 lumens each. Look around: http://www.candlepowerforums.com/vb/showthread.php?89607-White-LED-lumen-testing

Even if you were to know the forward voltage the driver provides, you will only have the brightness of the LED. Approximately 1/3rd of the brightness is lost from the emitter when measuring the out-the-front brightness - which is why CPFers put so much emphasis on OTF measurements especially when looking for a thrower light.

So you have a headlamp that will put out around 60-80 lumens of flood light - perfect for what you might need a headlamp for.

Editted to add: Looks like you got the same answer from others on another forum.

Click to expand...

Also, do u think this gives an accurate value mathematically for calculation of Lumens... http://www.compuphase.com/electronics/candela_lumen.htm
as in the given pocture above.. at the end in that page it says the formula is for only green leds.. other requires a weighting attached to it.. how far is it true,,

Farhaj said:

I got this Image from the developer I guess when I asked about the Lumens.. See it and let me know if and how far this can help in telling the exact lumens..

Also the battery in it is 4V Lead acid battery..800mAh

Click to expand...

Based on the stats you listed, it says 7.58 lumens. Times 12 LEDs would be 90.96 lumens.

However, this is presumably at the emitter... and if the LEDs are driven at ideal voltage.
* You could lose 1/3 of the lumens in the optic/lens/reflector.
* The LEDs may vary in lumens. It's highly unlikely every LED is 7.58 lumens. More likely that's the average. Some may be 10 lumens, some 5 lumens. Depending on how lucky you get, total lumens could vary wildly.
* it is unknown if the driver and battery are supplying the optimum power to each emitter. If they're supplying insufficient power, then the LEDs might be underdriven and producing less than their rated lumens.
* Cheap 5mm manufacturers very frequently exaggerate their numbers. It is unknown how reliable that 7.58 lumen number is.

The only way to tell for sure is to bring the light to someone with the proper equipment and have them test it. Not worth it for a cheap light like this. It would be wiser to get a better headlamp.... one with an XML in it.

Fireclaw18 said:

Based on the stats you listed, it says 7.58 lumens. Times 12 LEDs would be 90.96 lumens.

However, this is presumably at the emitter... and if the LEDs are driven at ideal voltage.
* You could lose 1/3 of the lumens in the optic/lens/reflector.
* The LEDs may vary in lumens. It's highly unlikely every LED is 7.58 lumens. More likely that's the average. Some may be 10 lumens, some 5 lumens. Depending on how lucky you get, total lumens could vary wildly.
* it is unknown if the driver and battery are supplying the optimum power to each emitter. If they're supplying insufficient power, then the LEDs might be underdriven and producing less than their rated lumens.
* Cheap 5mm manufacturers very frequently exaggerate their numbers. It is unknown how reliable that 7.58 lumen number is.

The only way to tell for sure is to bring the light to someone with the proper equipment and have them test it. Not worth it for a cheap light like this. It would be wiser to get a better headlamp.... one with an XML in it.

Click to expand...

Do you know any mathmeatical equation to calculate it out and then can vary the results with the graph..

Fireclaw18 said:

The only way to tell for sure is to bring the light to someone with the proper equipment and have them test it

Click to expand...

Farhaj said:

Do you know any mathmeatical equation to calculate it out and then can vary the results with the graph..

Click to expand...

Your reading skills could be improved, Farhaj. One can calculate when you have all the required data. In this case you don't.

In this case you have specifications, and specifications are often incorrect / unclear / exaggerated. And you have a screenshot of some test equipment, which may or may not have been measuring what you're trying to find out. As said, the only way to be sure is actually measure it (preferably in person).

And what's up with that, a lead acid battery in a headlamp? (according to box picture)

RetroTechie said:

Your reading skills could be improved, Farhaj. One can calculate when you have all the required data. In this case you don't.

In this case you have specifications, and specifications are often incorrect / unclear / exaggerated. And you have a screenshot of some test equipment, which may or may not have been measuring what you're trying to find out. As said, the only way to be sure is actually measure it (preferably in person).

And what's up with that, a lead acid battery in a headlamp? (according to box picture)

Click to expand...

Ok just mathematically is it possible to calculate out the total Amperes and watts and lumens with the data I have.. what about the formula for lumens which claims to give results if we know the mcd and other stuff..

lead acid battery 4V is inside the flashlight .. black colored one...

Farhaj said:

Ok just mathematically is it possible to calculate out the total Amperes and watts and lumens with the data I have.. what about the formula for lumens which claims to give results if we know the mcd and other stuff..

lead acid battery 4V is inside the flashlight .. black colored one...

Click to expand...

Unfortunately we can't really tell from the data you provided.

The light has a driver, which may or may not be stealing a lot of power from the LEDs. Information on that isn't available from the specs.

Furthermore, from the other specs you provided it sounds like the output of those LEDs varies wildly. Peak intensity was listed at 20k millicandela, but average was only 10k. We can't tell just from looking at specsheets the actual output of the LEDs in your unit.

Bottom line: I don't think it's possible to get a more exact answer from the specsheets you posted. It sounds like the actual output could range anywhere from 20 to 90 lumens. But if you want a more exact number you'll need to get it tested.

Note: If your light had used a more expensive LED, such as one made by CREE, then we could look at the specs for that Cree LED and give you a narrower ballpark figure for the light's output. Unfortunately, your light uses very generic 5mm LEDs, so it's not possible to do that.

Farhaj, what are you trying to get out of all of this? Letting us know what your end goal is could help you get there a lot faster.

SimulatedZero said:

Farhaj, what are you trying to get out of all of this? Letting us know what your end goal is could help you get there a lot faster.

Click to expand...

I want to know it really, so that I understand it well and get a new one with the specs and data clearly well in my mind..

so please explain..
Also, IS it true one can calculate the lumens through this formula:
Luminous flux in lumens = Radiant power (watts) x 683 lumens/watt x luminous efficacy
it says here in this LINK.: http://hyperphysics.phy-astr.gsu.edu/hbase/vision/lumpow.html
So what would be the Lumens for the LED 5mm in the specs given in the Datasheet by this forumula . can anyone help…
Datasheet: http://underwaterseaplants.awardspace.com/led.pdf

Also, I found these 3 formulas for calculating Lumens.. which one you think is reliable and work for it..

1.lm = 683 x W (Watt) x V λ


2.lm=683xluminous intensity x Radiation flux（w）


3.

There's too much unknown variation in the driver output and in the quality and output of generic 5mm LEDs.

No mathematical equation will be able to calculate with precise accuracy the output of your light from datasheets. There are too many unknown variables. What you want to do can't be done.

I want to know the Lumens output of 1 LED in the Flashlight..

I will post the schematics as well here.. if that can help more..




[/URL]
[/URL]
[/URL]
[/URL]
[/URL][/URL]

Fireclaw18 said:

There's too much unknown variation in the driver output and in the quality and output of generic 5mm LEDs.

No mathematical equation will be able to calculate with precise accuracy the output of your light from datasheets. There are too many unknown variables. What you want to do can't be done.

Click to expand...

tell me what values needs to be known for the LED CALCULATION OF LUMENS...

I will try to ask the supplier or manaufacturer..

detial me the points..

Also, I tried to calculate out the mA per LED and The total watts using the schmatics..

Can u help me with this as well..

You are going to looking at about 45 lumens of total output with all twelve LED's on, minus the losses from the reflector ~20%, which will bring the OTF Lumen output to about 39 lumens. Intensity would depend on how well the reflector focuses the light,

The unknown here is the efficiency of the driver. You would have to use a DMM to measure the power input into the circuit board and the power output from the circuit board into the LEDs. Without having a way to measure that you will have no way to more accurately estimate the lumen output.

Now, let's cover a few basics here. Perception of light output is logarithmic, not linear. This means that the visible difference between 40 and 80 lumens is less than the visible difference between 10 and 40 lumens. You have to increase the lumen output by a certain percent, not number, in order to double the perceived light output. So when you see a difference in various peoples estimates of 30 or 40 lumens (one person says 40 or 50 lumens and the other says 80), the actual difference you will see is going to be noticeable, but not incredibly so.

We can safely assume that your headlamp produces between 20 and 50 lumens at the LED. From here I am going to guess that your headlamp has maybe, MAYBE, 1000 candela. Most likely less though. (Yes, this is a complete assumption). You should get about 50ft to 75ft of real usable light and anything beyond that will be shapes and shadows. I am making this assumption from a few years experience of dealing with various lights.

Now, we roughly have an idea of what your headlamp can do, but here's the caveat to the whole thing. Even if we get 100% accurate measurements of the total output, intensity, and power draw, it won't really mean a thing. Why? Because you won't necessarily know what to do with those number. In example, if you decide to buy a headlamp that has 80 lumens and 2000 candela, roughly double your current specs, you're not going to really get a big increase in light output. This is because of human light perception being logarithmic. So, this is where simple questions about what you want out of your light come into play.

Do you want to be able to see far? (More candela)

Do you want to see more things at one time? (Floodier light, larger spot of light, more lumen out put)

Do you need it to last a very long time? (Lower power draw)

Do you need to see more things at one time and at a long distance? (More lumens AND candela)

In order to have something that completely blows your headlamp away, you would be looking at something that has about 150 lumens of output and 2000+ candela. To be honest, I think something like the Fenix HL21 (no longer produced :/) would be a solid upgrade for you. BUT, you might hate it because the beam is too narrow. So back to my earlier question, what do you want? What kind of light output are you looking for? You say you want data so you know what to buy in the future and still get what you want. So start by describing what you want and we can help you get there.