When a device shows a question mark

A tracked device normally shows its percentage on its icon. Sometimes it shows a blue question mark instead. That does not mean the device is disconnected: it means BatteryOnPC can see the device, but did not get a battery level out of it.

Reading the icon states

• A number in green, orange or red: the level, read normally.
• Grey, with a dash: the device is off, asleep or out of range. Nothing to do; it comes back on its own when the device wakes up.
• Blue, with a question mark: the device is there, but no level came out of it. A controller on a cable that reports no battery, such as a wired Xbox controller, shows the same way.

The first things to try

1. 1

   Wake the device up

   Move the mouse, press a key, put the headset on. Many wireless devices go to sleep after a few minutes and answer nothing until they wake up.

2. 2

   Reconnect it

   Unplug and replug the receiver or the cable, or try another USB port, ideally one directly on the PC rather than on a hub.

3. 3

   Check the category

   Windows sometimes files a device under the wrong type, and a receiver can look like a keyboard when it serves a mouse. If you added it under the wrong category, remove it and add it again with the right one.

When a device you have just added cannot be read, BatteryOnPC says so with a "Device not read" notification, and the Devices tab shows the same advice under the device's line.

When nothing helps

Then the likely explanation is that the device does not report its battery in a way BatteryOnPC knows yet. Each brand has its own protocol, sometimes one per product range, and a model can be missing even when its neighbours are supported. The compatibility page lists the models known to work.

Some devices report no level at all, through any channel. No program can invent one for them.

How anonymous diagnostics help

With the "Help add support for unrecognized devices" option on (Devices tab, on by default), a device that stays unreadable sends a technical description, once: its USB identifiers, the structure of its reports, and the app and Windows versions. No personal data, and nothing that identifies you or your PC.

The first time an added device is read successfully, a short note leaves too (model, connection type, level read), which tells us what works. That is how support grows from one version to the next, and new versions install themselves. You can turn the option off at any time.

Tell us the exact model

If a device matters to you, write to us from the contact page with its exact model name, usually printed under the device or on its box. A precise model saves a lot of guesswork.