5 Common Myths About Phone Charging: Misconceptions to Abandon in 2025
I. Myth 1: Overnight Charging Damages the Battery
Technical Principles and Experimental Data
Mainstream smartphone batteries in 2025 all use lithium-ion batteries, equipped with an “automatic power-off when fully charged” protection mechanism. Tests show that when a smartphone supporting AI intelligent temperature control (such as 2025 flagship models) is connected to the original charger for overnight charging (8 hours), the battery capacity decay rate is only 0.5% after 30 consecutive days. For older models without the protection mechanism (released before 2020), the capacity decay rate is 2.3% under the same conditions, which still falls within the industry standard of “monthly decay not exceeding 1%”.
Supplementary Daily Scenarios
Digital nomads often forget to unplug the charger after working at night, resulting in overnight charging of their phones. In actual use, as long as the original charger complying with QC5 or PD3.1 protocols is used, even if the phone is charged overnight for 7 consecutive days, there is no significant decline in battery health, and frequent plugging and unplugging of the charger is unnecessary.
II. Myth 2: Fast Charging Definitely Shortens Battery Life
Safety Design of Fast Charging Technology
Fast charging technology in 2025 has incorporated a “segmented charging” strategy: high power (e.g., 240W) is used before the charge reaches 80%, and after 80%, it automatically drops to 10-20W trickle charging. Tests show that for a smartphone supporting 240W fast charging, under the usage scenario of one full fast charge per day, the battery capacity retention rate is 89% after one year. For the same model using 20W regular charging, the capacity retention rate is 91% after one year. The gap between the two is only 2%, which is far lower than the wrong perception that “annual decay exceeds 20%”.
Comparison with Older Technologies
Fast charging technologies around 2018 (such as QC3.0) lacked temperature control design, leading to a 15% battery capacity decay rate after one year of continuous fast charging. However, 2025 models are equipped with AI intelligent temperature control chips, which can control the battery temperature during charging to 35-40℃, 8-10℃ lower than that of older models, complying with the requirement of “charging temperature not exceeding 45℃” in the IEC 62133-2:2023 battery safety standard.
III. Myth 3: All USB-C Cables Support Fast Charging
Differences in Cable Material and Specifications
USB-C cables supporting fast charging need to adopt 24AWG (wire diameter 0.51mm) oxygen-free copper cores, with TPE flame-retardant material for the insulation layer, and a built-in E-Marker chip for power identification. Tests show that fast-charging cables complying with the USB 3.2 standard can carry a current of 20V/5A (100W), while ordinary USB 2.0 USB-C cables (28AWG wire diameter) can only carry 5V/2A (10W). Forcing the latter to be used for fast charging will cause the cable temperature to rise to 65℃, posing a risk of burning.
Compatibility Test Data
Tests on 10 different brands of USB-C cables on the market in 2025 found that only 6 models can normally activate 65W PD fast charging. The remaining 4 models, due to the lack of an E-Marker chip, have an actual charging power of only 18W. Therefore, when choosing a cable, one must look for the marks of “supporting PD3.1” or “QC5 compatible” to avoid wasting the fast-charging function due to mismatched cables.
IV. Myth 4: Charging the Phone Only When the Battery Level is Below 20% Makes It More Durable
Characteristics of Lithium-Ion Batteries
The optimal cycle range for lithium-ion batteries is 20%-80%. Deep discharge (below 10%) will damage the structure of the negative graphite layer. Tests show that when the phone battery is charged within the range of 20%-80%, the battery capacity retention rate is 78% after 1000 cycles. However, if the battery is discharged to 0% and then fully charged each time, the capacity retention rate is only 52% after 1000 cycles, and the service life is shortened by nearly 30%.
Optimization of 2025 Models
Some 2025 smartphone models have added a “Healthy Charging Mode”, which can automatically pause charging after the battery reaches 80% and then continue charging to 100% when the user starts using the phone. Comparative tests show that for phones with this mode enabled, the battery health decreases by 0.8% after 3 months, while for those without it enabled, the decrease is 2.1%, further verifying that “shallow charging and shallow discharging” is more conducive to extending the battery life.
V. Myth 5: Using the Phone While Charging Causes Explosion
Risk Sources and Safety Protection
The main reason for the phone heating up while charging is the simultaneous operation of the charging chip and the processor, rather than “danger from use”. All 2025 smartphone batteries have passed the “needle pricking, extrusion, overcharging” triple safety tests. Tests show that even when playing high-load games continuously for 1 hour while charging, the maximum battery temperature reaches 42℃, which is lower than the safety threshold of 60℃. In addition, the phone body has a built-in overheating protection, which will automatically reduce the charging power when the temperature exceeds 45℃.
Hidden Dangers of Inferior Accessories
The real risk comes from non-original chargers. Tests found that the output voltage fluctuation range of inferior third-party chargers (without 3C certification) reaches ±2V, which is much higher than that of original chargers (±0.5V). The unstable battery voltage during charging may cause safety issues. Therefore, using the phone while charging is inherently harmless, but it is necessary to use a charger that meets national standards.
VI. 3 Key Practices to Extend Battery Life
Practice 1: Prioritize Using Original Fast-Charging Accessories
The original charger is fully matched with the smartphone battery parameters. For example, a certain brand’s 240W original charger in 2025 uses a GaN (gallium nitride) chip, with a conversion efficiency of 95%, which reduces energy loss by 7% compared with third-party chargers (88% conversion efficiency) and lowers charging heat generation.
Practice 2: Enable the Healthy Charging Function
The “AI Healthy Charging” function generally supported by 2025 models can avoid the battery being in a fully charged state for a long time during overnight charging by learning the user’s schedule. Tests show that after enabling this function, the time the battery stays fully charged is shortened from 8 hours to 1 hour, and the monthly capacity decay rate is reduced by 0.3%.
Practice 3: Avoid Charging in Extreme Environments
Charging lithium-ion batteries in an environment below 0℃ or above 40℃ will cause permanent damage to the capacity. Tests show that when charging in an environment of -10℃, the battery can only be charged to 60% and the subsequent capacity decay accelerates. When charging in an environment of 50℃, the battery protection mechanism will directly stop power supply. Therefore, when camping or traveling in a RV, avoid charging the phone in an environment of high-temperature exposure or low-temperature cold.
