iPhone 13 USB- C charging issues

jure240 wrote:

Okay, is this negotiation specific to iPhone 13, because it doesn't happen on iPhone 6s. Also sometimes my iPhone doesn't even recognize I plugged the charging cable in and it's not charging.

It’s specific on any device that is designed to use the additional capabilities of USB-C/PD. As your 6S was released 5 years before the PD spec was finalized it doesn’t know how to negotiate. The PD spec allows for this, and just supplies 5 volts by default unless the connected device asks for something different.

Which phone doesn’t recognize that the cable is plugged in, the 6S or the 13?

Carefully inspect the Lightning connector on the bottom of the phone; use a bright light and a toothpick to clean it (and a magnifying glass to be sure). Are you using an Apple USB-C power source, or a quality equivalent (Mophie, Griffin, Anker, etc).

When you charge with a USB-C PD power source the phone and the power source “negotiate” the voltage that the phone wants. This takes about a second. USB-C is the first source for charging devices that can supply more than one voltage, from 3.3 to 21 volts, making it a “universal” charger that can be used with phones, tablets, computers and other devices (I have a vacuum cleaner that charges with a USB-C charger, for example). Your iPhone 13 will fast charge with 7.5 volts (not amps), for example, and it tells that to the USB-C power source. When you use a USB-A power source, it can only supply 5 volts, so there is no negotiation required.

Want more detail about how the negotiation works?

The PD 2.0 specification allows the source (charger) to provide fixed voltages such as 5, 9, 12, 15, and 20V at a maximum allowable current to the sink (mobile device).

1. When the devices are initially connected, the source provides 5V over the VBUS.
2. If the source finds that it’s attached to a USB Type-C cable, it sends a Source_Capabilities message; a series of 32-bit power delivery objects (PDOs) specify each fixed voltage and maximum allowable current it can deliver.
3. The sink device (i.e., iPhone) responds with a 32-bit request data object (RDO) that indicates its desired source voltage and current.
4. As the cells are charged, the sink periodically renegotiates with the source to increase or decrease voltage and/or current. During each power transition, the sink is required to reduce power consumption to 2.5 W (pSnkStdby) until the source accepts the request and sends first an Accept and then a PS-RDY message.

I won’t further complicate it with the USB-C/PD 3.0 specification, which has a continuous range of voltages, not just the listed voltages above.

Then I suggest contacting Apple Support to discuss repair options. Use the Get Support link at the top of this page.