USB Power 101

Written by Vance Fitzgerald. Posted in Tech

  • Any USB cable (2.0 or 1.0) is composed of four wires—two for data and two for electricity.
  • The power is delivered across the outer two pins—a +5-volt wire and a ground.
  • USB connectors are configured to provide 100 milliamps of current through these pins when in “low-power” mode or 500 milliamps in “high-power” mode.
  • Although some USB connectors will provide maximum power without any questions asked, most won’t unless the USB device requests high power using the proper protocols.
  • Most USB hacks to power other devices aren’t that sophisticated, and are therefore limited to about 100-200 milliamps of current.
WARNING: An improper USB mod that results in a short circuit can fry your USB port or even your motherboard. Make absolutely sure that all wires are spliced correctly and that any exposed copper is covered with electrical tape or heat-shrink tubing.

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Vance Fitzgerald

Entrepreneur. Business Analyst with a passion for innovation, customer success & driving revenue.
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