Why is Time Machine getting stuck partway through backups?

I think I have found the problem. My external G drive has a USBC connector. I had been using the drive for TimeMachine without problems by connecting to the Mac with the cable provided by the disk drive maker. But recently I began using a new USBC - USBC cable. I changed cables because my MacBook has spare USBC ports. So I moved the drive from my USB hub to a direct USBC connection to the Mac. Since then, I've experienced the erratic behavior of TimeMachine that is described in this forum. On a hunch, I changed back to the original cable and when the drive mounted, I opened it and deleted the partial file that was on the disk. TimeMachine now works properly. I suspect that the problem was caused because USBC is a new standard that provides variable power. My old G drive was expecting 5 volts. The Mac may be delivering the wrong voltage to the drive.