I am using a 2019 13-inch MacBook Pro with two thunderbolt ports. I have a WD My Passport external hard drive with a USB connection. In order to plug the USB into the Mac, I have a USB-to-thunderbolt adapter. However, the two thunderbolt ports on my Mac are so close together that I cannot use the power cable and the USB-to-thunderbolt adapter simultaneously.

When I try to back-up my Mac with the external hard drive using Time Machine, it says that "Time Machine can not back up because the computer is running on battery power. Connect the computer to a power outlet while your backup disk is available."

Am I missing something obvious here or is this a silly design flaw?

(1) How can I plug the Mac into a power outlet while simultaneously plugging in the external hard drive?

(2) Is there a way to override the Time Machine error so that I can just back up while on battery power?

Any help is appreciated.

1 Answer 1


This answer offers to possibly solutions.

Solution #1

One solution would be to purchase a different cable. One end should have a USB Type C plug. The plug on the other end depends on the drive you purchased. Below is an image of plug and port types.

You can distinguish USB Type A from USB 3.0 by color. If the port or plug is blue, then you have USB 3.0. If the HDD's existing cable has a USB Type A plug, then the new cable needs to be rated for a transfer speed of at least 480 Mb/s. Otherwise, the HDD's existing cable has a USB 3.0 plug. In this case, the new cable needs to be rated for a transfer speed of at least 5 Gb/s.

Solution #2

Use an adaptor cable instead of an adaptor. In this case, I would recommend a cable which is USB Type C male on one end and USB 3.0 female on the other end. This cable would be placed between the existing HDD cable and the Mac. This type of cable would be compatible regardless of whether the existing cable has a USB Type A or USB 3.0 plug. An example of such a cable is the Tripp Lite USB 3.1 Gen 1 (5 Gbps) Adapter Cable, USB Type-C (USB-C) to USB Type-A M/F, 6-in. Length,

  • Well done. But does the USB C cable not transfer 10Gb / s and the Thunderbolt 3 cable 40Gb / s? support.apple.com/de-de/HT208368
    – BabyBoy
    Apr 27, 2021 at 5:28
  • 1
    @DarwinOSX: The OP's drive transfers data at a maximum rate of either 480 Mb/s or 5 Gb/s. The problem is the plug on the cable that came with the drive is either USB Type A or USB 3.0, and needs to be USB Type C. USB 3.1 Gen 2 (10 Gb/s) and Thunderbolt 3 (40 Gb/s) are not being used here. Apr 27, 2021 at 8:50

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