FNIRSI FNB58 USB-C Fast Charge Tester 28V 7A 140W The FNIRSI FNB58 is a compact USB power tester for checking voltage, current, power, capacity, energy, charging protocol behavior, and cable performance across modern USB-A, Micro-USB, and USB-C charging setups. It supports up to 28V, 7A, and 140W monitoring, making it useful for fast-charge adapters, USB-C cables, power banks, phones, tablets, and small electronics power paths. The tester includes a 2.0-inch HD color display, high-speed refresh, multiple data pages, curve recording, offline data storage, and protocol detection for mainstream fast-charge systems. The Bluetooth Edition adds wireless data viewing support where compatible software is used, while the Standard Edition keeps the same core on-device measurement workflow. For simpler inline checks, compare it with the USB Charger Doctor Current Multimeter. For board-level power debugging, pair it with the UNI-T UTP1605S DC Bench Power Supply, the UNI-T UT61E+ Digital Multimeter, or an oscilloscope such as the FNIRSI 1014D Digital Oscilloscope. Technical Specifications Brand FNIRSI Model FNB58 Product Type USB voltage, current, power, and fast-charge protocol tester Available Versions Standard Edition and Bluetooth Edition Supported Interfaces USB-A, Micro-USB, USB-C Voltage Measurement Range 0 to 28V Current Measurement Range 0 to 7A Power Measurement Range 0 to 140W Capacity / Energy Supports mAh and mWh accumulation Display 2.0-inch high-definition color display Data Refresh High-speed refresh for real-time charging observation Fast-Charge Protocol Detection Supports mainstream USB fast-charge protocol identification Curve Display Voltage, current, and power curve display support Offline Storage Supports offline data recording and review Bluetooth Function Available on Bluetooth Edition variant Typical Use Charging adapter, cable, power bank, phone, tablet, and USB-C power path testing Integration Notes & Hardware Guidance Confirm the selected variant before purchase: the Standard Edition is for on-device testing, while the Bluetooth Edition adds wireless viewing support. Keep measured systems within the tester's 28V, 7A, and 140W monitoring range to avoid overloading the device. Use a known-good cable first when troubleshooting fast charging, then compare suspect cables under the same adapter and load conditions. Protocol detection results depend on the charger, cable, device, and trigger conditions; verify with an actual load when confirming fast-charge behavior. For current-limited bench experiments outside USB power paths, use a bench supply such as the UNI-T UT890D+ Digital Multimeter for independent voltage and current verification. Packing List FNIRSI FNB58 USB power tester × 1 Selected version: Standard Edition or Bluetooth Edition × 1 User documentation × 1 Retail package × 1 FAQ What is the main difference between the Standard Edition and Bluetooth Edition? The Standard Edition supports direct on-device testing and display. The Bluetooth Edition adds wireless data viewing support where compatible software is used. What maximum voltage, current, and power can the FNB58 monitor? The FNB58 supports monitoring up to 28V, 7A, and 140W within its specified measurement range. Can it test USB-C fast chargers and cables? Yes. It supports USB-C power-path measurement and can help compare charger output, cable voltage drop, current draw, and fast-charge behavior. Does it replace a bench multimeter? No. It is optimized for USB power testing. A multimeter is still recommended for independent measurement, continuity checks, and non-USB circuit diagnostics. Can it record charging data? Yes. The tester supports curve display and offline storage, allowing charging behavior to be reviewed after a test session.
