USB Meter Web

Live readings from your Bluetooth USB tester, in the browser

Not connected

Help

Plug in the meter, then choose Connect and pick it from the list.

Meter not in the list? Unplug it, plug it back in and choose Connect again right away. Some meters can only be found shortly after they get power. Still missing?

Time range

Totals

Capacity
– mAh
Energy
– Wh
Elapsed
–

About this viewer

Many cheap USB testers have Bluetooth, but their phone apps are slow to pair, full of ads or no longer updated. This page reads the same Bluetooth stream directly and puts every reading on one dashboard: voltage, current, power, temperature and the USB data lines each get a graph, all on the same time axis. Move the pointer over any graph to read every value at that moment, and download the whole recording as CSV or as a ZIP made for AI assistants. There is nothing to install and no account.

How to use it

  1. Open this page in Chrome or Edge.
  2. Plug the meter between a charger and the device you want to measure. If it was plugged in already, unplug it and plug it back in: some meters, the J7-C among them, can only be found shortly after they get power.
  3. Choose Connect to meter straight away and pick the meter in the list. A J7-C shows up as UC96_BLE, ATorch meters under their model name, such as UD18-BLE or AT24-BLE. Readings start at once.

Analyse a recording with AI

Export for AI downloads a ZIP with two files: your readings as CSV and a README that tells an AI assistant what was recorded, what every column means, what a meter like this can and cannot measure, and how to analyse the kind of test you ran: a charging session, a charger, a power bank, a cable or the power draw of a device. Give the ZIP to Claude, ChatGPT or another assistant and ask your question, for example how long the charge took, whether the charger held its voltage, or how much a power bank really delivers. If the assistant does not take ZIP files, unpack it and give it both files.

The README is written in English. Ask in your own language and the assistant answers in it.

The page still sends nothing anywhere. The file goes only where you put it.

For Claude there is also a skill with the same guide, so Claude has it at hand even when it gets only the CSV. and add that ZIP to Claude (how to add a skill).

Supported meters

Meter Type Status
J7-C USB Checked against frames recorded from a real J7-C
ATorch UD18 and other USB meters of the same family USB Checked against published sample packets
ATorch AC meters (AT24, AT3010) AC mains Checked against published sample packets
ATorch DC meters (DT24, DT3010) and other models using the same protocol DC Experimental: voltage, current, power, temperature and time. Capacity and energy are not decoded yet

If your meter connects but no readings appear, please open an issue with its name and model.

Browser support

The page uses Web Bluetooth, which Chrome and Edge provide on Windows, macOS, ChromeOS and Android. On Linux, Chrome keeps it switched off: open chrome://flags/#enable-experimental-web-platform-features in Chrome and enable that flag first. Firefox and Safari (including every browser on iPhone and iPad, except apps such as Bluefy that add Web Bluetooth) do not support it.

Privacy

Everything happens in your browser. The readings are kept in memory while the page is open and are never sent anywhere. There are no cookies, no analytics and no ads. Like any website, the page is delivered by a hosting provider, which sees your IP address when you load it.

Questions

The meter does not appear in the list.
Unplug the meter, plug it back in and choose Connect to meter again straight away. Some meters, the J7-C among them, can only be found shortly after they get power, so one that has been on for a while stays out of the list.
If that does not help: the list shows a meter only while the browser can hear it, so the meter needs to be nearby, with its Bluetooth switched on and no other connection. Disconnect it from any phone app or other tab first, because these meters accept one Bluetooth connection at a time. On Windows and Linux, make sure Bluetooth is on.
The list also leaves out devices that do not look like a supported meter. If yours is still missing, cancel the list and choose Show all Bluetooth devices. When the page does not know the name of a meter connected that way, it says so, and an issue with that name gets it added.
Why does it say the checksum is not verified?
Some meters, the J7-C among them, use a different checksum from the ATorch one. The readings are still shown when the frame is otherwise well formed.
Can it reset the counters or change settings?
Not yet. The viewer only reads.

Export for AI

Downloads a ZIP with your readings and a README that explains them, ready to hand to Claude, ChatGPT or another AI assistant. Say what you measured, so it knows what to look for.