DIY High Power LED Retrofit

[deepdvnarq]

Wouldn't the 3rd fan be getting 24v with this configuration?

i wrote it backwards. if you wire two fans in parallel you still get 12v. then if you wire that pair with with the other fan in series, you raise it to 24v to match the power supply. thanks for catching that and sorry for the confusion.

 

i just read the rest of the post. you guys are on it. i apologize again.

[evilc66]

So, evil, is there a way to get three fans hooked up to a single 24v PS to run at their intended current & 12v each?

 

You can use a linear voltage regulator to drop the voltage, but it generates a lot of heat. You could screw the tab down to the main heatsink to cool it (electrically isolated of course).

[deepdvnarq]

You can use a linear voltage regulator to drop the voltage, but it generates a lot of heat. You could screw the tab down to the main heatsink to cool it (electrically isolated of course).

 

sooo.. at this point would it be easier to just get a cheap 12 v wall wart for $4.00 (just for the fans) and put the LEDs and the fans together on a timer or just add a fourth fan? i guess in regards to the fans are best in pairs if you want to use the same power supply. i now see where i went wrong. with a fourth, the two pairs can be connected in parralel and then the two pairs wired together in series would result in the disired voltage.

[tyty22]

wow i just finished reading this and i am amazed at first i thought an led setup would be impossible for me with very little expierence with this kind of stuff. but you made it seem so clear and simple.

 

i think i may build a setup for my 5.5 gallon tank in the near future. and after that a setup for my 20 long.

 

i have a couple quick questions.

1.) How do you know, how many leds to use inorder to achieve the equvilent wattage of metal halide or any other light

2.) The mA of the buckpuck determines the intensity of the light. right??

So would leds powered by 1000mA buckpuck be brighter then leds powered by 700mA buckpuck?

 

But when powering Royal Blue leds would it really be needed to power them with 1000mA, since they are blue and over powering them would just make them whiter?

 

EDIT one more question

 

do the leds you used come with predrilled mounting holes? or did you have to make your own

 

 

sorry so side track you guys.

 

im not sure how to wire the fans together but i thought of a way to only need one fan but get air flow through all the fins in the heatsink. have one fan pulling air through a flat funnel or like a triangle.

 

like this E> "E" being the heat sinks fins and ">" being a triangle with a single fan (or more) at the end pulling air out.

[evilc66]

The number of LEDs changes with the desired lighting intensity. It all about the spacing. You can use less LEDs for a 70W equivalent setup than you would for a 250W equivalent setup.

 

The number of LEDs doesn't greatly change the equivalent power levels. Adding optics and changing input current will get the desired results. The number of LEDs is mainly there for coverage. The overlap from each LED will increase the PAR levels, with more overlap getting more increase. Still won't match the increase of adding a lens or reflector.

 

Driving at 1000mA will give an increase over 700mA. The 30% increase in power won't give a 30% increase in light output. Running the royals at 1000mA will not make them whiter. Just brighter blue.

 

The heatsink will have to be tapped by you.

 

Best way to set up the fan over the heatsink is to have as large a fan as possible blowing directly onto the heatsink.

[mdavis203]

I'm thinking that maybe the simplest solution to the wiring issue would be to add a fourth fan. This would split the output of the power supply into four legs, two for LED's and two more with two fans in series on each.

 

Would this possibly cause a problem with current? I haven't even looked at power supplies and am not sure how much current a standard 24V power supply puts out or how much current a fan requires.

[evilc66]

Fans don't consume a lot of power. You can get power supplies with more than enough current.

 

Honestly, the easiest way to get the fans running is just to run a seperate 12v power supply. That way you can run as many fans as you want instead of running series-parallel setups.

[Waterproof]

Honestly, the easiest way to get the fans running is just to run a seperate 12v power supply. That way you can run as many fans as you want instead of running series-parallel setups.

+1. Either that or use fans in multiples of 2.

[tyty22]

thanks evilc66. i think i understand now.

 

although i don't think i was too clear aout my last question. i wanted to know wether or not the LED itself has a hole for a mounting screw.

[Waterproof]

i have a couple quick questions.

1.) How do you know, how many leds to use inorder to achieve the equvilent wattage of metal halide or any other light

2.) The mA of the buckpuck determines the intensity of the light. right??

So would leds powered by 1000mA buckpuck be brighter then leds powered by 700mA buckpuck?

 

do the leds you used come with predrilled mounting holes? or did you have to make your own

 

Getting uniform coverage, at least visually, will determine the # of LEDs you need. On an 8-gal, you won't need optics. I think 8-9 LEDs would do the trick for you. See my 9 LED layout a few posts back. Going with an 11-12 LED layout, wouldn't add much additional cost.

 

Go with the 1000mA buckpucks. I initially used 700mA and then went back later and bought a 1000mA as a replacement. Unless you're trying to work with an existing power supply, just get the 1000mA. You can use the potentiometers to turn the light down if need be. According to the Cree XR-E data sheet, there is about a 30% increase in luminous flux (175 vs 225). I noticed a difference between the 700mA and 1000mA buckpucks.

 

Yes, the LEDs are mounted on star boards that have notches for the screws.

[mdavis203]

Honestly, the easiest way to get the fans running is just to run a seperate 12v power supply. That way you can run as many fans as you want instead of running series-parallel setups.

 

I totally agree. However, the reason I'm leaning away from this option is that this introduces failure scenarios where you lose your fans while the lights are still on (e.g. power supply failing, stupid cat knocking it out of the outlet, someone inadvertantly unplugging it) leading to an overheating of the tank. I'd like to keep the possibility of that happening to a minimum.

 

I'm leaning toward the four-fan solution, since it appears that the BC14 hood can be adapted for the two extra fans. The only negative I can see here is the potential for increased evaporation, although maybe that's unfounded. I'd like to get by with not having an ATO, since my wife's already pissed that the BC14 cabinet doesn't match the rest of the living room furntiture, so I'd like to keep the footprint of my system small.

[tyty22]

thanks waterproof i have a better idea of what im looking at doing now.

also the close up picture helped explain how you attach them. im assuming you mount the LEDS right against the heatsink for the best heat transfer. right?

[mdavis203]

thanks waterproof i have a better idea of what im looking at doing now.

also the close up picture helped explain how you attach them. im assuming you mount the LEDS right against the heatsink for the best heat transfer. right?

Yes, but with a thin layer of thermal paste between the LED and heat sink. Readily available wherever you get PC parts. Arctic Silver is one of the best in the market, but it's pretty expensive and may be overkill for this application. But, if you have the coin... Either way, some sort of themal paste is a must.

[crs2k]

Waterproof,

 

Do you happen to have a picture of the back side of the heatsink with the LED's mounted and wired? I'm curious to see how you ran the wire.

 

Thanks!

[tyty22]

ok sounds easy enough

 

i have a couple more questions

 

1.) whats the difference between the Buckpuck with external dimming and the Buckpuck external dimming with potentiometer?

 

2.) the buck puck says it can run up to 6-3w LEDS but the Cree XR-E Leds run at 3.7w(but average at3.5w) at 1000mA does this mean the buckpuck can only run 5LEDs?

[Waterproof]

Do you happen to have a picture of the back side of the heatsink with the LED's mounted and wired? I'm curious to see how you ran the wire.

Here's the best I have. You'll get the idea. I ran the wires within the fins. When needed, I wrapped the wire around the ends of the heatsink to move to the next fin that I need to run along. I kept the short ends of the heatsink clear so I could attach the brackets.

 

ok sounds easy enough

 

i have a couple more questions

 

1.) whats the difference between the Buckpuck with external dimming and the Buckpuck external dimming with potentiometer?

 

2.) the buck puck says it can run up to 6-3w LEDS but the Cree XR-E Leds run at 3.7w(but average at3.5w) at 1000mA does this mean the buckpuck can only run 5LEDs?

 

1) The "external dimming w/ potentiometer" comes with a little dial that allows you to dim the LEDs. The "external dimming" model has the wires to allow for the insertion of a potentiometer. I recommend the ones that already come with the potentiometers. Otherwise, you'd have to go buy them, which would cost you the same amount of money in the end.

 

2) I asked evilc66 the same thing before and he said the buckpuck can run 6 of the LEDs. It's not limited to 6 x 3w = 18w. In other words, the buckpucks can run 6 LEDs each.

[Waterproof]

However, the reason I'm leaning away from this option is that this introduces failure scenarios where you lose your fans while the lights are still on (e.g. power supply failing, stupid cat knocking it out of the outlet, someone inadvertantly unplugging it) leading to an overheating of the tank. I'd like to keep the possibility of that happening to a minimum.

 

The only negative I can see here is the potential for increased evaporation, although maybe that's unfounded.

 

LEDs do not emit heat the same way PC or HM bulbs do. They emit their heat to the rear, away from the LED. This is then transferred to the heatsink. I noticed a decrease in tank temp when I switched to the LEDs. If the 12v PS failed, I doubt you'd overheat the tank. I'd be more concerned about the plastic hood getting hot. I'm not sure what temp the plastic could get before you had to worry about melting or fire. I think the heat would naturally dissipate through the hood vents fast enough that thehood temp wouldn't reach a danderous temp. This is just speculation.

 

If you do a setup like mine, the fans are housed within the acrylic splashguard. So, adding more fans will not result in more evaporation. Actually, I've noticed less evap now that the LEDs are in place. I also do not get the moisture buildup on the splashguard that I used to get with the PCs. This is because the LEDs do not emit heat out the front, like I mentioned above.

[mdavis203]

I was hoping that was the answer. I think I'll go with a fourth fan. You don't happen to have a link to the fan you purchased or a recommended power supply, do you?

[Waterproof]

I was hoping that was the answer. I think I'll go with a fourth fan. You don't happen to have a link to the fan you purchased or a recommended power supply, do you?

 

I used 60mm Silenx fans. I switched out the stock biocube fans a long time ago to cut down on noise. The in/out fans needed to be trimmed down to fit, but the additional fan (for the heatsink) fits as-is. Any 50-60mm fan will work. I paid more for Silenx to keep it quiet. Newegg.com has decent prices on fans.

 

You can find a 24v PS on ebay for pretty cheap. Just do a search. LEDsupply used to have them, but now they only have an expensive 4a model.

[mdavis203]

Would two of those heatsink fans fit without too much trouble, instead of just one?

[Waterproof]

Would two of those heatsink fans fit without too much trouble, instead of just one?

yeah, there should be plenty of room. Here's a pic with just one installed.

[deepdvnarq]

I was hoping that was the answer. I think I'll go with a fourth fan. You don't happen to have a link to the fan you purchased or a recommended power supply, do you?

you can get this power supply which would be more than plenty:

24v PS 6.5amps

if you indeed wanted to get a separate PS for fans:

http://www.mpja.com/prodinfo.asp?number=17566+PD

[mdavis203]

Great! Thanks again for all your help, guys.

 

I ordered two of these fans last night. I went with the lower cfm SilenX, since I was getting two.

[Waterproof]

I've recieved some questions about layout and spacing so I threw together these templates. The first three are for 9, 11, and 12 LED configurations. If you print the file at 72dpi, you'll end up with an 8.5"x5" image. This may be tricky if you don't know what you're doing, so I made three other templates that are formatted to be printed as 8"x10" images. You can specify the print size in most programs. In windows, right click the image and select "print". This will open the Photo Printing Wizard. Move through the wizard and select the "8x10 in. cutout print" option. Remember, this layout is based on the 8.5"x5" heatsink that I used.

 

The circles do not represent the actual size of the starboard as this can vary. Rather, it allows you to center your LEDs so that you get a uniform layout. Then, using a single LED as a go-by, I recommend you do the sharpie marker approach that I explained in my original post.

 

To scale images:

 

8"x10" formatted images:

 

PS - I've added some combined layouts to post #101. If you wanted to be prepared to shift your LEDs around (i.e. switch between a 9, 11, and 12 LED configuration), you could drill & tap all the required holes before you started mounting the LEDs.

[mdavis203]

That'll be a HUGE help, WP. Question about your 12-LED layout, how would you do the white/blue placement to get a good blending. When I was ordering parts, I initially started planning on a 12-LED setup, to get the most I could out of the two drivers. However, I couldn't come up with a good layout, so ended up ordering and planning for the 11-LED system, like the one in your original post. I was worried that a 12-LED layout like the one above would end up with the light looking uneven.

 

Again, thanks for all of your work!