USB-C charger doesn’t work?

USB-C (also called USB Type-C) is the newest data/charging connector standard for smartphones and laptops. We come across more and more USB-C charging problems in our daily work. Customers pop in with their USB-C charger saying that the charger works fine with other devices but doesn’t work with specific phone. Sounds weird? Yes. 

Remember: not all phone chargers which can fit into your phone charging port can charge your phone, especially for a USB-C phone. We try to explain in this blog.

There are two different types of data cable for USB-C shown below. The left adaptor and charger is the traditional USB-C (Standard USB to USB-C) which comes earlier that the right one, USB-C to USB-C. The traditional USB-C can deliver fast charge to your phone, but not as fast as the USB-C to USB-C one. That’s why more and more devices are adopting USB-C to USB-C solution.

USB-C charger
USB-C to USB-C charger

A smartphone battery is much more complicated than an ordinary AAA battery, and it’s not as simple technology to charge it. Below image shows the inside of a USB-C charger. You can see a lot of tiny pins of it. Among all these pins some are responsible for current flowing, and others are for controlling signals. 

usb-c charger

You might ask why there are signals for charging a smartphone battery and what are they for. Well, there is a circuit board on all smartphone batteries which controls how the energy material be charged and stores all kinds of information of the battery like vendor, manufacture date, charge loops, capacity percentage, voltage and charging speed etc. 

When a charger is put into the charging port of a smartphone, it doesn’t start to charge immediately. The USB adaptor needs to communicate and negotiate with the battery through the controlling signal pins as to how how current the adaptor should output. Only when the negotiation is successfully done, the adaptor can start to charge the phone. Any issue occurs during this process will prevent the charging. For example, you cannot charge a MacBook or a laptop with a normal smartphone charger. Because it can not output enough current for a MacBook/laptop battery. Current output is only one of the causes that stop the charging. 

Firmware bugs or incompatibilities can also make this happen. 

Well developed firmware should always accept all chargers that can fit into the smartphone charging port. But some vendors don’t bother to update it for new technologies. For example, if a smartphone was developed to work with USB-A to USB-C charger but doesn’t upgrade to support UBS-C to USB-C, it will not charge with a USB-C to USB-C charger. And what’s more, bad firmware development can even enter dead loop when put a USB-C to USB-C charger in. When this bug is triggered, we will have to restart the phone to make it work with a standard USB-C charger. I’m not telling this theoretically, but we actually met this situation.

So, if your charger doesn’t work properly, it might not be broken. There might be a protocol issue between the charging adaptor and your smartphone. The best strategy is to use the official charger and adaptor. If any one of them is broken, buy the same type to replace it. To make it clear, for example, if the standard USB-C charger is broken, buy another USB-C charger to replace the broken one. Don’t buy a USB-C to USB-C charger and a USB-C adaptor.

Thank you very much and congratulations that you can reach this line, which means you have not only strong background in technologies but also great curiosity in knowing how things work. And as our technician was a former hardware/firmware engineer with more than 20 years experiences in this field, he is in such a habit to explain things to this level.

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