What is the fast charging protocol?

The fast charge protocol is a battery charging technology that shortens the charging time of a device by improving charging efficiency. It does this by establishing a communication mechanism between the charger and the device, which allows the charger to adjust the output voltage and current according to the needs and status of the device. This communication mechanism is defined by the fast charge protocol, which determines how the device and the charger recognize and communicate with each other, and how to adjust the power output. By using the fast charge protocol, the device can charge as quickly as possible under safe conditions, rather than simply charging with the maximum possible current, which may cause the battery to overheat or damage.

Fast charge protocols usually include a handshake mechanism, which is an electronic dialogue process that allows devices (such as mobile phones) and chargers to recognize each other and charge at the correct voltage and current. The handshake phase occurs after the device is plugged into the charger, and the device and charger exchange information, including the fast charge protocol version supported by the device, the maximum accepted current, etc.

After the handshake is successful, the charger will adjust the output voltage and current according to the device's needs. For example, some devices can accept higher voltage and current when the battery is low for fast charging. Still, when the battery is close to full, the charger will reduce the voltage and current to protect the battery and extend its life.

It should be noted that different fast-charging protocols have different working principles. For example, some fast charging protocols may use more complex communication mechanisms, such as modulation/demodulation technology, to support more complex charging modes, such as constant current/voltage charging. Other fast charging protocols may adjust voltage and current based on the device's temperature, battery chemistry, or other factors.