USB-C Tester: Charger & Cable

Find out why your phone charges slowly, which cable is throttling you, and exactly what your phone can do over USB-C.

USB-C Tester is a focused utility that combines the four checks every Android phone owner actually needs in one clean, ad-light app, without the fake "wattage" numbers, screen-spamming interstitials or paywall fragmentation you get elsewhere.

WHAT IT DOES

• Live charging meter: real-time voltage, current and battery-input wattage. The app works out the right units and scale from your phone's own live data, instead of relying on a list of known models that would get every unlisted phone wrong.
• Charger test: a clear verdict for any charger and cable combo. Save the result, name the cable, compare it next time. If your battery is too full for the number to mean anything, the app says so instead of guessing.
• OTG check: confirms your phone supports USB-OTG, then verifies it actually works when you plug a real device in.
• DisplayPort Alt Mode check: finds out whether your USB-C port can drive an external monitor, and confirms it the second one is connected.
• Cable library: keep notes on every cable you own, tag them by colour, see at a glance which one charges fastest.
• Charging session history: full voltage / current / wattage curves over time so you can see thermal throttling and PD renegotiation in action.
• Charge alarm: get a notification when the battery hits 80% or 85% to extend long-term battery life.
• Live wattage widget: see your current charging speed without unlocking the phone.

HONEST ABOUT LIMITS

Android does not expose the full USB Power Delivery contract to third-party apps without root. Some phones do report the ceiling they negotiated with the charger, which the app shows as the port maximum, but that is a limit and not a measurement. The wattage you see is measured at the battery, not at the wall. An inline USB power meter will always read higher, and that is expected.

Battery level is the biggest reason. Past roughly 70% your phone slows the charge down on purpose to protect the cell, so the same charger and cable can read over 20 W at 30% and under 10 W at 80%. Your phone also only draws what it needs, and conversion inside the phone costs a further 5 to 15%.

Anyone claiming to read true wall wattage on a stock Android phone is fudging the number. We label everything as "battery input power" so you always know exactly what you are looking at.

WORKS ON

Compatible with Samsung Galaxy S22 / S23 / S24 / S25, Google Pixel 8 / 9 / 10, OnePlus 11 / 12, Nothing Phone, Xiaomi 14, Motorola Edge, and most modern Android phones with USB-C running Android 9 (Pie) or newer. Works with any USB-C fast-charging setup, wattage is reported as the phone reports it.

PRIVACY

USB-C Tester does not collect personal data such as your name or email, and your measurements stay on your device. It uses Google AdMob for ads and Firebase Analytics for anonymous usage statistics. AdMob may use an advertising identifier subject to your consent choice and Android settings.

WHY THIS APP

Built by a solo developer tired of charging-meter apps that spam interstitial ads, fake their wattage readings, or only do half the job. USB-C Tester does exactly what it says: measures what Android actually exposes, is upfront about the rest, and gets out of your way.

Recent changes:
What's new in 0.1.18:

- Fixed: with an ad on screen, the Back button on the result, OTG and DisplayPort screens could become impossible to tap.
- The ad on the result screen no longer loads while a measurement is running, so its own power use cannot affect the reading.

Cables and history are kept.