New
#201
Thanks, Jack!
Ok, here are my calculations: a WD Black (the only HDD I will use inside a computer) draws up to 10.7 watts under full load. 10.7 divided by 12 = 0.892A, rounded up to 0.9A. Since at least one of the drives will be an SSD, which runs on 5v, only eight HDDs need to be included in the calculation. 8 x 0.9A = 7.2A. I used a voltage drop calculator online to calculate the voltage drop for #14AWG at 7.5A, 12v, and a run of 2' (this was an estimated length since I did the calculations before making the cable) and got the following results.
Voltage drop: 0.076
Voltage drop percentage: 0.63%
Voltage at the end: 11.924
I could have easily gotten away with #16 AWG with these results...
Voltage drop: 0.12
Voltage drop percentage: 1.00%
Voltage at the end: 11.88
...but, as I said, I already the #14 AWG on hand and hadn't had any problems with crimping pins on it before.
I wanted to keep the voltage drop as low a possible to avoid having a HDD drop out briefly while another one spins up. That's also the reason why the two hot swap bays will get their own cables (although both cables will feed from the same plug at the PSU; I'll have to do a splice and solder job on that cable to avoid problems with the pins); I've read reviews on the Antec EasySATA swap bay I'm using where people had problems with drives dropping out when a drive was inserted unless the bay had its own cable.
The only time all my HDDs will be under full load at the same time will be when booting up. Avoiding voltage drop as much as possible may help them to last longer since they would have to work harder to spin up if the voltage drops too much.
Granted, the figures I'm working with are very conservative but it's far easier to over-engineer now than to have to redo things later.
As far as making your cables goes, it took me over 12 hours to make this cable up; at that rate, you couldn't afford me.