Generic unbranded S-350W 5V supply testing

[AussiePhil]

Had a question in chat last night about testing of the generic 350w supplies.

I had one inside that was getting a fan replaced so finished off that work, wired up a pair of 14AWG cables, 600mm long to connect the supply to the electronic load.
I didn't have enough connectors to do a third pair.

This supply is an ebay/Ali special, it would have been cheap as possible at the time and would be at least 7 years old now.

General advice has been and remains the same... do NOT run these at 100%.

Photo proof that 50A wasn't and issue..... I did wind this up to 60A and never tripped any over current protection... the load only handles 60A though
Parameter
PSU supply set for 5.30v output



The eagle eyed may ask why the drop in voltage... the supply dropped 150mV at 60A, the rest of the drop was just on the 600mm of 14AWG that was also getting hot.



The two observer hot spots are circled in red below
The switching mosfets on the side really started to put out some heat ... and the wires actually got hot.




TLDR:
Observations:
Voltage sag on the supply itself was not an issue, 150mV max
It will handle 60A for a period, i only tested for a couple minutes and it smelt HOT
It will output 50A consistently but needs decent cooling, especially don't block the vents on the bottom, note the supply is elevated.
It will output 40A and below and not be hot but don't use in a sealed case.
14AWG even at only 2 feet,600mm gets hot dual runs from a supply to a controller should be dual wires even at 30A

This is constant load testing, you would never see this in real life for any length of time but obey the 80% load guideline and de-rate these to 50A and you should not seen issues.

Cheers
Phil

 

[i13]

Thanks AussiePhil for sharing this. In addition to this, I have measured that the power factor of power supplies like this (and the Mean Well LRS-350-5) seems to consistently be 0.5 which is not great. This thread has more info on the topic: https://auschristmaslighting.com/threads/6365/

 

[AAH]

Nice Phil
More test gear porn
I'd love to see some test info on those who mount multiple supplies in an enclosure and especially with the 3D printed mounts which I suspect mount directly over 1 of those hot spots.

 

[AussiePhil]

Nice Phil
More test gear porn
I'd love to see some test info on those who mount multiple supplies in an enclosure and especially with the 3D printed mounts which I suspect mount directly over 1 of those hot spots.

Hi Allan

Many thanks, loving the ability to actually test this stuff now.
I am thinking though that it is good to test the extremes and see that things won't blow up or overheat quickly, I need to be careful to balance that with normal usage in a light display.
The worst case testing as in 100% dump into an electronic load is simulating 100% white for the same period. I don't know of a display on the world that has 100% white for more than a few seconds at worst.

This would mean that whilst it is good to know the hotspots to allow for mounting once you drop down to average loading they seem to be a non issue.

In a closed case with multiple supplies though that will be a different story due to air flow or based on a lot of the photo's lack of air flow... the thermal camera should arrive in Jan so we can look at that more then.

After the original post that supply delivered 30A constant for another few hours and showed no heat stress.

I suspect that the failures get high level coverage and the reasons are not investigated, the story just becomes cheap is bad and meanwell is good... likely no debate on MW being good (real ones) but cheap isn't automatically bad. All my 350w units are cheap and cheerful and touch wood all still work, couple need fan replacements, I have two 48v units in the home theater setup that run 365x24 and have done so for 7 years straight.