Today, we generally use USB ports as the standard connector for various types of peripherals on our PCs, be it printers, mice, keyboards, microphones, etc. One of the advantages of these ports is that they can also supply power to said peripherals, making a power supply unnecessary.
Small reminder on the USB port
The USB port is a high speed serial port which among its peculiarities is the fact of incorporating a charging pin which is used to power the peripherals. This feature is found in all USB ports regardless of their form factor and is one of the biggest attractions it has, reducing the amount of power we need to have around our computer.
This enables what we traditionally call hot-plugging or hot-plugging, which allows you to connect peripherals while the PC is running and the operating system not only recognizes them, but can also use them without problems immediately. and without restarting. This capability is also known as plug & play or connect and go, but it often happens that the USB port does not give enough power and therefore the device usually comes with an external power supply.
Other times it depends on the specifications of the USB hub, not all of them give the same wattage and have the same capacity, so we can see that a specific USB port does not have enough power.
What is the power of the USB ports on my PC?
To check this, we don’t need to install any new software and we don’t need to use any special hardware for it. Just type the following into the Windows search bar: devmgmt.msc. This will bring up the device manager.
Once you’re there, select Universal Bus Controllers, double-click and then select the USB Root Hub, but do so with the right mouse button selecting properties. The following window should appear:
In the same properties window of the USB root hub, select the details and in the drop-down menu of this tab select “Energy data”, which will give you information on the amount of electrical energy transmitted by the root hub to the different devices. It goes from D0 to D3, D0 being the one that gives the most energy and D3 the one that gives the least energy.
Why do USB ports use multiple power modes?
Keep in mind that the USB port supports different states depending on the situation the devices are in. These modes indicate how much power said device needs at this time. For example, a device that falls asleep won’t need as much as an active device. A device is also not disabled in the same way as it is disconnected from the USB port.
This is why USB hubs use state machines that distribute power to different USB ports based on state, in general and unless we are using a USB-C port with fast charging, the specs are the following:
- A USB device with a battery can use up to 500mA to charge it, which means it can consume 2.5W of power to charge these devices.
- If the device is in standby, the USB port is operating at 2.5mA.
- The voltage between the different ports does not add up, but the amperage does.
It may happen that despite the fact that the USB root hub is specified for a certain level of power, but due to a problem in the controllers, the power transmitted to the USB ports is much lower.
To check it at the software level, we will use USBDeview, a completely free and easy to use application, which has one version for x86 processors with 64 bit support and another for 32 bit processors. Check your PC’s processor first to download the correct version. This will come to you in a Zip that you must unzip to a folder.
You can use any unzip application to unzip the whole folder, once there double click on the file USBDeview.exe. This will launch the app, so it will be completely portable and you can use it on any PC.
Move the bottom bar of the window to the right until you find the Power column, where you can get the consumption of the peripheral side, from there you can check how many milliamps each device connected to the USB ports is consuming .
USB devices consume power in blocks of 100mA for USB 2.0 devices and 150mA for USB 3.0 devices. So we can check if the devices are getting enough power.
Use a USB voltmeter
The third option to check if the USB ports are providing enough power is to use hardware. Don’t worry, you won’t have to open the computer for this, but just use a USB voltmeter like this:
You just need to connect the voltmeter to the USB port you want to measure and it will automatically give the information of the USB port you want to measure. And in case you want to measure a USB C port, you can choose the following option:
With them, you will be able to check whether the USB ports on your PC are working properly when powering on the devices. They will also help you check if the problem is with the devices and how much power they are consuming.
A recommendation we make is to test the USB voltmeter on other PCs or devices with this type of ports and compare them with the ones you get on your PC to check if the power supplied by the USB ports to each device and device is adequate and therefore the requested by the devices themselves.