05-04-2018, 02:54 PM
(This post was last modified: 05-04-2018, 02:59 PM by hopkinskong.)
(05-03-2018, 04:51 PM)chrisf Wrote:(04-29-2018, 11:35 AM)hopkinskong Wrote: No, I didn't measure the power consumption. I was relying the current draw information printed on the hard disk label. It says how many Amps it will drawn from the +12V rail and +5V rail. for a 120W (12V 10A) power brick, minus 3A for RockPro64, there is 7A left for your hard drive and peripherals. Running 3-4 drives shouldn't be a problem. If not all of them will be running at full seek and spin, you may even add more hard drives.
Regarding the 5V rail, of course you can run multiple LM2596S-5.0 on multiple drives, just make sure you don't short out the 5V rails (GND of course need to be common). I would say powering 2 3.5' HDD per LM2596S-5.0 is pretty safe. Or you can always grab a better IC to provide higher current for your 5V rail.
Unless you can guarantee staggered spin up, not only when first powering up but also when the drives resume from sleep, you should allow at least 30W per 3.5" drive. Hard drives consume a lot more power than the numbers printed on them when spinning up the platters.
A quick google shows it's typical for a 3.5" 7200 rpm drive to consume 700mA on the 5V rail and peaks of 2.5A on the 12V rail during spin up. The last thing you want to happen is for your PSU to go in to current limit protection and shut down.
I wouldn't run 4 drives on a 120W PSU without first testing how much the drives consume.
1. You can use hdparm to configure SSU
2. Peak current still depends on the drives. WD Green drives only peak at 1.75A according to the official datasheet. 1.5TB drivers only peak at 1.00A. (But who still uses 1.5TB drives for NAS nowadays
)3. Maybe you can put a high capacitance capacitor on the 12V rail per HDD?
http://web.archive.org/web/2015051022531...language=1
