What is transit charging and how does it work?


power bank And USB-C hub The two devices are different; However, they have one thing in common called pass-through charging. In this article, we want to examine the reason for the importance of this type of charging and its advantages.

Pass-through charging allows a device connected to a power source to send current to other devices for charging. In other words, the device connected to the wall outlet passes electricity through itself so that other devices connected to it can be charged. This feature is mostly found in power banks (portable chargers) and USB-C hubs or docks, but it is not limited to these two types of devices.


In fact, with pass-through charging, the power bank and the device connected to it are charged at the same time, while USB-C hubs use some of the energy for their operation and transfer the rest to the connected device for charging.

In all these cases, the main advantage of pass-through charging is its convenience. For example, the number of ports on many modern laptops today is limited; Therefore, USB-C hubs with this feature, in addition to charging laptops, use a Type-C port to transfer data or video signals. In this case, the other ports of your laptop are free to connect to other devices.

USB hub

Likewise, let’s say you need to charge your power bank and phone, but there’s only one power outlet or you only have one charging adapter. In such a situation, thanks to pass-through charging, you can connect your phone to the power bank and the power bank to the wall charger. With this, both devices are charged simultaneously.

How does pass-through charging work?

As mentioned, USB-C power banks and hubs usually support pass-through charging. However, since these two devices are very different, the way they operate is also different.

Power banks with pass-through charging have a series of power regulating circuits that are responsible for matching the power required to charge the connected device and charge the battery of the power bank itself. Using a process called prioritization, the amount of energy needed by the connected device is transferred directly from the wall adapter to it. Now, according to the power required to charge the connected devices and the amount of power supplied through the adapter, the power bank is charged at its normal speed or at a lower speed.

In USB-C hubs or docking stations, this type of charging is a feature Power delivery (USB PD) is used to adjust the current and deliver the required power to the connected laptop, tablet or smartphone. However, this feature only works if the power supply connected to the USB-C hub and the device being charged both support USB PD technology. Otherwise, the hub may work while the connected device does not charge.

In addition, all USB-C hubs with pass-through charging capability can transfer a certain maximum power to the connected device and need a power supply that can provide a higher power. For example, the HP USB-C Mini Dock supports pass-through charging and can deliver up to 60 watts of power to a connected device. But for pass-through charging to work properly, it needs a 90-watt power supply.

Does this type of charging have any disadvantages?

Pass-through charging is a useful feature in both power bank gadgets and USB-C hubs; But it is not perfect and without problems, especially in power banks.

According to RavPower, one of the most famous manufacturers of power banks and chargers, high heat is the enemy of lithium-ion batteries used in power banks, and a power bank that is used to charge other devices while being charged takes a longer time to charge itself. So it heats up more and this more heat can shorten the life of the battery. With this in mind, it is better to use pass-through charging only when you have no other option. In addition, never trust power banks of unknown brands to use this feature.

The power bank is charging two devices

It is also better to know that pass-through charging is not as efficient as direct charging of the device by a wall adapter. Plus, if your mobile device from fast charging supports, you will not have the maximum charging speed; Unless the power bank supports exactly the same fast charging protocol. Some power banks even limit the current output to the connected device.

Do all power banks or USB-C hubs have pass-through charging?

Unfortunately, pass-through charging is not available on all power banks. Due to possible risks and additional costs required, many power bank manufacturers do not offer this feature. This feature is more common in USB-C hubs or docking stations. Although again not all devices support it, probably due to the additional cost that USB-PD technology entails.

All-in-one pass-through charging is a useful feature that can have many uses and make digital devices easier to use. If you plan to buy a power bank, docking station, or USB-C hub, check them for this feature.

Source link


Adib Zahedi is the CEO and Founder of He has nearly a decade of experience in IT, including two years spent working on a Youtube Chennal. He is also an author and writes articles for Has articles include tutorials and covers everything from Windows PCs to smartphone's software.

Leave a Reply

Your email address will not be published.

Back to top button