Power LOTS of LED strips

[whohat]

I'm using about 100m of LPD8806 LED strips for a sculpture this year. The sculpture will consist of 20x 5m strips. The strips run at 5v 10A max per strip. My current problem is deciding how to power it all (pun intended). I'll probably end up powering it off my generator since a 12v solar set up is prohibitively expensive, so I'll probably go with AC to DC switching power supplies. Since the installation will be on the playa in dusty and possibly rainy conditions, the power supplies need to be waterproof and fanless, however it's difficult to find large power supplies that are sealed (I assume because of the heat they put out). So far, I've found this unit which will output 5v 12A and is IP67:
http://www.jameco.com/webapp/wcs/stores ... 2141190_-1
I'm not thrilled by this option because I'd need 20 of them (2A/meter=1 of these power supplies for every 5m strip, of which there are 20) and at $38 each, it is a very expensive solution. They also take 7 weeks to get in stock and I'd like to get this project rolling sooner than that. Any ideas about a different solution?
Some have suggested cheaper, higher current, non-waterproof power supplies in a weatherproof box with a hepa filter and some fans to maintain positive air pressure inside, but I'm hesitant to rely on a setup with so many moving parts. Does anyone have experience with a similar setup?
Many thanks to all in advance.

[oscillator]

For Aurora in 2011, we had about 100m of 12VDC 5050 RGB LEDS and used (5) 720W switching PSUs inside a dust-proof NEMA enclosure (with cable glands @ exit points). We used a large enough NEMA enclosure to afford air circulation, with plenty of spacing between PSUs. Things got warm, but no failures during the week. We used Anderson Power Pole connectors on the supply runs.

NEMA
http://www.automationdirect.com/adc/Sho ... Wall_Mount_

PSU
We ran a 12VDC system on the 5050 LED strips: http://www.jameco.com/webapp/wcs/stores ... _319944_-1

I would not recommend the PSU you have sourced (no fan). Factor in about -15% efficiency drop. Of course get one or two B/U PSUs.

Oh, and factor in the voltage drop for long power supply cable runs. We ran 4AWG from the NEMA box @ the tree base up to the controller pods. This is a helpful guide: http://en.wikipedia.org/wiki/American_wire_gauge

Good luck! Looking fwd to your project.

-Osc

[whohat]

Thanks for the detailed response. It seems like 5x 720w power supplies is overkill for 100m of these. Did you run them way under their rated limit to keep temperatures down?
I'm now looking at these power supplies:
http://www.jameco.com/webapp/wcs/stores ... CH%252BNAV
I figure they should each be able to run 10x 5m strips pretty easily, so with 2 running and 1 as a backup I should be set. The strips only pull 2A per meter when all LEDs are white and full brightness, which I don't plan to do too often, but it's nice to have the option in case I want to blind people.
I'm curious how these big power supplies do when enclosed without any ventilation. Even with an oversized enclosure, it seems like the heat would build up and trip the over temperature protection. Is there any enclosure like a NEMA box that is waterproof, dust proof and ventilated?

[gyre]

Large enough aluminum boxes can be used for a certain amount of cooling, especially if you can heatsink the units to the side of the box.

Old floodlight housings were built for this, and aluminum, not zinc.
The westinghouse 1000 watt are perfect with a separate ballast housing intended for heatsinking.
Newer holophane are aluminum.

[BBadger]

I would not seek out weatherproofed PSUs, but rather buy a metal box (like a cabinet), seal it up, mount your PSUs to the interior walls, and mount heatsinks on the outside of the cabinet where the PSUs are attached to draw away heat through conduction. For further heat dissipation, other heatsinks can be mounted inside and outside. In this manner the interior of your cabinet is isolated, but the heat can be conducted out. You can buy large heatsinks at sites like this.

[whohat]

Thanks everyone for the input.
In the end, I decided to use a bunch of smaller, waterproof power supplies. Each strip will be powered by its own 5v 12a power supply located near it's start. Each will have a long 120v ac power cord attached to a power strip in an enclosure (probably something ghetto, like a rubbermaid tote). I'm using these power supplies.

Here's why i decided against larger, fan-cooled units in an enclosure:
-Since my LED strips run at 5v, I can afford very little voltage drop. To run such a high amperage, I'd need to use a lot of really thick, expensive cable.
-I don't want to experiment with a non-vented enclosure and a power supply that produces a lot of heat. Plus, NEMA enclosures are pricey.
-The idea for heat-sinking through the enclosure wall is awesome, but I don't want to take apart the power supply and relocate the transistor and diode.

I'll post an update when it's set up. For now:

[gyre]

I don't know what you mean about expensive cables.
Thick enough yes.

You buy nema enclosures second hand.
Just has to be heat shedding.

A device without a flat sink area is possible, say with a large enough box, but a direct sinked area works best.
Should be one out there that doesn't require rebuilding.

Any metal shop could build you a box.
A large enough flat sheet is what's needed.
Heavy helps.
I had a friend that used to build amps on plywood sheets.
Open air did the cooling.

Did they work?
Ran concerts with them.


I found instructions for IC 5v regulators too.
Simple, if you're inclined.

[junglesmacks]

FWIW, you can afford some voltage drop on those strips without a problem. I run my WS2801s of off a 3.7v LiPo with zero problems and minimal brightness drop vs 5v.

[Clive]

Figured I would comment on this since I did a lot of work with these things.
[youtube][/youtube]
That is Jellypuss, which I built for Emphemerisle. It is coming to the burn this year and will be on the golden cafe dome.
it uses 40 RGB LED 5m strips, for a total of 200m. Power is provided by three 600 watt power supplies. The strips are bi-powered. meaning they get a power feed on each end of the strip, if you don't do that you are killing yourself.

Control and sequencing is all custom electronics. if anyone wants some, I can sell the boards. You have to populate them yourself though


Your best option sans generator is to use car batteries and charge them during the day with solar.

[BBadger]

To explain the dual-feeding: LED strips have inherent resistance due to the wiring. Given the length of the strips (5meter, ~15ft), this resistance can be significant if you apply power at only one end, as it will cause LEDs at the other end to appear dimmer due to less voltage available to the LEDs + current limiting resistors. Dual-feeding applies the voltage and ground at both ends of the strip in order to even out the voltage drop and brightness.

Still, even with dual-feeding the center regions of the strips may be dimmer than the edges, as the center is now furthest from the power-sources. A solution to this is to attach the power at only one end, and the ground at the other, so that the effective resistance at every LED along the strip is roughly the same.

[oscillator]

For 5 meter lengths, I do not agree with the above statement. There is no perceptual difference in a reasonably well-engineered single 5 meter +12VDC passive resistor LED strip when powered from one end.

Yes, there is a supply voltage drop over a greater length of wire (one much greater than 5 meters), that can be ameliorated, to some extent, by using heavier gauge wire.

Example: running supply lines on a light-gauge wire, down a row of LED strips, where the last strip is >50' out from the PSU. There will be some voltage drop @ that last LED strip, compared to the first (and that will affect the entire LED strip). Dual-feed power supplies would work well in that scenario, but will not make any difference on 16' (5 meters).

Don't believe me? See for yourself, I am running this exact scenario: Illumination Village 2:30 & Esplanade (playa side). Swing by, nights work best.

-Osc

[gyre]

How many years have you been with Illville?

[BBadger]

For 5 meter lengths, I do not agree with the above statement. There is no perceptual difference in a reasonably well-engineered single 5 meter +12VDC passive resistor LED strip when powered from one end.

Yes, there is a supply voltage drop over a greater length of wire (one much greater than 5 meters), that can be ameliorated, to some extent, by using heavier gauge wire.

Which is really the problem here: all this depends on the quality of the lights in question. For example, there are really cheap LED strands that use one LED for a whole parallel-connected array of LEDs--the very wrong practice of wiring LEDs. In the case of these 5m strands, the wire resistance really shouldn't make a noticeable difference, especially with the amperage needed for the strand. However, with suppliers cutting corners, and people wanting to buy stuff cheap, you never know; it seems like it made a noticeable difference in Clive's lights.

Another solution compared to dual feeding is to just up the voltage somewhat to compensate.