# Thread: LEDengin 5w and 10W info and wiring guide....for noobs

1. Originally Posted by FenderBender
You got it!

Except, you need to remember that the second equation for calculating power is from the voltage 'drop'. Meaning that if your LED is 6v (series wired red for example) and your source is 7.4, then your drop is 1.4v x I (current) 1.5 = 2.1 So you'd use a 2W resistor.

For a parallel set up, like for two Green dice, at say 3.8V it would be 7.4-3.8 =3.6 X 1.5 = 5.4 So you'd use a 5W resistor. Or, if you're using the SMD 2512 resistors you can 'stack' them. It's just more math

Thanks guys! This is for you. I will continue to add to it, as I know it's missing some clarification and more/better pics.
Excellent! So power source minus forward voltage. I have been trying to understand that equation for days! This is truly a wonderful day!

2. what does I stand for in the equation?
also how do you get the data sheets for the LED's? the link sends me to ledengine's site but i cant get the data sheet off their site

Edit: got the data sheet working. it was a problem with my computer.
so then i'm guessing you take the voltage it's asking for all 4 dies and divide by 4 to get the individual die power rating?

how far is it safe to overdrive these?

3. The data sheets will list the minimum and maximum vf for each color die based on a binning system. Though....LEDengin doesn't mark their LEDs so you won't know which bin anyway. Most of them can be overdriven to 1.5A ok.

4. [QUOTEOnce all your pads are tinned, start adding your trimmings (if you are doing series pairs of LEDs) like the pic above. I solder one end of the trimming to the first pad (Die1-) and then bend it to fit on Die2+. Solder it down and trim any excess. Do this to the other pair and then add your main lead wires.[/QUOTE]

Im confused why a - and + are being bridged, sorry for the noob question. also I understand the full powah diagram, but am still confused on how to set up FOC, this is very very very new to me but am willing to learn. thank you for your post and info im learning alot.

5. Thanks for the tut. It has avoided me destroying what you call "valuable things"

6. Originally Posted by Xanatos1986
Once all your pads are tinned, start adding your trimmings (if you are doing series pairs of LEDs) like the pic above. I solder one end of the trimming to the first pad (Die1-) and then bend it to fit on Die2+. Solder it down and trim any excess. Do this to the other pair and then add your main lead wires.
Im confused why a - and + are being bridged, sorry for the noob question. also I understand the full powah diagram, but am still confused on how to set up FOC, this is very very very new to me but am willing to learn. thank you for your post and info im learning alot.
That's what Fenderbender means by a series connection. That connects the positive from the first led to the source, that led's negative to the next one's positive, then the second led's negative back to the source voltage's negative. This essentially creates one led from the two. Current remains constant between the two, but will require double the forward voltage.

7. sweet i get it now so thats why its ok to run it at max amp on the pc/cf.

8. To help clarify what series and parallel connected leds configurations are. here is a diagram of a series /parallel setup.

Here is a diagram of the circuit.

Things to keep in mind.

Two of the lower voltage needy leds (red, amber), in series (in line) need about 5.5 volts to be driven properly (1 amp). No problem for a 7.4v pack.

Two of the higher voltage needy leds (blue, green, white) in series (in line) need about 7.4 volts to be driven properly (1 amp). Problem for 7.4v pack. The problem is that pack voltage will drop below 7.4v before the pack is half drained.

Also the battery pack must be able to provide enough current at the led voltage. In the setup above that would be 2 amps at 7.4v plus .5 amp for sound and accent leds. This means that a single battery of the 7.4v pack must be able to safely supply 3 amps of current.

9. i have a question ,i want to run two die's of a 10w blue from a pc board no foc and am not sure weather its best to wire them in series or parallel? im using a 7.4 v 14500 pack as im limited for space, ideally i wanted to use 18650s but no way will they fit

10. Its tough because the vf of two blue or green dice are usually right at the threshold of a 7.4v pack. I have had sometimes where it worked great, and other times where it failed miserably and I had to re-wire them in parallel. I try to avoid the // wiring on PC as it only puts out 1.5A (750ma each die). That isn't horrible, but its not optimal. Still, it would be pretty bright.

Try it in series first, if it doesn't look good, re-wire it for a parallel set-up. You can also, use the diagram above and wire the second pair for full power and get REALLY bright......but your runtime on a 14500 pack would suck......still.....mmmmmm

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