Homade led outdoor floodlight conversion

I had a 2 year old flood light (high pressure sodium light) that recently started to act up quite a bit. I decided to convert it to led.
here it is with the guts removed and the led driver in there.

7x cree xpg r5 cool white drivin at 700mA, i ended up adding another aluminum plate to help with the heat.

all together with optics installed, center ones are 65 degree (3 of them) and the outer ones are 40 degree optics (4 total).

all mounted and lit up

pictures of the back yard with it on. camera on phone can only do so much, better in person.

Great job, it looks like it really performs well. Does the aluminum plate get warm? I always find it tough to gauge how large it needs to be for sufficient cooling.

ya it gets pretty warm, 84 degree's F after 1hr, might end up putting a few computer heatsink to help with the cooling. it actually lights up the darker area's of the picture better then the picture shows.

shortstack said:

ya it gets pretty warm, 84 degree's F after 1hr, might end up putting a few computer heatsink to help with the cooling. it actually lights up the darker area's of the picture better then the picture shows.

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If you know your ambient temp and the watts dissipated [~20 W?] you can figure your thermal resistance in degrees C per W, housing to ambient.

Since noise is not an issue you could put a very small 'muffin fan' in the housing to assist in convection cooling.

You need more contact area between the light housing and the aluminum plate.

The other option is a small fan to move the air around a bit.

Great light.

sorry to bring up an old thread, but how does this compare to the high pressure sodium light. The reason i'm asking is because i'm debating on buying a 250 metal halide bulb, or making my own LED light

HPS has a CRI of 20, whereas the LED is around 70. Also you'll be saving on energy.

Uh, not really. HPS has terrible color rendering but it's more efficient than LED and certainly cheaper.

To match the out-put of a 250watt HPS you'd need a lot more wattage of LED's, which would almost require a commercial grade high bay LED fixture or something able to replace a municipal street light.

A 250watt standard daylight halide will still throw over 20,000 lumens. Most of the residential daylight class halide fixtures get trounced by XP-Gs in terms of efficiency, but the net lumen total is a different matter. It would take about 60 XP-Gs to match the out-put $10.00 250watt 4100k halide bulb.

mds82 said:

sorry to bring up an old thread, but how does this compare to the high pressure sodium light. The reason i'm asking is because i'm debating on buying a 250 metal halide bulb, or making my own LED light

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A 250w bulb is driven by a 300w ballast for that 20000lm single source light 20CRI light. And, either the bulb or ballast is pretty cheap to replace. You also won't need a 20lb aluminum heatsink.

If you want to use LED, you'll have to source LARGE LEDs, like what Citizen, Bridgelux, Edison, Sharp, LedEngin, Luminus, Epistar ... offer, and you'll need a heatsink/fan combo that can keep that 200w-250w of LEDs cool. And, efficiency improves with under driving the LED. So, you probably will need to get 3-5 of those large LEDs to 'compete'. You'll also have to build or source a suitable LED driver(s) for the build.

To daisy chain 100 XML/XPG/Rebels/P4's... to achieve that efficiency is a bit expensive and maybe silly. But, it is doable. I've seen LED street lights running numerous(50-150) 1w, 2w, or 3w, usually generic/discount brandLED's. So, that 100lm/w light isn't impossible, just very expensive when talking about 20000-25000lm output.

I prefer LED simply because I feel safe running it off DC and batteries.
If I were forced to use AC, and at those 20000lm+, I'd probably get HPS/Halide/induction....

Good points.

Thie biggest advantages with LED are obviously durability, ease of driving with both low voltage DC sources and high voltage AC sources, and most importantly directionality. If you want to spot light a specific portion of your yard and only need a few thousand lumens of white light that will turn on instantly in any weather and use only a trickle of energy LED is likely the best option. If you want to flood your entire yard with as much light as possible on a regular schedule metal halide or induction is going to be a lot cheaper.

A couple of gas stations in my area recently converted to high bay LEDs over their pumping stations, and they look really, really good. By contrast some stations down the street are still using metal halide, and the contrast of the two light sources and their particular advantages/disadvantages is striking. When I get a chance I'll snap a couple pics because it's worth talking about.