Need Help with 5 LEDs one driver
- Thread starter stinggray
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LEDs you linked to need between 13.5-15v and the powersupply only puts out 12v. Thats no good
Do some more research and pay attention to the specs
Let me see if I got this right. With a 60 watt driver putting out 12v wired parallel to three 20 watt-12v LED's or Six 10 watt-12v LED's will work correctly?
Gryloc
Enlightened
:welcome:
I just want to say that if the LEDs require 13.5-15VDC, then you probably will not get any light if you feed it 12V. Your supply voltage should equal your forward voltage. Try a different LED or a different driver.
Forward voltage is the voltage required for the LED to draw the recommended amount of current. The LED needs to draw the proper amount of current to produce the advertised amount of light output. As you feed it voltage less than its forward voltage, then the current drawn will decrease. Therefore, the light output will be less than desired. If you feed it voltage more voltage than the forward voltage, then its possible that the LED can draw so much current that it can be damaged by heat or possibly instantly destroyed. Just remember that small changes in voltage can result in a huge increase or decrease in current draw. LEDs act much differently than your typical filament light bulb. (BTW, light bulbs can tolerate large changes in voltage input which results in smaller changes in current drawn).
For example, a common, and very generic, 1W LED (which is not much different than your 20W emitter) will usually draw the proper amount of current (350mA or 0.35A) when the forward voltage of about 3.2V is provided. This voltage varies by LED model, manufacturer, and even batch of LEDs. So, 0.35 X 3.2V is 1.12W. If you provide this 1W emitter with 3.4V, then the current drawn may increase to 700mA. 0.7A X 3.4V = 2.38W. This LED will require more heatsinking and may be pushing the current carrying capacity of the wiring within the LED package. Lets say you accidentally feed the emitter 4.0V, then the LED could draw over 1.5A of current! Most lower quality LEDs will be unable to transfer the heat away quick enough, and for some, the internal wiring may fuse open resulting in a total failure. On the other hand, feeding the LED with only 3.0V may result in the LED drawing only 50mA (0.05A) or less current. The LED will appear to be very dim.
It appears that your 20W LED has 18 "1W" LED dies mounted on a copper or aluminum slug. I am assuming that if the forward voltage is 13.5-15V, then the individual dies are internally wired in series-parallel. That means so many sets of LED are wired in series, then each set is wired in parallel. I cannot determine what is in series and what is in parallel, but if you can find the documentation for that LED, you can find its true forward voltage and required current draw (ebay sellers sometimes post very general electrical specifications).
There may be a Forward Voltage vs. Forward Current" chart for your LED if you can find documentation for it. The relationship is a unique curved line that allows you to predict how the LED will act for any voltage or current provided. This curve will shift around as the LED heats up from normal use, affecting its forward voltage. However, once you know how the LED reacts, you can deliver X.XX amount of current and expect a certain range of forward voltage (and vice verse).
LED emitters are very sensitive to voltage changes, so that is why it is best to design the circuit to use a current-regulated or constant-current LED driver. A current regulating LED driver will safely vary the voltage to the LED (nearly instantly) to provide the LED with a pre-programmed current level. If you find such a LED driver, then you still have to make sure that the driver is able to output enough of a max voltage that is equal to somewhat higher than the forward voltage of the LED. You also need to make sure that the voltage of the power source fits within the required range of the driver (no problem with line voltage AC input drivers). The driver you linked appears to be a constant voltage driver, with the capability of being able to deliver 5.0A if the load draws it. The driver is unable to control the current to the LED.
So, stick around for a little bit and we can help out. I would hold off with bidding until you are sure they two parts are truly compatible with each other (LED + driver). There are a bunch of friendly and helpful members here on the CPF. :thumbsup:
Cheer,
-Tony
I just want to say that if the LEDs require 13.5-15VDC, then you probably will not get any light if you feed it 12V. Your supply voltage should equal your forward voltage. Try a different LED or a different driver.
Forward voltage is the voltage required for the LED to draw the recommended amount of current. The LED needs to draw the proper amount of current to produce the advertised amount of light output. As you feed it voltage less than its forward voltage, then the current drawn will decrease. Therefore, the light output will be less than desired. If you feed it voltage more voltage than the forward voltage, then its possible that the LED can draw so much current that it can be damaged by heat or possibly instantly destroyed. Just remember that small changes in voltage can result in a huge increase or decrease in current draw. LEDs act much differently than your typical filament light bulb. (BTW, light bulbs can tolerate large changes in voltage input which results in smaller changes in current drawn).
For example, a common, and very generic, 1W LED (which is not much different than your 20W emitter) will usually draw the proper amount of current (350mA or 0.35A) when the forward voltage of about 3.2V is provided. This voltage varies by LED model, manufacturer, and even batch of LEDs. So, 0.35 X 3.2V is 1.12W. If you provide this 1W emitter with 3.4V, then the current drawn may increase to 700mA. 0.7A X 3.4V = 2.38W. This LED will require more heatsinking and may be pushing the current carrying capacity of the wiring within the LED package. Lets say you accidentally feed the emitter 4.0V, then the LED could draw over 1.5A of current! Most lower quality LEDs will be unable to transfer the heat away quick enough, and for some, the internal wiring may fuse open resulting in a total failure. On the other hand, feeding the LED with only 3.0V may result in the LED drawing only 50mA (0.05A) or less current. The LED will appear to be very dim.
It appears that your 20W LED has 18 "1W" LED dies mounted on a copper or aluminum slug. I am assuming that if the forward voltage is 13.5-15V, then the individual dies are internally wired in series-parallel. That means so many sets of LED are wired in series, then each set is wired in parallel. I cannot determine what is in series and what is in parallel, but if you can find the documentation for that LED, you can find its true forward voltage and required current draw (ebay sellers sometimes post very general electrical specifications).
There may be a Forward Voltage vs. Forward Current" chart for your LED if you can find documentation for it. The relationship is a unique curved line that allows you to predict how the LED will act for any voltage or current provided. This curve will shift around as the LED heats up from normal use, affecting its forward voltage. However, once you know how the LED reacts, you can deliver X.XX amount of current and expect a certain range of forward voltage (and vice verse).
LED emitters are very sensitive to voltage changes, so that is why it is best to design the circuit to use a current-regulated or constant-current LED driver. A current regulating LED driver will safely vary the voltage to the LED (nearly instantly) to provide the LED with a pre-programmed current level. If you find such a LED driver, then you still have to make sure that the driver is able to output enough of a max voltage that is equal to somewhat higher than the forward voltage of the LED. You also need to make sure that the voltage of the power source fits within the required range of the driver (no problem with line voltage AC input drivers). The driver you linked appears to be a constant voltage driver, with the capability of being able to deliver 5.0A if the load draws it. The driver is unable to control the current to the LED.
So, stick around for a little bit and we can help out. I would hold off with bidding until you are sure they two parts are truly compatible with each other (LED + driver). There are a bunch of friendly and helpful members here on the CPF. :thumbsup:
Cheer,
-Tony
Gryloc
Enlightened
I hope I didn't scare away stinggray :duck: Come back and learn and be merry!
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