Additional Tips Using a Multimeter: If you have a multimeter, you can also use it to check the voltage of a USB port by connecting it to the external pins of the USB-A connector.

If you're worried about an unknown USB drive, there's a way to test the device without risking your devices get overcome by a USB killer or worse.

USB-C power meter could save your devices from dodgy cables and chargers Plus, check the true mAh capacity of your smartphone, laptop, or portable battery.