I'm using a Macbook Pro 15" 2018 model. I want to use wired Internet connection with it. I've tried using 2 different USB-C hubs to accomplish this, both are USB-C to Ethernet plus some USB-A 3.0 ports (SD card reader slots on one of them). They both drained the battery life on my Mac by a lot, like roughly halved it or so even though I only used the Ethernet port on them.

Today I also got a pure USB-C to Ethernet adapter (not a hub). It seems to not drain the battery as much as the hubs but still has the same problem. I was hoping it would be better and I'll test it some more tomorrow.

The thing is that without the Internet connection through a USB-C to Ethernet port the battery life is just fine. It seems that it's as good as advertised, actually, more like 10 hours or so. I haven't done a real test to see how long it actually lasts before it shuts down, but it's still significantly better. Even Wi-Fi seems to use less power than USB-C to Ethernet.

Does anyone know a solution to this? Are USB-C to Ethernet connections on Mac bound to drain battery? Or could it be a software issue? I've tried searching the Internet a lot for a fix but it seems like a lot of people don't even have this problem with these kinds of adapters.

Thank you so much for any help, and kindest regards.

  • I am using a USB-C to RJ45 Ethernet adapter (Club 3D CAC-1500) and it seems that it drains the battery even when the MBP is on sleep (or more likely it prevents sleep). So I always have to pull the cable... May 8, 2021 at 9:07

1 Answer 1


It might be possible that some software is using up battery power. It can be checked in Activity Monitor under the Energy tab.

Under same app usage, ethernet adapter consumes more power.

The Ethernet dongle can be using up to 2.5 watts, that's 2500mW.....native ethernet connections typically use a lot less, but the dongle to ethernet requires MORE power, ..hence more power out when using the AIR thru the ethernet dongle.

Wi-Fi in GENERAL consumes between 10 mW and 800 mW (transmitting full bandwidth); NATIVE Wired ethernet consumes 200mW to 1W

Source: https://discussions.apple.com/thread/5194898

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