# Not Clear on how many Power supplies I need

Discussion in 'Power Supplies' started by ezimnow, Jun 11, 2014.

1. ### ezimnowNew Elf

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Just want to be sure I have this configured right...I probably don't and I don't want to burn out my pixels if I made an error...

I have 12 WS2811 IP68 12v pixel (50 cnt)connected to a ECGP-12R. I string per bank

Power supplies are 2 12v 360W...

Math 0.3 watts per string *50 12v
3amps per string= 36A
= 432 Watts?

So I would hook up one 12V power supply per side on the Controller or just the one to power the 12 strings?

Thank you

2. ### dale82Senior Elf

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Hi there, Firstly welcome to ACL and secondly, You have plenty of power. A p12 is capable of running 170 pixels per output and you are using 50 per output as far as I can tell (attach a link to the lights so that we are sure). I use 2 PSU in total for my p12, 1 per bank. Also jump into chat as there is also lots of people that can talk you through any problems that you encounter.

3. ### AAHI love blinky lights :)Community Project Designer

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There's a slight mistake in your maths. You believed the Chinese specs on an Aliexpress page.
For the sake of working out your power requirements you can assume a working current of 60mA per pixel (55mA is probably closer to theoretical and 50mA is what is actually likely unless you have awesome power injection). The 60mA doesn't matter if it's at 5V or 12V as the pixels are constant current typically and the extra volts goes into heat. Using that you get 12V x 0.060A which gives 0.72W per pixel or 36W per string of 50 or a total wattage of 432W. With voltage losses (and the fact that the calculations were done at 60mA) you are likely to be well under 400W.
As far as pixels per output you are certainly under doing what the P12 is capable of. You can happily put 3 strings on an output or if you were using a P2 you could have all 600 pixels on the 1 output and leave 1 free.

4. OP

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