I have been testing a new keyboard setup with my iPad and found a disturbing occurrence. I’m using my HyperDrive 6-in-1 USB-C dongle with my iPad. It gives me a USB-C port, a USB-A port, SD and micro SD card slots, and an HDMI port. It can get warm during use, especially when I’m using my wireless dongles. So many dongles, dongles on dongles! A wireless dongle for my keyboard and one for my trackball. Between the two, I’m, carving through my battery power at record speed.
However, I was surprised to find that the wireless adapters may not have been the problem, or at least not my sole problem. Simply attaching my USB-C drive to my iPad started to drain the battery. I decided to do a quick test and, sure enough, having a USB-C hub plugged in, doing nothing, drains the battery three times faster than not using the adapter.
Testing the Battery Life
To test my theory, I decided to connect a USB-C to USB-A adapter to my iPad mini. I’d let it sit with that for a few minutes, awake, then see how low the battery dipped. I’d charge it up and then try without the hub. I’d also track how long it took the battery to drop from 100% to 90% My theory was that the USB-C hub uses more power all on its own. Looks like I was right.
| No USB-C Hub | USB-C Hub Plugged In | |
|---|---|---|
| Time to 90% | 60m | 22m |
| % Battery after 10 minutes | 100% | 97% |
| 2nd try, % @ 10m | 100% | 98% |
The results were consistent. The battery drain from simply plugging in the USB-C dock, nothing else lead to a nearly 3x drain in the battery life. Battery life on my iPad mini dropped from 100% to 90% in 22 minutes with the USB-C hub in. That took a full hour without the hub. All tests were conducted with the iPad screen on, doing nothing on the iPad, and with it showing my home screen.
My battery usage showed “USB-C Accessories” drew as much power, if not more power, than the apps I was using while using my USB-C hub. It’s clear, the hub alone draws significant power.
What Does This Mean For My Workflow?
USB-C hubs are great. I’ll continue to use them, especially when I need both a mouse and a keyboard attached to my iPad. However, if you’re not using your USB-C hub, unplug it. These use power just to sit there. I have another theory that this is worsened by devices that have an HDMI port, but, as I don’t have a USB-C hub without the HDMI port, I can’t prove that. What I do know is that these hubs use power, even with nothing attached to them. So, continue to use a USB-C hub when you need to transfer files from an SD card or when you need to plug in your keyboard. But don’t leave them plugged in.