LED driver question

[hyudryu]

Hey guys, I bought a cree XM-L led on ebay, and also a 3000mA driver on ebay. When i soldered it together my driver is only taking in 500mA at 4.2V


The specs for the driver:


Input Voltage: 3.7V ~ 4`2V
Output Current: 3,000mA (Max)
Modes:5(High,Middle,Low,Fast Strobe,SOS)
Diameter:16mm
Used for LED:Cree XM-L T6,XM-L2,SSC P7 etc
Application: Great for flashlight DIY.
Material: electronic components


Specs for the LED:
Available in white, 80-CRI white, 85-CRI white and 90-CRI white
ANSI-compatible chromaticity bins
Binned at 85 °C
Maximum drive current: 3000 mA
Low thermal resistance: 2.5 °C/W
Wide viewing angle: 125°
Unlimited floor life at ≤ 30 ºC/85% RH
Reflow solderable - JEDEC J-STD-020C
electrically neutral thermal path
UL-recognized component (e349212)

Size (mm x mm) 5 x 5
Maximum drive current (A) 3
Maximum power (W) 10
Light output Up to 1052 lm @ 10 W, 85°C
Typical forward voltage (V) 2.85
Viewing angle (degrees) 125
Binning 85°C, ANSI
Thermal resistance (°C/W) 2.5
Reflow-solderable Yes – JEDEC J-STD-020C-compatible
RoHS and REACH-compliant Yes
UL-recognized component Yes – Level 4 Enclosure Consideration






I have an ultrafire KF-T60 and it has a XM-L T6 led and it's super super bright, and the Led I just got is nowhere near that bright. The input voltage from the 18650 is the same as my power supply.
Now, i'm not sure how to make the LED/driver accept more current, my power supply can supply up to 16V at 3.2A, anyone have suggestions? :/

 

[Steve K]

insufficient data.

what is the power source?
what is the load on the driver? (presumably the Cree XM-L)
What is the voltage and current delivered to the load?
Is anything getting hot that shouldn't get hot? (i.e. the driver or the LED, but possibly the power source)
Pics of the test setup?
Have you put a scope on either the input or output to see if they are the nice DC waves that you expect, or maybe there is some AC stuff going on?

 

[DIWdiver]

Are you sure the driver isn't in the middle or low mode?

 

[hyudryu]

insufficient data.


what is the power source?
what is the load on the driver? (presumably the Cree XM-L)
What is the voltage and current delivered to the load?
Is anything getting hot that shouldn't get hot? (i.e. the driver or the LED, but possibly the power source)
Pics of the test setup?
Have you put a scope on either the input or output to see if they are the nice DC waves that you expect, or maybe there is some AC stuff going on?

1. DC power supply, adjustable voltage, adjustable current, looks like this: http://ecx.images-amazon.com/images/I/41eLbYZ5PVL._SY300_.jpg
2. It's taking in ~500mA max, at 3.7v
3. Voltage output from the driver measured at 3.1v, current 392mA (cycled throught the high med low strobe SOS modes to get to the high)
4. I don't have a scope all I got is my dc power supply box, and a basic multimeter

Are you sure the driver isn't in the middle or low mode?

Yeah i cycled through the 5 modes to get to high

 

[DIWdiver]

You say the input power is 3.7V. That's probably not high enough. I'd run it up a little and see if you get better results.

 

[Harold_B]

Link for the driver? Possible some other CFP user might have one on hand to test...

 

[Steve K]

thanks for the extra info.

Putting in 3.7v and asking for 3.1v out seems like it could be asking for more than some drivers can handle... i.e. not enough voltage across the driver from input to output.

Looking at the info you provided for the driver, it says that the input voltage should be between 3.7v and 4.2v. This seems like a very, very narrow range of input voltages. It makes me wonder if it is correct.. but then I generally don't have much faith in a lot of the electronics I see people buying from ebay.

Yeah.. try increasing the input voltage a bit, say a volt or two, and see what happens.

 

[hyudryu]

thanks for the extra info.

Putting in 3.7v and asking for 3.1v out seems like it could be asking for more than some drivers can handle... i.e. not enough voltage across the driver from input to output.

Looking at the info you provided for the driver, it says that the input voltage should be between 3.7v and 4.2v. This seems like a very, very narrow range of input voltages. It makes me wonder if it is correct.. but then I generally don't have much faith in a lot of the electronics I see people buying from ebay.

Yeah.. try increasing the input voltage a bit, say a volt or two, and see what happens.

I see, so as long as my output power doesn't exceed 10W, the bulb's life won't be sacraficed? Would you recommend buying a 10W led driver since my current driver isn't 3000mA as advertisedv

 

[Steve K]

I didn't comment on the bulb life... I'm just trying to help figure out why your driver isn't working as expected.

In general, I recommend working with the manufacturer or seller of the driver to figure out why it isn't working. A good manufacturer will have information available on the web that helps the customer get things up and running.

If you do buy a different driver, buy it from a source that provides support for their products.

 

[DIWdiver]

The purpose of the driver is to make the output current stable at the desired value. If you have a 3A driver, designed for a single LED, it is a 10W LED driver.

It is the responsibility of the user to make sure the LED you attach can handle the driver output, or conversely that the driver is appropriate for the LED.

If you attach a 3A driver to an LED rated at 1A, you will fry the LED very quickly. On the other hand, if you attach it to a 9A LED, you should have little trouble getting it to last a very long time.

On the other hand if you attach it to a 3A LED, it's more complicated. The XM-L is rated at 3A max. But this is only if it has a good heatsink. The more inadequate your heatsink is, the less lifetime you will get. Conversely, if you have an extraordinary heatsink, you can get acceptable lifetime at substantially higher current.

So the LED lifetime is dependent on several interrelated parameters.

 

[hyudryu]

The purpose of the driver is to make the output current stable at the desired value. If you have a 3A driver, designed for a single LED, it is a 10W LED driver.

It is the responsibility of the user to make sure the LED you attach can handle the driver output, or conversely that the driver is appropriate for the LED.

If you attach a 3A driver to an LED rated at 1A, you will fry the LED very quickly. On the other hand, if you attach it to a 9A LED, you should have little trouble getting it to last a very long time.

On the other hand if you attach it to a 3A LED, it's more complicated. The XM-L is rated at 3A max. But this is only if it has a good heatsink. The more inadequate your heatsink is, the less lifetime you will get. Conversely, if you have an extraordinary heatsink, you can get acceptable lifetime at substantially higher current.

So the LED lifetime is dependent on several interrelated parameters.

Okay well i'm still having trouble, I tried connecting the LED directly to my power supply and i set it as 3A max current but it only took 500mA. This was without the LED driver, so i'm assuming that the LED driver is capable of giving 3A output at 3.7V, but my LED is just not accepting all that current. It's strange to me because the LED is rated at 10W, so at 3.7V, it should take 2.7A and not ~500mA, I already emailed the seller and he told me he can send me a new one if I can't get it to work, but i'm afraid that the LEDs he send me will be the same

edit: I just tried powering my Xm-L T6 flashlight directly with my power supply, and it took around 300mA at 4.1v and is extremely bright, much brighter than the LED i ordered from ebay. I'm guessing it's the bulb that is extremely over rated

 

[SemiMan]

Are you sure the power supply is working correctly or that you are using it correctly? I am guessing no.

If you increase the voltage output, then the current to the LED MUST go above 500mA, assuming that you set the power supply voltage above say 4.2V.

Here is what I suggest:

1) With the power supply disconnected from the LED set the output voltage to 5V.
2) Set the power supply current to 0.
3) Connect the LED to the power supply (which I assume is on a star board and that the star board is attached to a large heat sink).
4) Slowly adjust the current upwards and observe the behaviour (watch the current meter on the power supply).

Report back to us what happens.

Semiman

 

[DIWdiver]

+1

Unless the LED has some circuitry included to limit the current, a little more voltage gets you a lot more current.

 

[The Led Machine]

Are you sure the power supply is working correctly or that you are using it correctly? I am guessing no.

If you increase the voltage output, then the current to the LED MUST go above 500mA, assuming that you set the power supply voltage above say 4.2V.

Here is what I suggest:

1) With the power supply disconnected from the LED set the output voltage to 5V.
2) Set the power supply current to 0.
3) Connect the LED to the power supply (which I assume is on a star board and that the star board is attached to a large heat sink).
4) Slowly adjust the current upwards and observe the behaviour (watch the current meter on the power supply).

Report back to us what happens.

Semiman

Agree with Semiman, I like your 4th point; make sure to do it slowly OP!