Fnirsi FNB58 USB Tester (Review)

    • by Jean-François Simon
    • Reading time: 2 min

    The Fnirsi FNB58 is a versatile USB tester for voltage, current, and energy measurements, with many advanced features. Let’s try it out!

    The Fnirsi FNB58 is a versatile USB tester capable of performing a wide array of voltage, current, and energy measurements, as well as supporting numerous fast charging protocols. This makes it an essential tool for diagnosing and testing USB devices.

    The FNB58 USB tester.

    Device Overview

    The FNB58 features multiple ports including USB C, USB A, and micro USB, and boasts a 2-inch LCD display for monitoring measurements. Its connectivity options are enhanced by Bluetooth for Android app integration and a micro-USB port for PC linking, providing flexibility in various testing environments.

    Testing Capabilities

    This device allows for the measurement of power supply parameters such as voltage and current, and can evaluate the power consumption of various USB-powered devices including smartphones and laptops. The FNB58 simplifies complex measurements that traditionally required manual intervention, making it easier and more practical, especially with USB 3 and USB C devices.

    Detailed Features

    The FNB58 is equipped with a high-resolution 2.0-inch TFT LCD. It connects to a PC via micro-USB and can communicate wirelessly via Bluetooth. It supports comprehensive data capture for voltage, current, capacity, power, and time statistics, and can measure both low and high-speed signals with its advanced internal architecture.

    FNB58 connectivity options
    The various ports and PD safety switch of the FNB58.

    It also features a dedicated PD negotiation chip for managing USB-PD communications safely and efficiently, and includes a unique safety switch to control power delivery negotiation, protecting connected devices.

    Measurement Ranges

    The FNB58 covers a broad measurement spectrum: Voltage from 4 V to 28 V (extending to 0 V with external power via PC connection), current up to 7 A, power up to 120 W, capacity up to 9999.99 Ah, and energy up to 9999.99 Wh. It can also measure cable resistance up to 9999.9 Ω.

    Menu Navigation and User Interface

    The device's user interface is navigated via a three-way joystick complemented by a separate back button, facilitating access to its diverse functions spread across multiple menu pages, including Compact View, Detailed View, Waveforms, and Applications. Each menu is meticulously organized to cater to specific testing needs and protocols.

    FNB58 display and controls
    User interface of the FNB58.

    Utility and Applications

    The FNB58 proves its worth in testing and diagnosing the performance of USB chargers and cables, offering detailed insights into their functionality and efficiency. This enables users to identify and address issues with their electronic devices effectively.


    Overall, the Fnirsi FNB58 is an indispensable tool for anyone involved with the maintenance, testing, or development of USB devices and power systems. Its comprehensive set of features, ease of use, and detailed outputs make it ideal for both professional and hobbyist applications in electronics.

    You can check out the Fnirsi FNB58 on our store by clicking here 



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