More ports!: Powering Thunderbolt Hubs with batteries

After a few people showed interest in having an option to mount their CalDigit Element Thunderbolt hub I came up with a solution. Shortly after I released the mount for it I had many people asking me about how people were powering the hub. I assumed most were using it on a cart setup or in a situation in which they had AC power since it requires power to function (as do all Thunderbolt hubs). If you’re using a laptop/tripod situation on location it’s best to just keep it simple and not have too many things connected at once. But some out there are maximalist so this might be something for them!

The CalDigit Element comes with a 150W power supply that’s larger than the hub itself. Now if using this at a desk or on a cart it's isn't a big deal but it does mean you need AC power.

The specs on the hub state that it requires 19V/7.89A or ~150W. But with all DC powered devices there’s typically some wiggle room.

In reality, unless you are using the PD(power delivery) output and all 7 ports on the hub you aren’t likely to ever hit 150W. But I wanted to know what it needed in a real world scenarios. So, I did some testing using my Kill-A-Watt and the power supply with a MacBook Pro.

I checked all of the following scenarios without PD to get a baseline for the hub and connected devices since PD typically varies from 0-65W on Macbooks in my observations.

  • Hub - No devices: 0.8W
  • Computer connected to hub: ~2.7W
  • 2 drives: (idle) ~8.9W
  • 4 drives: (idle) ~14-16W
  • 6 drives: (idle) ~17-18W
  • 6 drives: (writing) ~25-32W

(Note: That this would vary greatly depending on the computer load if using PD and peripherals connected to the computer.)

So, with this knowledge it made sense that this could be powered by a PD trigger cable. (I’ve covered these in the past: USB-C power all the things!) I have read about a few people using PD trigger cables with various hubs but wanted to do some testing for myself.
USB PD trigger cables can handle up to 20V/5A 100W and as you can tell by my tests above, 100W is enough to for those situations especially if you are not relying on PD from the hub.

Initially, I thought I’d need to splice a PD trigger cable with the proper DC barrel plug for the Element hub (which is known as a 7.4mm X 5mm DC barrel plug) But a quick search led me to a few options that already exist for this combo like this cable, as well as, some simple adapters to convert any 100W capable USB-C cable to a 7.4mm DC barrel trigger cable.

The 2M cable and adapter for any 100W USB-C cable.

One issue with the cable is that it's 2M long and that might not be ideal for some setups. With the adapters you can use any length cable you want. But if you''re the DIY type you could make a custom cable.

Once I had the adapter and cable I did more testing to confirm my thoughts. First I confirmed I was getting 20V with both a USB-C multimeter and my Fluke multimeter to confirm polarity.

With the basics confirmed I did the same tests as before and got the same results using a 100W PD power source and the PD trigger adapter.

6 SSDs with a range of specs in a range of enclosures.

I must say l that attempting to connect 6 SSDs via one Thunderbolt port is an extreme scenario and wouldn't yield a great real word experience due to bottlenecking. However, it still illustrates that both powering the computer via USB-C PD and the 6 attached drive is possible. If you want to read more about bottlenecking I've covered that here:  Bottlenecks: USB overhead and the Electric Light Company blog has who has covered the performance of multiple drives through a single Thunderbolt connection

Now, I didn't do extensive testing with hammering the computer with a heavy load but being that I saw a max of less than 40W with 6 drives and my Macbook was using and additional 10-20W during the tests for a total of ~60W max. There's not likely to be an issue when using a solid 100W PD power source. That being said, I would still rely on the Magsafe 3 for powering computer and use another PD source that's dedicated to the Element hub if I were trying this setup in the field.

I also made sure to test PD trigger adapter and cable with different PD sources that included a Zendure Supertank, UGREEN GaN charger and a custom V-mount to USB-C option I made. All did the job since they provide 100W PD.

Being able to power the CalDigit Element hub and similar ones like the OWC 5 port, Pluggable and Sonnet Echo 5 provides a fair amount of flexibility for certain scenarios and might be worth exploring. Especially since some of the others are specced at 100W. These cables and adapters are affordable and worth having on hand. They could save your butt if your power supply is missing or damaged. Just be sure you get the proper connector for your application. Not all of the hubs use the 7.4mm X 5mm connector.


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