Reverse charging: Your phone can also be turned into a power bank!
As smartphones become increasingly powerful, a technology called "reverse charging" has gradually entered the public eye. It makes mobile phones no longer just power-consuming devices, but can also be transformed into "power banks" to power other devices. So, what exactly is reverse charging? How is it achieved? What are the practical application scenarios? This article will answer them for you one by one.
1. Technical essence: Reverse revolution of power flow
Reverse charging breaks the traditional mode of unidirectional power supply between electronic devices, allowing mobile phones to transmit power to other devices through wireless electromagnetic induction or wired interface, realizing "power sharing".
1. 1Wireless reverse charging
Hardware core: built-in bidirectional wireless charging coil + power control chip
Working principle: based on Qi standard electromagnetic field coupling, the direct current of the mobile phone battery is converted into alternating electromagnetic waves, and the receiving device captures and rectifies it into usable power through the coil.
Efficiency bottleneck: electromagnetic transmission loss is about 30%, and 10W output actually consumes 14W of mobile phone power.
1.2 Wired reverse charging
Hardware foundation: Type-C interface supporting USB PD protocol + Buck-Boost voltage regulation circuit
Workflow: mobile phone battery → DC-DC circuit (5V/9V/12V dynamic adjustment) → USB-C interface output
Efficiency advantage: power conversion efficiency exceeds 90%, and a 10000mAh mobile phone can charge headphones 4-5 times.
2. Application scenarios: rigid demand or pseudo demand?
Reverse charging is not a panacea, but it can solve urgent problems in specific scenarios
2.1 Emergency charging
When your friend's phone is out of power, you can use the reverse charging function to "extend its life" to avoid the embarrassment of losing connection.
2.2 Charging accessories
Charging low-power devices such as wireless headphones and smart watches, especially suitable for outdoor or travel scenarios.
2.3 Multi-device collaboration
In office or entertainment scenarios, power tablets, mice, keyboards and other devices to improve efficiency.
2.4 Environmental protection and energy saving
Reduce dependence on traditional power banks and reduce the generation of electronic waste.
3. Technical shortcomings of reverse charging
Despite the cool publicity, reverse charging still has three major flaws:
3.1 Unbalanced energy efficiency ratio
The overall efficiency of wireless reverse charging is only 60%-70%, and the mobile phone consumes 8W of power for 5W output, and the "premium loss" of power is significant.
Comparison: The conversion efficiency of ordinary power banks is about 85%, and the actual output of 10000mAh is 6000mAh; the reverse charging of mobile phones can only output 4000mAh.
3.2 Heat generation and life loss
When the output is continuously 10W, the temperature of the back panel of the mobile phone can reach 42℃-47℃, which accelerates the aging of lithium batteries (for every 10℃ increase in temperature, the cycle life decreases by 20%).
Actual measurement: After a flagship phone was reversely charged for 30 minutes continuously, the battery health decreased by 0.03% (an average daily decrease of 0.01% in daily use).
3.3 Protocol compatibility trap
Universality limitation: Only devices that support the Qi standard can be wirelessly charged, and private protocols such as OPPO VOOC and Huawei SuperCharge cannot be fully charged.
Power wall limitation: The wired reverse charging limit of iPhone 15 is 4.5W, and the wireless output of Samsung S23 Ultra is only 5W.
4. Precautions for using reverse charging
4.1 Ensure device compatibility
The device being charged must support wireless charging or wired charging.
4.2 Control usage time
Reverse charging consumes the battery of the phone and is recommended for emergency use.
4.3 Avoid overheating
Long-term use may cause the phone to heat up and is recommended for use in a well-ventilated environment.
4.4 Close background applications
When using reverse charging, close unnecessary background applications to save power.
5.Reverse charging: the power center of the future
Smartphones have evolved from tools to multi-device chargers. Although current models face efficiency and heat barriers, as technology continues to advance, reverse charging is expected to become a standard feature of smartphones in the future, bringing more convenience to users. Advanced technology will make reverse charging a standard. It is perfect for emergency situations or multi-device users, and is transforming from a novelty to an indispensable practical function.
