Fnirsi FNAC-28 USB-Lade-Tester

FNIRSI FNAC-28 is a compact USB tester for measuring voltage, current, and power on USB-A and USB-C ports, supplemented with fast-charging protocol triggering. It is suitable for checking chargers, power banks, and USB cables, as well as measuring the charging performance of phones and other devices. The input connectors in male design (USB-A and USB-C) plug directly into the charger without any additional adapter, while the USB-A and USB-C output ports are bidirectional and the current direction is shown by an arrow on the display — this allows measuring both input and output on a power bank.

The tester measures voltage in the range of 4-24V, current 0-6.5A, and power up to 156W, always with 0.001-unit resolution. Accuracy is ensured by an external 16-bit ADC converter. In addition to instant values, it displays temperature, D+/D- data line voltage, and charging statistics — time, capacity (Ah), and energy (Wh) — in 5 independent data groups. It plots voltage and current curves with a time base of 0.1-5s/div; separate pages display data line behavior and VBUS voltage ripple with a base of 10-200µs/div, which helps identify a poor-quality source.

The fast-charging function can automatically detect protocols supported by the charger and trigger (request a specific voltage) the QC2.0 protocols (5/9/12/20V), QC3.0 (3.4-20V in 0.2V steps), FCP, SCP, AFC, VOOC/WARP, and SVOOC 1.0/2.0. The USB-PD protocol is not supported by the tester — with a PD charger it works as a regular meter, but it does not detect or trigger PD communication.

In the Toolbox section, it offers measuring the cable's internal resistance (comparison method with a reference measurement), DASH cable detection with reading of the e-marker chip, and Soft DASH and Soft Apple 2.4A modes, which set the data lines to 2.7V for full charging of older Apple devices at 2.4A. Via a separate USB-C port, the tester connects to a computer — the PC software records and exports measurement traces and is also used for firmware updates. Everything is displayed on a 1.06" color TFT display with wide viewing angles. The menu is in English. The plastic body measures 73x36x12 mm and weighs only 21g.

Important notice: After triggering a fast-charging protocol, the selected voltage is present at the tester's output — a connected device that cannot handle the higher voltage may be permanently damaged. No voltage higher than 24V must be applied to the monitoring ports, and no voltage higher than 16V to the PC port.