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USB-C was touted as the 'be-all-and-end-all' of USB connections. One size fits all, reversible plug, lightning fast data, extremely powerful charging and even video support. But the reality is a little more complicated. USB-C may support all of these features - or none of them - at the hardware manufacturers' discretion. In its most simple form, a USB Type-C socket may only require or provide the equivalent of USB 2.0 specifications from two decades ago! And you can't tell from just looking at it.
If you have a device with a USBC socket for charging, and a USBC to USBC cable isn't working, just try a USB Type-A to USBC cable. It probably shipped with one in the box.
Want to know why? Read on...
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USB Type-A to USB Type-C Cable
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USB Type-C to USB Type-C Cable
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USB 2.0 (and even 3.0) hardware provides power at 5V, typically between 0.5 and 2.1 Amps. This power flows in a single direction, from your charger or computer into a peripheral device, like a flashlight or smartphone. The power is simply provided, and its up to your device to use it or not.
USB-C can now offer in excess of 100W in a wide combination of Volts and Amps. Compared to 5V/1A of USB 2.0, Type-C can now exceed numbers like 20V/5A. That's a TON of power by comparison, and ensuring devices negotiate a safe charging level is critical to prevent exploding gadgets. That means USB-C devices and cables include special pins and electronics to achieve what USB 2.0 and 3.0 will never support.
If your device has a USBC socket that is missing those special electronics, the fail-safe is that no power is provided at all.
Another thing to look at is your source device. Some USB-C ports are data-only, and don't provide power at all. This can be the case with USB-C ports found on some laptops and docks, where only specific ports are designed for PD charging. So let's take a look at USB PD, too.
USB-C to USB-C cables are designed with USB Power Delivery (PD) in mind which is a technology standard that allows devices to transfer significantly higher levels of power over a USB connection (eg. 9V, 12V, etc). However some devices don't support PD, meaning they can't properly communicate with a USB-C power source and may refuse to charge.
For example, some low-power accessories, such as wireless earbuds, fitness trackers, and certain older smartphones, may not implement PD at all. These devices expect a basic 5V supply, which is always available from a USB-A port but may require negotiation from a USB-C port. If the negotiation fails, the USB-C charger may never provide power.
Another issue is that some power adapters only support PD, meaning they won't deliver any power unless the device explicitly supports PD as well. If a device relies on older charging standards, it might not work with a pure USB-C PD charger.
For a USB-C device to tell a charger it needs power, it must have 5.1 kΩ pull-down resistors on its CC pins to allow it to properly identify and configure the connected device. So what does this jargon mean? Well a pull down resistor is a resistor placed within a USB device that actively pulls down the voltage on specific data lines towards ground (low voltage) ensuring a defined state when the line is not actively driven by the device. This prevents a floating state on these data lines where voltage is indeterminate which can lead to communication issues between connected devices.
Some budget or non-standard devices do not include these resistors resulting in them being ignored by USB-C power sources. No handshake = no charging. This issue is commonly seen in budget accessories, wireless chargers, and even some older USB-C devices that weren't designed to follow USB-IF specifications strictly.
Because USB-C to USB-A cables always provide a default 5V without requiring negotiation, they can bypass this issue entirely. That's why your device might charge with a USB-A to USB-C cable but not with a USB-C to USB-C cable.
USB-C devices must decide who provides power and who receives it. But if both devices expect to be the host (or neither wants to be), they get stuck in a stalemate and nothing happens.
Because USB-C to USB-A cables always provide a default 5V without requiring negotiation, they can bypass this issue entirely. That's why your device might charge with a USB-A to USB-C cable but not with a USB-C to USB-C cable. Since USB-A is always the power provider, a USB-C to USB-A cable avoids this issue entirely.
Some USB-C to USB-C cables are designed only for data transfer and lack proper charging capabilities. If your device expects a charging signal and doesn't get one, it won't charge.
Additionally, some USB-C cables are designed for high-speed data transfer (e.g., USB 3.1, USB4, Thunderbolt 3/4) and may have different internal wiring than basic charging cables. If a device expects a charging-capable USB-C cable but gets a data-only one, it won't charge.
Many pre-USB-C devices use proprietary charging methods (e.g., Qualcomm Quick Charge, Apple 2.4A, Samsung Adaptive Fast Charging). Some USB-C to USB-C cables don't support these older standards, while USB-C to USB-A cables often do.
Some manufacturers skip adding pull-down resistors to cut costs, assuming users will stick to the included cable and charger. Others don't fully test their devices with third-party USB-C accessories, leading to unexpected compatibility issues.
Additionally, some companies assume customers will use USB-C to USB-A charging instead. This is why certain budget devices are still built to expect older USB-A power sources instead of modern USB-C PD chargers.
USB-C is powerful, but it's not always plug-and-play. Power negotiation, missing resistors, legacy charging methods, and host/client confusion can all lead to USB-C to USB-C incompatibility, even when USB-C to USB-A works fine.
Now that you know why your USB-C device won't charge, you can troubleshoot more effectively and avoid unnecessary frustration. Next time your USB-C to USB-C cable fails, don't panic, grab a USB-A adapter, and you'll likely be back in business.
If we've missed something or you have any questions, we'd love to hear from you! Contact Us
