Many smartphone brands today promote ultra-fast charging technologies like 120W, claiming to charge a phone from 0 to 100 percent in just minutes. While this is convenient, such extreme charging speeds can impact battery life more quickly. Before buying a phone with high-watt fast charging, it’s important to understand both the benefits and the drawbacks.
Why does battery backup reduce?
A 120W charger pushes very high voltage and current into the battery, which puts significant electrical and thermal stress on the lithium-ion cells. Repeated exposure to this stress reduces the number of usable battery cycles. Research shows that fast charging accelerates wear and tear because the higher the heat and pressure on the cells, the faster they degrade. This is why users often notice reduced battery backup after just a few months.
How 120W charging harms the battery
High-wattage charging speeds up the internal electrochemical reactions inside the battery. While this helps charge the device quickly, it also forces the battery to work beyond its natural comfort zone. These faster reactions produce more heat, increase stress, and ultimately reduce the battery’s ability to hold charge. Over time, this leads to quicker deterioration of battery health.
Heat: the biggest enemy of battery life
Heat is the most damaging factor for lithium-ion batteries. When a device charges at 120W, the temperature rises much faster compared to standard chargers. Excess heat accelerates cell damage and reduces capacity. Tests have shown that batteries exposed to higher temperatures can degrade 20–30 percent faster than those kept at normal temperatures.
Impact on charging cycles
Every battery supports a limited number of charge cycles. Fast charging shortens this lifespan because the battery is frequently pushed into a high state of charge at high speed, which lithium-ion chemistry doesn’t prefer. As a result, in many cases, battery health can drop to around 90 percent or lower within 8–12 months of regular 120W charging.
How to use fast charging safely
• Avoid using 120W charging daily; use it only when necessary.
• Prefer slower charging (10W–30W) for regular use.
• Avoid charging overnight.
• Do not play games or use heavy apps while charging.
• Keep the battery between 20 percent and 80 percent for longer life.
