Almost three years gone since question was asked, but I think my answer still could be actual for some people.
I also was curious about power consumption of modern 2.5" drives, but didn't found any good articles except this discussion and THG article about 500 Gb drives (mentioned in question). After some further googling I've found official specification of Seagate Barracuda 2.5" 3/4/5 Tb drives for spinning up/reading/writing/sleep modes.
Since all modern 2.5" HDDs are more or less common in their implementation we can use this specification as reference, but keeping in mind that other drives could have deviation up to 20% in comparison to this specification (like in question's table).
For archival purposes here is excerpt from the specification.
Typical power measurements are based on an average of drives tested, under nominal
conditions, at 25°C ambient temperature. These power measurements are done with
DIPM enabled.
• Spinup current is measured from the time of power-on to the time
that the drive spindle reaches operating speed.
• Read/Write current is measured with the heads on track, based on
three 64 sector read or write operations every 100 ms.
• The drive supports two idle modes: Active Idle mode and Low Power Idle
mode.
┌────────────────────────┬───────────────────────────┐
│ Power Dissipation │ 5TB, 4TB & 3TB models │
│ │ +5V input average (25° C) │
├────────────────────────┼───────────────────────────┤
│ Spinup (max) │ 1.2A (6W) │
├────────────────────────┼───────────────────────────┤
│ Write average │ 2.10W │
├────────────────────────┼───────────────────────────┤
│ Read average │ 1.90W │
├────────────────────────┼───────────────────────────┤
│ Idle, low power mode │ 0.85W │
├────────────────────────┼───────────────────────────┤
│ Standby/sleep │ 0.18W │
└────────────────────────┴───────────────────────────┘
Standby power is measured at steady state (after 200ms from transition)
P.S.: I'm not affiliated with Seagate company in any possible way.
If it's designed to be powered through just the USB port you should be fine. – pjc50 – 2017-01-25T15:14:19.100
I heard that using regular HDD connected to laptop's USB socket as external drive isn't very good for motherboard That is nonesense, as long as the laptop's USB socket can deliver the required power, it will work fine and is not bad for the motherboard. Whoever said this clearly has little understanding of this subject. – Bimpelrekkie – 2017-01-25T15:28:47.217
You can google for a picture of a similar spec hdd and the current ratings are usually printed on the label of the bare drive. – user3528438 – 2017-01-25T15:38:19.187
I googled for "wd 7200rpm 2.5" and it seems quite a few of them are at the 5V/0.55A level. So if you put one of those bare drives into a after market USB HDD case then you are indeed challenging the motherboard. – user3528438 – 2017-01-25T15:45:08.430
..as long as the laptop's USB socket can deliver the required power, it will work fine and is not bad for the motherboard. I understand that it should be in theory. So laptop brand manufacturers (say Dell) not strictly follow standards, or may not follow standards at all. – triwo – 2017-01-25T15:54:15.670
I've had 9 USB HDDs hanging of a single intel NUC board and it kept going, most motherboards are tougher than you think. Plus, they tend to have fuses and over-current disconnect circuitry nowadays anyway (but that's a relatively recent development). If you're still concerned, does your computer support fast charging of mobile phones? If yes, then it's been designed to handle a good 2A from at least one port (and if it's a USB3 port then by design it must be capable of 0.9A or 4.5W compared to the standard 2.5W) – None – 2017-01-25T22:33:36.287
But the most interesting part isn't average consumption but spikes, for spinning up or large writes or whatever. You wouldn't want the drive to suddenly shut down at those times. – Daniel B – 2017-01-26T17:39:45.413
so if I understood correctly a 5V2A hub should be able to power on average 4-5 2.5" laptop drives all running at the same time? – Mikey – 2018-01-04T11:44:39.933