# WattBench for FNIRSI FNB58 — USB power meter & cable tester > USB power meter & cable tester (iPhone/iPad app by Seth Egger.) - Source: https://appshunter.io/ios/app/wattbench-for-fnirsi-fnb58/id6816404264 (this page in markdown: same URL + `.md`) - Developer: [Seth Egger](https://appshunter.io/developer/6790598060) - Category: Utilities, Developer Tools - Price: $2.99 - Rating: 5.00/5 from 1 App Store ratings · 2 written reviews indexed - Age rating: 4+ - Requires: iOS 17.0 · 10 MB - Languages: American English, French (France), German (Germany), Italian, Japanese, Korean, Brazilian Portuguese, Chinese (Simplified, China), European Spanish, Chinese (Traditional, Taiwan) - Released: 2026-10-09 - Data updated: 2026-11-01 - User reviews in markdown: https://appshunter.io/ios/app/wattbench-for-fnirsi-fnb58/id6816404264/reviews.md ## What is WattBench for FNIRSI FNB58? DO NOT PURCHASE THE APP IF YOU DO NOT ALREADY HAVE THE FNB58 DEVICE. WattBench works only with the FNIRSI FNB58 USB meter. It is an independent app, not made by, affiliated with or endorsed by FNIRSI. WattBench turns your iPhone into a wireless display, data logger and test bench for the FNIRSI FNB58 USB power meter. Connect over Bluetooth and watch voltage, current and power live. See what your charger is doing on the USB data lines. Record a whole charge cycle with the phone locked. Then run guided tests that answer real questions: how much a power bank actually holds, how fast a phone really charges, and whether a cable is wasting power. LIVE • Big, glanceable voltage, current and power with peak hold • USB data lines: D+ and D− voltages and the meter's temperature • Charger detection: Quick Charge, USB PD, Apple, Samsung and BC 1.2 patterns named automatically • Chart of V, A or W, or All: voltage, current and power as three stacked charts on one time axis, each with its own scale • Full-screen chart up to the last 60 minutes, in portrait or landscape, with pinch to zoom and one cursor across all three charts • Trip counter for energy (Wh) and capacity (mAh) without starting a recording TESTS • Power Bank Capacity: compares what a bank really delivers with the mAh on its label • Device Charge: shows the fast, tapering and trickle phases of a charge, with a battery estimate • Cable & Charger Check: guides you through load steps with a USB electronic load and grades the resistance of the cable and charger • Data Cable Check: finds out in about a minute whether a USB cable can carry data or only charge, using a charger that signals on its data wires TWO METERS • Use two FNB58s at once, one before and one after a charger, cable or adapter (turn on Use two meters in Settings) • Efficiency: power in, power out, efficiency and the energy lost • Cable: the cable's resistance from the voltage drop between the two meters • Compare: two ports or devices side by side • Match Meters takes out the small offset between your two meters • Record both meters into one session, with both in the CSV and PDF report RECORDINGS AND REPORTS • Recordings keep running with the screen locked and survive a crash or a Bluetooth drop; dropouts are shown honestly as gaps • Lock Screen, Dynamic Island and Apple Watch Smart Stack show live readings while you record • Home Screen, Lock Screen and StandBy widgets show your latest recording or the one in progress; Control Center buttons start a recording or open live readings (iOS 18) • Automatic markers when the charger changes mode or voltage • Session reports with zoomable charts (V, A, W or all three stacked), range statistics, a power histogram, a voltage-versus-current plot, cumulative energy, temperature and D+/D− over time • Compare up to four sessions on one chart • Export PDF reports and CSV files ALERTS • Over- and under-voltage, over-current, over-power, current below, voltage drop, disconnect, over-temperature and "fast charge lost", with presets • Banners in the app, notifications in the background, with Stop & save during a recording PRIVATE BY DESIGN No account, no ads, no analytics, no network access. Your recordings stay on your iPhone. REQUIREMENTS The FNIRSI FNB58 USB power meter with Bluetooth. Turn Bluetooth on in the meter's settings menu, then tap Connect. A USB electronic load is recommended for the power bank test and the Cable & Charger Check. Two-meter mode needs a second FNB58. No meter yet? Tap Try Demo Data to explore every screen. User guide and test recipes: https://redthoroughbred.github.io/wattbench/guide.html ## Is WattBench for FNIRSI FNB58 safe? Not enough ratings yet to assess WattBench for FNIRSI FNB58. ## Is WattBench for FNIRSI FNB58 legit? WattBench for FNIRSI FNB58 appears legitimate, with a few gaps. The AppsHunter Legitimacy Score for WattBench for FNIRSI FNB58 is 65 out of 100 points across 7 verification signals from App Store and developer data. ## Recent user reviews (2 of 2) All indexed reviews: https://appshunter.io/ios/app/wattbench-for-fnirsi-fnb58/id6816404264/reviews.md ### 5/5 — Chain Breaker Review *2026-10-29* Hello, I was asked to try this program out and so far looking at it im impressed and will be filing a review video soon… stay tuned for the video review. ### 5/5 — absolutely useful *2026-10-22* not sure why I have overseen this app for my FNB58, but after I download and use, perfect, absolutely what I was looking for. Thank you **Developer response:** Thank you so much! You just made my entire week! Version 1.3 is waiting for approval now. I will update the docs to show new features but the main one is support for two FNB58’s at once. ## Version history (last 4 releases) ### 1.4.1 — 2026-10-31 WattBench now speaks your language. Along with English, the app is now in German, French, Spanish, Italian, Portuguese (Brazil), Japanese, Korean and Chinese (Simplified and Traditional): every screen, PDF report, widget, Live Activity and notification. It follows your iPhone's language; to use a different one for WattBench alone, open Settings → Apps → WattBench → Language. • Siri and Shortcuts phrases work in every language. • The USB data lines and the meter's temperature now use your region's decimal separator, like the other readings. • Fixes: Match Meters now allows for the small current a meter uses to run itself, and a meter that connects but sends no readings now tells you to switch it off and on. ### 1.4 — 2026-10-29 RECORDINGS • Stop a recording automatically after 1, 5, 10 or 15 minutes, as well as 30 minutes to 8 hours, or pick Custom and type your own number of minutes (1 minute to 24 hours). WattBench remembers the length you used last. • Tap the Saved notice on the Lock Screen to open that recording's report. PDF REPORTS • A new Export section in Settings: choose whether PDF reports include the meter's temperature chart and the session's Insights (power distribution, voltage against current, cumulative energy and the USB data lines), and switch reports to landscape pages. TWO METERS • The two-meter screen shows how to connect the meters for each mode, and Cable says which cable it measures. • On the Lock Screen, in the Dynamic Island, on Apple Watch and on the Mac, two meters now show the mode's number (efficiency, cable resistance or total power) and both meters' watts. DISPLAY • Choose Celsius or Fahrenheit in Settings for every temperature in the app, in reports and on the Lock Screen, or let your region decide. FIXES • If the meter keeps refusing to reconnect, WattBench now waits a little longer between tries instead of retrying nonstop, which saves battery during long recordings. • Connecting your meter while a demo recording is running now saves the demo recording first, so real readings never end up in it. • The Connect list keeps each meter in its place while it scans, instead of reordering by signal strength several times a second, so the row you tap is the meter you meant. With Show all Bluetooth devices on, meters stay at the top. • Two-meter readings no longer blink out for a moment between paired readings. • Two-meter recordings show the full energy in, out and lost (they read about a third low), and say when the meters don't look chained. • PDF report charts print enough decimal places to tell their scale marks apart when a reading barely changes. ### 1.3 — 2026-10-27 TWO METERS • Turn on Use two meters in Settings, then connect a second FNB58 and see both side by side. Put one before and one after a charger, cable or adapter. • Efficiency: power in, power out, the efficiency and the energy lost along the way. Cable: the cable's resistance from the voltage drop between the two meters. Compare: two devices next to each other. • Match Meters takes out the small offset between your two meters, so the difference you see belongs to what's between them. • Record both meters into one session, with both in the CSV and the PDF report, or record just one of them. • Tap a meter to see it on its own. No second meter yet? With Use two meters on, Try Two-Meter Demo in the title menu shows how it works. CHARTS • "All" now shows voltage, current and power as three stacked charts over one time axis, each with its own scale and unit, instead of three lines squeezed onto one unlabelled axis. It works the same on the Live card, in the full-screen chart and in saved sessions, with one cursor across all three when you touch and hold. • A flat supply stays flat: a chart's vertical span is never narrower than 2 % of the value, so the millivolt ripple of a 5 V rail is no longer stretched to fill the plot. • Full-screen chart: tap a metric chip to hide its row; the remaining rows share the space. • Saved sessions: "All" joins V, A, W, Temp and D± in the chart picker, and the span button that shows the whole recording is now called "Full". • The shaded area under the live chart follows the zoomed range instead of dropping to zero. DATA CABLE CHECK • A new test on the Tests tab finds out in about a minute whether a USB cable can carry data or only charge. Plug the meter straight into a charger that signals on its data wires, then plug it in through the cable: WattBench compares the D+ and D− voltages and names the result, such as data cable, charge-only or one data wire missing. • Works with Apple and Samsung chargers and most multi-port USB-A chargers, and with USB-A to USB-C or micro-USB cables; USB-C to USB-C needs a USB-C charger that signals. Lightning cables can't be tested. It checks the USB 2.0 data wires, not the USB 3 high-speed ones. • The result is saved with the recording and shows in its report and PDF. WIDGETS AND CONTROL CENTER • Home Screen widget in small, medium and large: your latest recording with its power curve, energy, capacity and test result, or the recording in progress with a running timer. • Lock Screen and StandBy widgets: energy at a glance and the recording timer. • Shortcuts widget: Record, Live, Power Bank and Charge in one tap. • Control Center buttons on iOS 18 and later: Start Recording and Live Readings. ALSO • A welcome sheet for new installs and a What's New sheet after an update. • Clearer prominent buttons, a Done button in Sessions, and About links to the user guide and the FNB58 web monitor for computers. ### 1.2 — 2026-10-09 No release notes. ## More apps by Seth Egger - [Repot: Plant Care](https://appshunter.io/ios/app/repot-plant-care/id6790598058) - [Wildcat Mesh](https://appshunter.io/ios/app/wildcat-mesh/id6816781840) All apps by Seth Egger: https://appshunter.io/developer/6790598060 --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-11-01.*