1 watt led

Discussion in 'The Projects Forum' started by Ducati12848, May 31, 2015.

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  1. Ducati12848

    Thread Starter New Member

    May 31, 2015
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    Main Product Spec.
    Item High Power 1W Voltage:
    3.0-3.4V
    Color Cold white Current
    250-300mA
    Material SMD LED

    Spec.

    The product model: High Power 1W LED Light

    Material: SMD LED
    Color: Cold White

    Working voltage: DC 3.0V -3.4V

    Current: 250-300mA

    LM AND T.C: 90LM-100LM/ 5800k-6500K

    IM looking to make a Light bar with these 1 watt led ..would I need a led driver or do I need to use a resistor IM lookin to probably go in a series .. IM hooking it up to a 12v car battery. IM thinking of using 36 1 watt LEDs any suggestions
     
  2. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    In series: 36*3.4=122.4 volts
    122.4 volts/12 volts=10.2 batteries

    You will need 10-11 car batteries. Good luck.
     
  3. Ducati12848

    Thread Starter New Member

    May 31, 2015
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    Yikes ... no good then ill have to figure a different opt. Ty for the speedy reply
     
  4. joeyd999

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    Jun 6, 2011
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    @shteii01 : is this a serious reply or are you just being facetious? He ask a valid question and you gave a silly answer.

    Driving 36 watts from a single 12V lead-acid battery is child's play, with multiple solutions. Why do you insist all 36 LEDs must be in series (aside from the fact that that is one of the solutions)?
     
  5. Ducati12848

    Thread Starter New Member

    May 31, 2015
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    I saw online this light bar ..
    288 Watt - 96 x 3 Watt high power LEDs in a double row array. IP67 waterproof light with 10-30VDC operating voltage range.... is there some sort of voltage regulators allows u to use that many LEDs
     
  6. Ducati12848

    Thread Starter New Member

    May 31, 2015
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    IM no Electrical engineer so YouTube and internet are my source of opts.. and the obviousness simple circuits would be only series or parallel ... any further suggestions with resources to get a better understanding bout circuits.. IM newbie so anything helps
     
  7. wayneh

    Expert

    Sep 9, 2010
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    You can use 12 parallel strings, each consisting of 3 LEDs and a resistor. The resistor will limit the current while wasting some energy. There are fancy LED drivers which could increase efficiency, but you would need 12 of them and I just wouldn't bother.

    Will the LEDs ever be on while your battery is being charged? Choose your current limiting resistors for the highest voltage the LEDs will ever see, not the nominal 12V.

    You MIGHT be able to use 9 strings of 4 LEDs, each with a lower value resistor. You'll just have to test it. There might not always be enough voltage to light the string, so be sure your test includes a "low battery" condition. Be sure you still use a resistor of at very least about 4.7Ω
     
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  8. ebeowulf17

    Active Member

    Aug 12, 2014
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    I recommend reading up a little on how LEDs work:

    https://learn.adafruit.com/all-about-leds/overview

    https://www.sparkfun.com/tutorials/219

    Then, you could use led drivers that do a lot of the tricky stuff for you and can be more efficient for high power LEDs, or go for the simple resistor current-limiting method.

    A good argument for the drivers is that they automatically deal with variations in supply voltage or differences in the forward voltage of various LEDs and make sure that the desired current runs through each LED. With the simple resistor method, seemingly small differences add up quickly. For example, 3 LEDs at 3.0V Vf powered by a 12V supply will leave 3V to drop across the resistor. If the LEDs have a 3.4V Vf, then you'd only have 1.8V to drop across the resistor, which would change your resistor calculations significantly. Unless you measure the Vf of each LED individually and adjust calculations accordingly, the resistor method leaves a wide range of error.

    Either way, the forward voltage and your supply voltage limit how many you can put in series (in this case 3.) So I think you'll want a series-parallel combination. You'd use groups of 3 LEDs in series with each other. Then, either drive each group of 3 with an appropriate LED driver OR add a series resistor to each group of 3 and then wire all of the mini-circuits (3 LEDs plus 1 resistor) in parallel.
     
    Last edited: Jun 1, 2015
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  9. ebeowulf17

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    Aug 12, 2014
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    Hmmm, I had been assuming there were driver ICs available with multiple outputs such that only 1 or 2 would be required for this project, but that might only be true for lower powered LEDs. If each group of LEDs required a separate driver, that would get rather cumbersome!
     
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  10. ebeowulf17

    Active Member

    Aug 12, 2014
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    In case the series-parallel descriptions aren't clear, here's an example:
    litlpo_SeriesParallelLEDPict.png
     
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  11. takao21203

    Distinguished Member

    Apr 28, 2012
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    <snip>

    1. Its 1W LEDs not 3W have you even read what OP wrote?
    2. Resistors are highly inappropiate for power LEDs

    The best solution is to use a boost converter and stepup to about 60 volts. This is still safe.
    Then you have several volts leeway. Dont tell me about burnout its not going to happen for several reasons. One is the inductor saturation.

    If you wish you can measure the current as well but its not really neccessary.

    You can use a 12 to 35v converter they can be hacked easily.
     
    Last edited by a moderator: Jun 1, 2015
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  12. Ducati12848

    Thread Starter New Member

    May 31, 2015
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    thanks for the replies it was my fault I tend to change directions in a blink I did start with 1w then I brought up the 3w led

    Just in case some one was wondering these were the type of LEDs I was going for they make them in 1w ..3w etc... I'll have a toggle switch but mainly be used while the vehicle is one but I'm sure I'll have use when its not one. .
     
  13. ebeowulf17

    Active Member

    Aug 12, 2014
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    Another possibility that may be helpful is LEDs with built in resistors. You don't have to do any circuit design at that point, just wire them all up in parallel with the correct polarity. You'd want to make sure they'll work properly even when fed more than 12V, like wayneh pointed out, and this is probably the least efficient solution, but I thought I'd bring it up in case ease of assembly trumps efficiency for this project.

    Here's an example (not necessarily the right ones for your project.)
    http://www.allelectronics.com/make-a-store/category/340600/leds/12-vdc-leds/1.html
     
  14. takao21203

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    Apr 28, 2012
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    Ok thanks for clearing that up.

    Actually I have both of these LEDs here.

    Its not recommended to run them at max. current, heat and shortened life cycle are two issues.

    To reduce currents and do away with the need for thick cables its also not recommended to wire them all in parallel, as well indeed you'd need equalization resistors, at least in theory.

    I have played around a lot with power LEDs, including current control, but found it unneccessary when using high voltages. The inductor will saturate at some point + will have internal resistance so the booster will not be able to crank out high currents at high voltages.

    I did 2x20W with VGA coolers, driven by a laptp brick with hacked 12/35v booster (needs different MOSFET, diode, capacitor, adj resistor).

    They did not even become warm + very bright, guess only running at 14W or so each.

    I recommend no more than 70% of full specified current, and measurement of temp. if possible. It will be 20 degree less than the chip internally, at least, so if the cooler is sizzling hot, you are doing something wrong.

    The point where the cooler becomes uncomfortable to touch is the borderline (from my experience).

    I also did measurements and tests with MOSFETs until a point where they fried (mostly shortening).

    Last not least, fuses are also recommended.
     
  15. wayneh

    Expert

    Sep 9, 2010
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    And you'll have to continue this somewhere else, since automotive topics are forbidden by the terms of service here.
     
  16. joeyd999

    AAC Fanatic!

    Jun 6, 2011
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    How is this an automotive topic? All he said was he was powering it via a car battery. Sheesh!
     
  17. takao21203

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    Apr 28, 2012
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    But 1W LEDs have no attributes at all by which they could be seen correlating to automotive.
    Neither the means of powering them from 12 volts.

    When i modify a cheap car battery charger with some 7805 + 7812 and 4mm sockets for powering CMOS IC circuits, is it automotive?

    I think posters should be a bit diplomatic when they create threads like that.

    Actually, unqualified installation of power LEDs into a vehicle is a safety risk, even if only on the margin.

    Just powering them up isnt automotive but actually installing them into a vehicle of course is. I'd recommend OP to remain quiet about it, or ask on a forum especially dealing with power LEDs, torches, LED lights DIY and modification. There are a few.
     
  18. wayneh

    Expert

    Sep 9, 2010
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    See last sentence of #13.
     
  19. takao21203

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    Apr 28, 2012
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    OK acknowledged this is a bit vague/ambiguous, on the borderline of having grammar issues.

    I'm not a moderator, dont claim to be one, just writing my opinion. I wrote my advice, using a booster and consult a LED DIY forum.
     
  20. takao21203

    Distinguished Member

    Apr 28, 2012
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    as a mod i'd probably close it as soon as it becomes clear any kind of vehicle is involved or mentioned having somethnig to do with the topic/questions raised by OP.
     
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