Want to build an outdoor LED flood light, help me or slap some sense into me.

[Wiggle]

I'd like to build an outdoor floodlight for my backyard. Sure I could buy something cheap and non-LED but thats no fun at all. Output around 5000lumens or more in a flood beam would be pretty good I think. I need to make a few choices:

Lots of Q5/R2 or a few P7/MC-E?

How should I do a power supply? I was just going to do a basic transformer, rectifier, filter cap that feeds that drivers, is this typical for this application?

What driver and LED configuration is smartest for this?

I realize working with line level power is dangerous but I've done it before several times and am comfortable with my ability to be safe.

Thanks for any advice.

 

[TigerhawkT3]

Might want to try threads like this one.

 

[LukeA]

Lots of Q5/R2 or a few P7/MC-E?

It's easier to effectively heatsink 4n XR-Es than n 4-die LEDs. There's lots more thermal pad surface area per unit of heat dissipated. Fewer W/cm^2 means better heatsinking.

IMO. YMMV.

Good luck and have fun!

 

[Al Combs]

I'd like to build an outdoor floodlight for my backyard. Sure I could buy something cheap and non-LED but thats no fun at all. Output around 5000lumens or more in a flood beam would be pretty good I think. I need to make a few choices:

Lots of Q5/R2 or a few P7/MC-E?

How should I do a power supply? I was just going to do a basic transformer, rectifier, filter cap that feeds that drivers, is this typical for this application?

What driver and LED configuration is smartest for this?

I realize working with line level power is dangerous but I've done it before several times and am comfortable with my ability to be safe.

Thanks for any advice.

Whatever setup you go with, wire them in series to keep the current the same for each LED in the string. LED's have a logarithmic current increase with a change in voltage. That makes having a constant current regulator pretty much madatory. Whatever type of LED you use, I think heat build up is going to be the real problem with your setup.

Wayne has a new driver called the Shark Buck that can put out 3 amps for P7's. A pair costs $54. He's out of stock at the moment. Here is a post about the Shark Buck in the Shoppe forum where he says you can "maybe" drive 4 with each driver. You would need at least 2 of them. If you got the newer D binned P7's, that would be 5,600 lumens for 7 of them, sweet.:)

The homemade power supply you describe should work as well as a battery. You could ask Wayne at the Shoppe forum mentioned above if RF or EMF noise might be a problem in that setup.

It would take about 23 Q5's to equal the output of 7 of the D binned P7's. Interesting thing is they're both about the same price, a little over $150. Well say 24 Q5's is a nice round number. R2's probably aren't worth the extra cost for their increase of output. 6 Q5's draw roughly 22.2 volts @ 1 amp. That's 4 Blue Sharks for $100. It says ≈32 volts max output, so maybe only 3 are needed. It's a boost regulator so an 18 volt transformer is about right for 6 LED's, or 24 volts for 8 LED's. A post by LED Zeppelin I didn't save mentioned if you don't need the headroom for dimming, the Sharks work better at higher voltage. They have higher efficiency so less heat build up. They still need to be potted though. I would run the whole idea by Wayne and ask him what he thinks.

The new CCHIPO boost regulator has a max output of 48 volts. You only need 2 of them @ $45 each to power a Q5 setup. These things have that heavy duty look about them and a 45 watt max output. The MaxFlex is another boost regulator very often compared to the Shark. It only has a 24 volt max output and at $32 is a little more expensive.

 

[Al Combs]

I forgot to mention and am not sure if you realize, the P7 if you go that way has the anode common to its rear surface. If you Arctic Silver them all to the same metal surface and wire them in series, you risk blowing the thing up. If you use P7's, use the stars. Same thing holds for the Q5's.

I didn't mention the Xitanium drivers at first because the only place I know to buy them is LED Supply. If you decide to use the Q5's, I think this is worth a look. OK it's only 700 ma and the 1,050 ma version is too expensive because it has a built-in dimmer you'll never use. But it's a only a 17% drop in output vs a 30% drop in heat. Also it has its own plug into the wall 120 volt transformer. It will save you the trouble and expense of making your own supply. The four you'll need is $112.

There is a 1,050 ma version of the Xitanium available without a dimmer that LED Supply doesn't sell. Perhaps you can track it down. The model number is LED-120A-0024V-10F.

 

[Wiggle]

It seems like the Shark buck looks pretty solid. And if I could drive 4 with each driver, may as well step up to 8-P7s for a little extra output. But looking at LukeA's post, do you think it will be difficult to manage the heat of 8 P7s running? I think I've got a 24V transformer floating around, which may actually be a little higher than I can get away with since once I rectify and filter that it'll be sitting at around 30V which is above the input max of 25

 

[Al Combs]

He's definitely right about the extra heat of a P7 in a given surface area. How about an all copper CPU heat sink? I think you're going to need forced air with a few muffin fans if you use P7's or Q5's.

To get away from a metal box that traps heat, it might help if you mount the regulators remotely indoors and just run the wires to your LED frame/heatsink. How about a 4" aluminum hollow pipe a foot long. Something that large should have no trouble dissipating 80 watts of heat. After you Arctic Silver epoxy a few P7 stars onto it, some silicon glue from a caulk gun on the solder joints should help make it weather proof. The LED dies are sensitive to moisture, but P7's are encapsulated in silicon. I'm not sure if you can leave an LED exposed to the elements like that or not.:shrug:

As far as a 24 volt transformer being just below the Shark Buck's max input threshold, you could use inductors for filtering instead of caps. The extra expense would be offset by the transformers you don't need to buy. Otherwise, get a lower voltage transformer. Don't forget to send us some pictures when you finish.

Good luck:twothumbs

 

[Data]

120V LEDs