# 12V DC Driver for LED Strip Light.



## samjan (Nov 22, 2011)

Hi All 
I am new CPF and have used the posts before to build a night mountain bike riding light, you guys are so helpful and seam to know the answer to everything, So hopefully you can answer this question. 

I want to drive an LED strip light from Deal Extreme SKU 81028 with a 12V Source for camping. 
This strip is not like the LED strings that seam quite common, but mounted on a metal strip.

Rated Voltage of the LED is 12V-14V, 3W, 150-200LM, working current 240mA.

Now from the reading i have done i could either run it from 1 12V battery with a resistor (but this will waste energy) so i want to use a driver to drive this from 12V. 

There are not many 12V drivers out there, the closest one i could find Deal Extreme SKU 13557 is rated at 3W but has a current of 650 - 700mA. 

So my first Question what will happen if i use this driver? 

Is there another good website were i can get the correct driver (if this one wont work). 

Also some of the drivers state 3 * 1W instead of 1 * 3W what does this mean? 

Or have i missed something critical meaning that my setup is flawed in some other way? 

Thank you in advance 

Sam

Sales Links replaced with SKU's - Norm


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## MikeAusC (Nov 22, 2011)

samjan said:


> . . . . .I want to drive an LED strip light from Deal Extreme SKU 81028 with a 12V Source for camping.
> This strip is not like the LED strings that seam quite common, but mounted on a metal strip.
> Rated Voltage of the LED is 12V-14V, 3W, 150-200LM, working current 240mA.
> Now from the reading i have done i could either run it from 1 12V battery with a resistor (but this will waste energy) so i want to use a driver to drive this from 12V.
> . . . .



These LED strips are designed to be connected DIRECTLY to a 12 volt battery. They have resistors already inside the strip.

The only reason for using an external resistor would be to dim the light.

The "12 volt" drivers are intended for driving an LED that needs 3.5 volt from a 12 volt battery.


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## samjan (Nov 22, 2011)

Thanks Mike

Was this information posted with the product and have i missed it, or is this something that you know from experience?
While i cant find the link now i do remember reading that when connected to a 12V source they only drew something like 100mA and hence were not very bright. 

So if i run them directly from 12V no protection or anything else needed? 

Thanks 

Sam


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## MikeAusC (Nov 23, 2011)

You quoted all the needed information here - 
"Rated Voltage of the LED is 12V-14V, 3W, 150-200LM, working current 240mA."


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## evilc66 (Nov 23, 2011)

Mike, you should have looked up the part number.

http://www.dealextreme.com/p/3w-3500k-200-lumen-warm-white-led-emitter-metal-strip-12-14v-81028

It's a COB linear LED. This will require a driver (or some form of current regulation) to operate safely.


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## Kinnza (Nov 23, 2011)

With a voltage rating 12-14V, it should be safe enough to try it directly wired to a 12VDC source. Of course, mounted on the heatsink. Insert an amp meter and check current draw when its hot. If past 1h it keeps working on the safe range, you could use it directly from the 12V supply, as far it is a regulated one or dont go over 12V (or either you check at max voltage bar still works on range).

If not, you will need a 12V driver, but 240mA output is not usual at all. Likely it would be easier to wire 3 in parallel to a 700mA driver (with a current mirror if their forward voltage vary enough to make current sharing too unequal. Or using an higher voltage supply (rectified halogen 12VDC PS, for example) and install a current regulator set to 240mA (a typical voltage regulator with a resistor, for constant current mode).

But trying to run it directly from 12V would be the best. In case when hot current is excessive, adding just a resistor to drop a little voltage would do the trick. But if you plan to use any kind of battery, keep in mind light output will vary as battery discharges, although you need to provide voltage rectification for the voltage at full charge. Just test the bar wired directly, there are many chances it wont need any further modification.


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## samjan (Nov 25, 2011)

Thanks Kinnza 

It seams there are mixed thoughts put there due to the lack of documentation on the product (typical deal extreme). looks like i will have to just wait till they arrive and bench test them on a heat sink. 
I will post the results when i obtain because it will hopefully help out future users. 
My intension was to run multiple lights in parallel so the 240*3 = 720mA from a 700mA driver would be ideal provided they share the current equally, a brief search returned no easily available current mirror 
so again i will just have to test them when they arrive.

I have read that changing resistors in simple led drivers can change there current output. is this easy and feasible or not worth the hassle? 

Thanks for your help so far 

Sam


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## Samy (Nov 25, 2011)

Those strip LED's are great. I run them when camping:









cheers


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## Kinnza (Nov 25, 2011)

Check this article about implementing current mirrors: http://www.ledsmagazine.com/features/6/2/2. The figures in the article are for just 2 in parallel, but it can be extended to many more, as far as the intensity (A) output is enough. It consist on just a transistor on each parallel circuit (a LED or a serial string of LEDs).

Using resistor for anything running over 150mA usually dont worth. In order to be effective, you need to compensate for several volts, resulting on high losses and/or poor regulation. Instead, use a voltage regulator on constant current mode. Still linear regulation, very simple to build, its less wasteful and allows for way more accurate current regulation. 

For any kind of linear current adjustment, you need some voltage overhead, but not large or the regulation becomes very wasteful. We can go deeper on ways of regulating the current of the bars if it result that the 12V source dont match well. Likely, it will depend more on the type of source used, specially if it voltage output has a wide range of variation or not, but I would say probably you wont need nothing or very little. Wait to the test results


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## VegasF6 (Nov 25, 2011)

I have a very similar COB strip in front of me. It's DX SKU 13190. I would bet it's identical, but who can really tell. At 12V input exactly mine measures 190 mA current draw, but then, you can't take that to mean yours will be the same. Led forward voltages vary, perhaps even more so in these no name products. Not only do they vary from product to product, but the same exact strip will have variations in current draw at a set voltage based on temperature and even time (leds have a burn in period it seems.) My model doesn't give an operating current but if I had to guess I would say it is 3S by 16P circuit. 16 chips at .020 amps each suggests .320 amps. Mine has a voltage drop of 12.8 at .32 amps. May or may not be typical.

Powering this led strip from even a fixed 12V source will not be reliable, let alone from a 12V battery. I assume you mean some sort of SLA battery, gel cell or something. You can expect charged voltage to be in the range of 13.2-13.4V (its also dependent on your charger, the health of your battery and temperature.) So ideally you will use a constant current regulator. The simplest will be a linear regulator but you have to be concerned with the voltage drop of your regulator itself. You don't have a lot of overhead. FYI a resistor will actually be just as efficient as a linear regulator and allow longer run times at full current than a linear regulator would, however it won't be as reliable and you won't have a constant output. 

Just to be clear, you are wanting this for area lighting not for your bike itself, correct? It wouldn't be anywhere near enough for bike lighting. For area lighting I imagine we could come up with some sort of driver solution, though it may be a challenge. But first, have you considered simply using an led lantern? I understand the joy of DIY but simply buying something like the Coleman exponent pack away for instance would be a much simpler solution. Otherwise, are you capable of building your own circuit? Perhaps a constant current circuit based on the LM2941. It will have a .5V dropout.

*edit*
I see now that the bike light was a prior project, my bad.


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## MikeAusC (Nov 25, 2011)

evilc66 said:


> Mike, you should have looked up the part number.
> http://www.dealextreme.com/p/3w-3500k-200-lumen-warm-white-led-emitter-metal-strip-12-14v-81028
> It's a COB linear LED. This will require a driver (or some form of current regulation) to operate safely.



Umm - DX Specifications - !!! I should know better than to believe them at face value !!

From the image, this MAY not be the conventional 12 volt LED strip with 3 LEDs and a resistor in series - it MAY be just the 3 LEDS, like some high-power arrays.

If it DOESN't have resistors under the frame, then more accurate specifications would be "12 volt - 240mA, 14 volt - 2400mA" - in which case you will need to add a series resistor, after testing with the actual supply you'll be using.

All my car interior LED lights are just 3 LEDs and a resistor in series - and they have survived well in my car for years, despite large variations in temperature and voltage.


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## samjan (Nov 25, 2011)

Samy said:


> Those strip LED's are great. I run them when camping:
> 
> 
> 
> ...



That is my intended use for the strip lights , i intend to run 3 to 4 from a 12v car battery as that is the only large power source that we will have where we camp (no mains power). 
So how are you running these lights? 
are the ones pictured infact a led strip or a string of leds? 

Cheers 

Sam


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## samjan (Nov 25, 2011)

VegasF6 said:


> I have a very similar COB strip in front of me. It's DX SKU 13190. I would bet it's identical, but who can really tell. At 12V input exactly mine measures 190 mA current draw, but then, you can't take that to mean yours will be the same. Led forward voltages vary, perhaps even more so in these no name products. Not only do they vary from product to product, but the same exact strip will have variations in current draw at a set voltage based on temperature and even time (leds have a burn in period it seems.) My model doesn't give an operating current but if I had to guess I would say it is 3S by 16P circuit. 16 chips at .020 amps each suggests .320 amps. Mine has a voltage drop of 12.8 at .32 amps. May or may not be typical.
> 
> Powering this led strip from even a fixed 12V source will not be reliable, let alone from a 12V battery. I assume you mean some sort of SLA battery, gel cell or something. You can expect charged voltage to be in the range of 13.2-13.4V (its also dependent on your charger, the health of your battery and temperature.) So ideally you will use a constant current regulator. The simplest will be a linear regulator but you have to be concerned with the voltage drop of your regulator itself. You don't have a lot of overhead. FYI a resistor will actually be just as efficient as a linear regulator and allow longer run times at full current than a linear regulator would, however it won't be as reliable and you won't have a constant output.
> 
> ...



Yes i am after area lighting, but wih a 12V car battery it may be unreliable to run 4 of these, i may have to looks into a driver and a higher voltage source. i am happy to do the project DIY i have access to alot of machining centers for housings and heatsinks but would prefer just to buy and solder the electrical components together. 
What are your thoughts on powering area lighting from a 12v led acid?


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## samjan (Nov 25, 2011)

Mike 
So the resistor in series would just regulate the current through the strip and i would choose one based on how it is behaving on the acutal batery. 
so that will limit current but not drive more through the led if it is not bright enough correct? 
and it will have the accosiated voltage drop too?


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## Samy (Nov 26, 2011)

samjan said:


> That is my intended use for the strip lights , i intend to run 3 to 4 from a 12v car battery as that is the only large power source that we will have where we camp (no mains power).
> So how are you running these lights?
> are the ones pictured infact a led strip or a string of leds?
> 
> ...



G'day mate. I didn't want to rely on the car battery so i bought a fairly inexpensive 105 amp/hr lead acid car type battery and put in a cheap battery box with a master switch and fuse and placed it in my trailer:







i have it wired to a solar regulator which is screwed to the ceiling of my camper trailer so i can charge the battery during the day. The solar regulator controls power coming to and from the battery and keeps an LCD record of solar power produce and power lost from use:












The strip rolls up into a small package. It is a 5 metre long 5050 LED waterproof strip with 60 LEDs per metre in warm white and i use a 5amp fuse and it's connected to the fuse junction, regulator then battery directly. The 5 metres uses 2.6amps and is very very bright, probably too bright for camping and i plan to fit a dimmer to it. Here it is next to my traditional camping lights which i don't use anymore:







I purchased it from here: http://www.ebay.com.au/itm/5M-5050-LED-STRIP-SMD-FlEXIBLE-300leds-Warm-White-WATERPROOF-5M-/250938920594?pt=AU_B_I_Electrical_Test_Equipment&hash=item3a6d200e92#ht_3516wt_1012


Here is my camper trailer writeup/build: http://myswag.org/forum/index.php?topic=17778.0



cheers


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## nskleddriver (Jul 4, 2012)

samjan said:


> Hi All
> I am new CPF and have used the posts before to build a night mountain bike riding light, you guys are so helpful and seam to know the answer to everything, So hopefully you can answer this question.
> 
> I want to drive an LED strip light from Deal Extreme SKU 81028 with a 12V Source for camping.
> ...


I think this is a easy question, have a very easy way to solve this problem, yours is 12V 240mA, then you can choose a led constant current power supply to drive it, for the details, you can visit our website www.nskgy.com to check your question, there's many ways to solve your problem.
Sara


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