Reverse charging: what it is, how it works and what it does
A charging mode that reverses the direction of energy flow, allowing a mobile device to act as a power source for other devices, with an output power of up to 29 W.
Definition
Reverse charging is an operating mode in which the direction of energy flow is reversed: instead of receiving current from an external source, the device outputs energy to charge another unit. In practice, this feature turns a smartphone into a portable power bank.
Operating principle
In a conventional charging cycle, energy flows from an adapter or the electrical grid into the device's battery. With reverse charging, the current direction is inverted: the phone's own battery becomes the power source and transfers energy to a second connected device. The documented output power for this mode reaches 29 W, enabling a reasonably fast recharge of the receiving device.
Applications
- Using the phone as an emergency power bank to charge earbuds, smartwatches, or other smartphones.
- Sharing energy between compatible devices without an external charger.
Scope and limitations
Reverse charging is constrained by the capacity of the source device's battery: while it powers another unit, the phone's own battery discharges. The output power (29 W in the documented implementation) determines how quickly the receiving device can be recharged, but it cannot exceed the total energy stored in the source battery.
Interpreting its presence in a product
When reverse charging appears in a device's specifications, it indicates that the device can function as a power source for other equipment. The 29 W figure allows the user to estimate the recharge speed of the connected device and compare the phone's capability as a power bank against a dedicated external battery.
The 29 W reverse charging turns your phone into a power bank.
Source: product specification (amazon.es, claims 3716 and 3717).