You’re absolutely right. TB2 does not deliver power over the adapter. [edit]
Don’t have the cables so can’t try it. I bought it for a network file share and it’s plenty fast for that…my hope was to boot from it as well since doing anything on it is slow interface wise. But I only rarely Screens 4 into it for remote management so I can live with the slow app opening, Finder window refresh etc…I only connect to it mon5ly or so anyway.
Slight correction. TB2 delivers power, but Apple’s TB3-TB2 adapter does not.
So if you have a bus-powered device with a TB2 (or TB1) interface, you can plug it in to an older Mac with a TB2 (or TB1) port. But you can not plug it into a modern (TB3) Mac via Apple’s adapter.
You should (I assume, but haven’t read proof yet) be able to work around this using a hub or dock that can supply the missing power. For example, a TB3 device connected to a powered (that is, which its own separate power supply) TB3 dock that is in turn connected to a TB2 Mac via an adapter. Or a powered TB2 dock connected (via an adapter) to a TB3 Mac, supplying power to a bus-powered TB2 drive.
Interesting! I had a number of TB2 macs and never discovered a bus-powered TB2 drive. Perhaps TB2 ports supplied enough power for some other type of non powered devices (card readers?)
I used a TB2 LaCie Little Big Disk which needed its own power brick, and I also had a Lacie Rugged which could be either TB2 or USB-C, but needed its own supplied power brick to use the TB2 connection.
I would have bought a bus-powered TB2 drive in a heartbeat (at least if it was SSD)!
That’s right. TB2 in principle offers up to 10 W on its bus and that would be enough to power a small SSD like the T7, but of course only if connected native to a TB2 port. Anything attached over a TB2-3 adapter is data only as per Apple spec. It’s a neat adapter because it’s bidirectional, but it only transfers signals, not power. So any TB3 device that gets its power exclusively over the bus, cannot connect to a Mac over a TB2 port. Same for USB-C devices since USB-C does not know about TB2 (unlike TB3 which knows about USB). Those have to connect to USB ports.
According to Wikipedia, the original Thunderbolt spec supports up to 10W of power. TB3 ups this to 15W and also allows USB power delivery, which can support up to 100W.
As for your LaCie drive, I assume that was particular to the model(s) you bought. Do you remember which specific model you had? Looking through the LaCie legacy product support pages, I found a few models that are bus-powered over Thunderbolt (1 and 2):
- Rugged Thunderbolt USB-C (datasheet)
- Rugged Thunderbolt USB 3.0 (datasheet)
- Rugged USB 3.0 Thunderbolt (Getting Connected page from the manual)
I did notice the Rugged RAID (manual) which says that “The power cable must be connected to an active outlet when using the USB 3.0 port” - so it can be bus-powered over TB, but not USB 3.
Yes, that’s the one I had, and you are quite right…I am remembering it the wrong way round. It was bus powered on TB2 but not USB 3. (I wonder why the LaCie LBD, which is TB2 only, needed wall power, perhaps because it had a fan). Apologies for misleading.
Perhaps. Or maybe because it has a pass-through TB2 port. If the specs require it to provide 10W of downstream power to that port, then it will need to use a power supply. (If it provides 10W downstream, and needs some power for its own SSD, then it clearly would need to draw more than 10W from the upstream computer, which would violate the TB spec.)
And, thanks to the power supply and pass-through port, you should be able to use it as a power-injector to let you connect other bus-powered TB2 devices to a TB3-based Mac (using the Apple adapter on the link between the Mac and the LBD).
Thanks! That all makes sense, but my LBD is long gone!