USB Charger Doctor - Inline Voltage & Current Meter Battery Tester

The USB Charger Doctor (KEWEISI KWS-V20) is a compact inline USB-A meter that shows what your charger and device are really doing. Plug it between any USB port and your cable to see voltage, charging current, capacity delivered and charge time on a clear backlit LCD.

Use it to check computer USB ports, phone chargers, car chargers and power banks, compare charging cables, or measure how much capacity a power bank actually delivers. It is powered directly from the USB port, so there are no batteries or external power needed. Just plug it in and read the display.

Features

• Displays voltage, current, capacity (mAh) and working time at the same time
• Measures 4 to 20V and 0 to 3A with ±1% accuracy
• Capacity counter up to 99999mAh and timer up to 99 hours
• Remembers capacity and time readings after power is disconnected
• One button reset (hold for 3 seconds to clear readings)
• Powered from the USB port, plug and play with no setup
• Compact and lightweight for your toolkit, desk or bag

Applications

• Testing phone, tablet and USB wall chargers
• Checking computer and car charger USB ports
• Measuring power bank output and real capacity
• Finding faulty or high-resistance charging cables
• Measuring current draw of USB powered projects such as Arduino and ESP32 boards

Display and Controls

1. IN: USB-A plug, connects to the output port of your charger or computer
2. RTZ reset button: hold for 3 seconds to clear the display
3. OUT: USB-A socket, connects to your charging or data cable
4. Voltage: output voltage reading, accuracy ±1%
5. Current: charging current reading (0 to 3A), accuracy ±1%
6. Capacity: capacity delivered (0 to 99999mAh)
7. Working time: time since charging started (0 to 99 hours)

Working time and capacity are kept in memory if power is lost, so readings carry on where they left off.

Specifications

Need USB-C or higher power testing? See our KWS-1902C USB-C Power Meter, which measures up to 30V, 5A and 150W.