Building Eight Port 5V 2A Power Distribution System

[Questnfool]

Hello all electronics wizards,

I hope I am posting in the right area and to the right group of gurus, please forgive me if not.

I have been scouring the internet trying to find the necessary information to build a power distribution board to which I can connect multiple Raspberry PI boxes. I know that the PIs each take 5V 2A power in, each with their own wall wart. Since I am looking at using many PIs, the number of wall warts starts to get silly the more I think about scaling up this project.

I intend to mount multiples (starting with at least 8) of these in a server rack and I would like to optimize their space utilization. I was thinking about gutting a 2U server chassis (which will hold a lot of PI) and modifying the ATX power supply to feed them. Unfortunately I have yet to find any schematics or discussions along that line.

The best I have found is to purchase a switching power supply, send that to a fused distribution board, and then feed the PIs from that. I am thinking about the the following.

Mean Well 90W 5V 18A Switching Power Supply
http://www.mouser.com/ProductDetail...3th5F8koMf/a2V0paI9dHcmOgjlHC0wq/%2bqAqhkdw==

Altronix 8 Output Power Distribution Board
http://www.zoro.com/altronix-power-...hopping_Feed&gclid=CLanuYyq5ccCFYSQHwodNZ0NXg​

I have the most rudimentary knowledge of electronics. I know about voltage, amperage, and resistance and that's about it. Ask me to figure out parallel circuits, and I'm out.

So here are my questions.

1) Is it possible to use a standard ATX power supply to do the task? I'm not sure the needed amperes are there on the 5V rail (assume 250W power supply).

2) Would it be possible to feed off the 12V rail and step-down it to 5V? And if I could use the 12V step-down and 5V feeds, any clue what the total available amperes would be, again assuming a 250W power supply.

2) Sans the ATX hack, will the power supply-to-distribution concept work? I want to ensure the health of the multiples of PIs that I am purchasing.

3) Could I scale up the power supply and parallel two or more boards if needed? I know I can buy up to a 120A supply (which I think would could be 59 PI). Would it be okay to feed one PI with a 5V 120A input through a 2A fuse? (Somehow that much pressure seems scary.)

4) Is there a better way to do this? I am happy to build something if it is better suited to the task, ideas, diagrams, and the like are all welcome.​

Thank you ahead of time for any valuable insight, feedback, or ideas you can provide.

~Questn

 

[Alec_t]

Welcome to EP!
This thread may answer some of your questions.

 

[Questnfool]

Thanks Alec_t!

After reading that thread and some additional electronics research I have done, I have the electronics answers for which I was looking.

1) Is it possible to use a standard ATX power supply to do the task? YES! Plus, I found a general amperage chart for power supplies here. This means I can use a power supply that was designed to be in the server case, vice having to hack a different one into it.

2) Would it be possible to feed off the 12V rail and step-down it to 5V? I found that I do not have to do this. However, it remains unanswered and it would be good to know.

2) Sans the ATX hack, will the power supply-to-distribution concept work? YES!

3) Could I scale up the power supply and parallel two or more boards if needed? YES!

4) Is there a better way to do this? Not answered yet. If you have any recommendations, please post. If I find a better way, I will let you all know.​

Again, thanks!

~Questn