Not everyone will need this — and I won’t use it regularly — but you may: Plugable’s second generation USBC-VAMETER Voltage and Amperage Meter.
It’s a portable USB-C multi-meter that allows users to see how fast a USB-C device is charging. The USBC-VAMETER — roughly the size of a USB flash drive — measures three points of information: voltage, amperage, and the direction of the electrical current.
The second generation meter boats an updated OLED display that’s brighter and easier to read. And a new orientation button lets you flip the screen 180 degrees, which can be convenient.The USB power meter can be connected in either orientation, allowing for the full range of USB Power Delivery voltage from 5 to 20V (4-20V, 50mA-10A operating range). Used as a data and power quality meter, it allows USB data pass through, USB-C Alt Mode video, USB-C charging. Use inline with USB-C docking stations, chargers, accessories, etc. Not compatible with Thunderbolt 3 devices.
However, as Plugable notes, the meter is designed for quick and easy measurements. It’s not meant to replace professional USB-C test equipment to fully replace professional USB-C test equipment.
The USBC-VAMETER is now available for purchase on Amazon.com for US$29.95 with a $6 off launch coupon. The USBC-VAMETER is also available on Amazon in Canada, Singapore, Japan, Australia, and the UK and on Walmart, eBay, and Newegg.