Power requirements for Pixel Tree

[stormboy2340]

I'm trying to work out the best way to power my pixel tree.
It consists of 64 strands @ 80 pixels per strands for a total of 5120 pixels.
So using the 50mA per pixel standard I'm looking at 4Amps a strand and a total of 256Amps.
Pixels are 12v WS2811

I need some help and opinions on powering this.
I think I worked out I would need 16 300w power supplies just for my tree.

Any help would be greatly appreciated.

 

[Ellis]

64 strands? that's going to make it very wide at the top isn't it?

 

[stormboy2340]

Base is 1833mm dia
Top is 408mm dia
Strand length 4000mm
Height from base to top 4500mm

 

[Ellis]

yeah ok cool, so 2cm each string at the top approx.

Depends on what you are using for PSUs and pixels

Assuming you are using 12v nodes... (approx.)0.8w/node so 4096 watts at 100%

If using cheap power supplies running at 80% that would be 5100 watts approx. allowance.

That makes it 17 300w PSUs

That's the way I calculate it anyway but I am sure others will chime in.

 

[stormboy2340]

I've been thinking about reducing my tophat dis and having 2 "rings" 10mm apart and every second strand on the second ring
Doing this I could reduce my tophat to around 250 - 300 mm

 

[stormboy2340]

I thought I was missing something with my power calculation's, I've been looking at alot of other peoples setups and they don't seem to be using that may psu for their entire display

 

[Ellis]

I thought I was missing something with my power calculation's, I've been looking at alot of other peoples setups and they don't seem to be using that may psu for their entire display

If you mean the walk through videos, they more than likely don't show all the PSU's

 

[stormboy2340]

My viewing distance is around 10 - 15m that's why I've gone with a tighter 50mm pixel spacing, but I'm thinking its going to be very bright at that distance.

If I was to drop my intensity to 50% I could possibly half my power requirements or is that bad practice

 

[AAH]

Any particular reason for 12V pixels? They are a lot less efficient that 5V ones and with a mega tree is is exceptionally easy to handle power injection.
At 55mA per pixel which is the design spec for 2811 it's 281A at either 5V or 12V. For 5V this would mean a total power of just over 1400W at full white. For the exact same brightness with 12V it's 3372W which is more than you can get out of a standard power point but it's still within the 20A per power circuit. With even 1400W of leds in such a small space you're going to have to run at lower than 100% simply because of the incredible brightness.
With 5V power supplies you could get away with 4 if you pushed the friendship with them and with 12V you're going to want 10.

 

[Steve22537]

Have you thought about using 5v, only 5 power supplies. Injection is going to be easy, inject at the top.
50ma x 5120pixels = 256amps
256amps x 5volts = 1280watts
6 x 300watt power supplies = 1800 watts
1800watts at 70% usage would be = 1260watts
You could get away with 5 supplies.

Steve

 

[stormboy2340]

Thanks AAH, 5v seems to be the better way to go.

Do you always all for for 100% intensity with your power requirements even though in practice you'll be running a lower intensity

 

[stormboy2340]

Ok, so I'm going to make the switch to 5v pixels.
My next decision do I purchase several se-350-5 psu @ $51 ea or a single se-1500-5 @ $300.

What are the pros and cons of multiple smaller power supplies over a single larger one

 

[Steve22537]

The 1500w PS will take up less space, but multiple power supplies provide a bit of a safety net for redundancy. Cost is about the same.
Steve

 

[stormboy2340]

Am I right in saying that running a single larger power supply would make injection easier, only need to run a heavy twin core to the top and bottom with fused distribution at top and bottom

 

[scamper]

Am I right in saying that running a single larger power supply would make injection easier, only need to run a heavy twin core to the top and bottom with fused distribution at top and bottom

Not necessarily. it does depend on your setup.
You can run several power supplies and run several wires. I prefer several smaller (relatively speaking) wires than one massive wire. The large wires can be expensive, hard to work with and once again safety and redundancy. A loose terminal in a wire carrying 100 amps is going to cause a spark/fire easier than smaller lower current wires. The fuse you speak of is not going to do much as it is the size of a shunt and you are still going to get some big arcs before that sucker blows.