Question About Load-Balancing Paralleled PSUs

Thread Starter

JazzMac251

Joined Apr 24, 2019
25
I'm trying to add some load balancing to three 5v 100watt PSUs run in parallel. From what I understand, I need to put some resistors in line with each + lead going out to the load. All the examples I'm running into on the internet of people demonstrating how to do this use a fixed load, but my load varies quite a bit. Does this change the circuit at all?

Thanks!
 

Thread Starter

JazzMac251

Joined Apr 24, 2019
25
How accurately can you match the PSU output voltages?
How much voltage can you afford to lose across the series resistors?
I've gotten each PSU to output 5.10v. They are, from what I can tell, pretty consistently within .01v of each other (now that I have them properly adjusted).

I'm running six 5v LED strips at 8.6A each, roughly 50A spread across each of the three 20A PSUs. Of course, 50A is only when they're all on at maximum brightness, which is hardly ever. It could be less than 1A when only a few are on at a time.

I could push the voltage up to 5.5v to spare a drop of about 1/2v, but the manufacturer claims they need 5v to function and die at 6v.
 

AlbertHall

Joined Jun 4, 2014
10,522
If you are driving six strips from 3 power supplies then the obvious solution is to run two strips from each supply then you don't need to worry about what happens when you parallel them.
 

Thread Starter

JazzMac251

Joined Apr 24, 2019
25
If you are driving six strips from 3 power supplies then the obvious solution is to run two strips from each supply then you don't need to worry about what happens when you parallel them.
If it were only that simple! I have to run them all off the same controller, which creates wicked ground loops if all the PSUs don't have a common ground on the DC side.
 

AlbertHall

Joined Jun 4, 2014
10,522
Why are there wicked ground loops if the grounds are commoned when the load is spilt but not when they are parallel connected?
 
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