Will my PSU handle the load?

[Yodeling]

I just finished an upgrade on my LED fixture and it's now nearly perfect, but I'm thinking of adding a few more mini-clusters of RB/Violet into the mix. With the added LEDs, the power consumption would be about 341W at full power (currently it's about 282W) The PSU is 48V at 7.5 amps, so theoretically it should handle it but I'm wondering if I'd be pushing it too hard. Any thoughts?

 

[Gorgok]

Are you basing the LED wattage off volts and amps or just 'wattage' ratings? Also are you running the LEDs on a ramp cycle or just on/off? Finally, are you running the LEDs at full power or is something always dimmed for color blend?

If you are using real wattage, then you are pretty safe. More so if you run them on a ramp, because you will only hit the high loads for a short time, or if you don't ever run them that hard.

If you are basing the numbers are 'wattage' guidelines for LEDs you could be severely under or over estimating the power consumption, depending on the actual color and type of LED. Even worse if you run them full power for full duration...

I don't think a good PSU should fail running at 95% rated load for a good long while, but its a little excessive. An hour a day with the rest being light loads i don't think id even worry about it... A cheap PSU would probably start cooking though, and sooner than later let out the magic smoke from some part or another.

 

[Yodeling]

Thanks for the advice. This is a chinese PSU from ebay. My plan was to run everything at maximum for about 2 hours a day, the rest would be ramping up or down.

I used measured voltage from each driver and its amp rating and added them up. But you're totally right, the actual draw from the PSU has to be higher. I'll measure the volt/amps and go with that. Really good call, as I'm probably closer to maxing it out than I thought.

I think I'll just buy another PSU and distribute the load between them. This will give me some upgradability as well since I can't seem to keep my hands off it.

Thanks for your help!

 

[karimwassef]

As you approach the higher demands against the rating of a power supply, you need to look the thermal management requirements. Most engineers designing power would give a 20% buffer and only go into the 95% for short peaks (few minutes).

Without looking at the thermal rating or airflow requirements of the PS, it's hard to tell. If you can, run it with thermal probes and see if you need to add cooling for the PS.

 

[mcgyvr]

I never run a power supply at more than 80% of its rating continuously.
and even less for the Chinese crap..