"Unplug the accessory using too much power to re-enable USB devices."

When trying to charge my Mac this comes up.. USB Accessories Disabled.. Unplug the accessory using too much power to re-enable USB devices. I am only using my cable to charge it. Consequently I can’t charge.

Re: "... there doesn't seem to be an obvious way to identify which specific USB device it thinks is using too much power"

Unplug them all, then one at a time, operate with each, just that one, to find the faulty device. Sooner or later, assuming the alert was not an anomaly, you'll find the faulty one.

If you don't, then you may have another problem that requires researching and/or service.

Hi CliffYorkie.

Your description of the problem you are experiencing does not make much sense, please review the following comments and then rewrite your question accordingly.

You have appended your question to an existing forum topic that resides in the Mac desktop computers category and is discussing powering external USB devices from a USB or Thunderbolt port, there is no battery in a desktop Mac to charge, are you perhaps discussing charging a MacBook?

If you are discussing a MacBook where are you plugging in the charging cable?

A MacBook is charged via a dedicated charging port, it is not charged via a USB or Thunderbolt port and plugging in a charger via a USB or Thunderbolt port will most likely damage a MacBook.

If you are plugging in a charger via the dedicated charging port on a MacBook and you see the message as described are there any other external devices connected via USB or Thunderbolt? If applicable disconnect them and leave them unplugged, unplug the charger, wait for a few minutes then reconnect the charger, leave the MacBook switched off for approx half an hour and do not plug in any external USB or Thunderbolt devices while charging, then restart the MacBook, does the message disappear and full charging resume?

Assuming you are discussing a MacBook, have no external USB or Thunderbolt devices connected and the message appears when plugging in the dedicated MacBook charger via the dedicated charging port then the charger might be defective or the power board that supplies the USB/Thunderbolt ports is defective and you should arrange to visit a local Apple shop with your MacBook and charger to have them both checked over by an Apple technician.

The above questions and suggestions are based on the assumption that you are discussing charging a MacBook and not a rechargeable accessory plugged into a USB or Thunderbolt port, such as a rechargeable keyboard or mouse or an iPhone or iPad.

If the problem you are trying to resolve is something else please clarify precisely what the problem is so that we may be better able to offer support.

HTH

Will.