Comment by MayeulC | Hacker News Reader

Comment by MayeulC | Hacker News Reader

I am most interested in that DC power supply. I bought a similar one recently (rgeek brand on aliexpress), but haven't yet dared to connect it yet.

I'm wondering what:

- the failure mode is if it can't provide enough current.

- How to properly test it under a fake load

- If these tiny power cables can really handle 150 W (this is 12 A at 12V). I don't have such a powerful 12V PSU, so I am thinking about adding capacitors to handle transients.

I imagine that it is really built to handle transient peaks to 150 W, with a more reasonable baseline.

Anyway, if anyone knows a good knowledge source for these PSU, I'd be interested.

My initial motication for going with these was:

- hopefully increase my PSU efficiency

- less cable clutter

- hopefully power it from a small DC UPS (there are plenty of "router" UPS sold on the market, though the power rating is a bit low, 18-36 W usually).

I have a RK3588 SBC with 5 HDDs and with a good ATX power source it draws about 24-26W from the wall socket. I tried replacing that with a 5A 12V DC power brick and the power usage increased to 28-30W.

Measurements are not accurate, but comparable. I used a Tasmota smart plug - the same one in both cases.

Thanks for the data point, and the vote of confidence. I do not have the best setup to measure power draw (I just broke my dedicated smart plug), but it it may also increase power draw in my case (20 to 30 W, ERYING M-ITX 12500H + 2 nvme SSDs). Your numbers are impressive for 5 HDDs, are they 3.5"?

Anyway, it may be a transient that I am measuring, as the PC turns off during the boot sequence, after the CPU fan starts revving up. My 5A PSU may not be enough, I'll try limiting the TDP and the power brick.

3x 3.5" and 2x 2.5"

Some power bricks are not up to the specs written on them. Get one of those USB power testers that have a barrel plug too. They're very informative in cases like these.

The parts linked on the post are performing well. If you size them well, the main issue you can run into is inrush current when powering up. You may need a soft start circuit. I know I'm at the limit and may need to add a soft start if I add more fans.

Thanks for the feedback! A triggered power-on seauence for drives and fans makes sense, though I feel like this could also be solved by putting a couple of large capacitors on the 12V power rail (those need to charge as well, obviously, which might be an issue on startup).

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