Fast charging is not as fast as possible. The hidden dangers of high-power fast charging are not just explosions

Among the recently released mobile phones, Black Shark 3 supports 65W fast charging. Another news said that the upcoming Red Devils 5G mobile phone also supports 65W fast charging. If the realme X50 Pro is added, multiple Snapdragon 865 flagship phones use 65W fast charge.













Before that, 65W fast charge was only used by OPPO. This year, more mobile phone manufacturers use 65W fast charging, the ultimate goal is to make charging faster. On the surface, the charging speed of 65W fast charge is really fast, which can shorten the charging process to less than half an hour. As everyone knows, fast charging is not as fast as possible. High-power fast charging has some hidden safety hazards.





High-power fast charge faces the risk of battery explosion

A very simple technical principle, the greater the fast charging power of the mobile phone, the faster the charging rate, and the greater the risk of battery explosion. Because of this, the mainstream fast charge technology of mobile phones remained at about 40W last year. This year, flagship phones used 55W fast charge, and a few brands used 65W fast charge.





Last year, Xiaomi once showed 100W fast charge, and vivo showed 120W fast charge. However, 65W fast charge is currently the bottleneck of mobile phone fast charge technology. To put it plainly, the greater the fast charge power, the greater the risk of battery explosion. How to minimize the explosion risk of high-power fast charge is the key to commercialization of high-power fast charge.





At present, both the 65W fast charge of OPPO and the 65W fast charge of Black Shark 3 mobile phones use dual cell technology. As we all know, most mobile phones are single cells, and only a few mobile phones like iPhone X are dual cells. These dual cell cores for mobile phones that support 65W fast charge technology are designed to reduce the risk of battery explosion during high-speed charging.





Compared with single cell, what is the difference between dual cell charging? Generally speaking, 65W fast charging is to divide the charging power of 65W on two cells, which can reduce the charging power of single cell. According to the average apportionment, the charging power of a battery cell is only 32.75W, which is a very safe range. However, if there is a problem with one of the cells, the cell phone battery still faces the risk of explosion.





The price of high-power fast charging is at the expense of battery capacity

In many people's opinion, faster charging with higher power can shorten the charging time of mobile phones. As everyone knows, the price of high-power fast charging is the expense of battery capacity. Frankly, this approach is a little bit worthwhile.





From a technical point of view, the greater the power of mobile phone fast charging, the smaller the battery density. So, what is the relationship between battery density and battery capacity? For a battery with the same volume, the higher the battery density, the larger the battery capacity. Therefore, Apple's mobile phone battery looks very thin and has a larger battery capacity than other mobile phones. This is because Apple ’s mobile phone has a higher battery density.





In order to ensure battery safety, the density of mobile phone batteries that support high-power fast charging cannot be too large. In other words, with the same battery volume, the larger the fast charge power, the smaller the battery capacity. For example, OPPO Find X2 supports 65W fast charging, the battery capacity is only 4260mAh, and the capacity of a single cell is only 2130mAh. You know, this year's Snapdragon 865 flagship, the battery capacity is above 4500mAh.





Compared with 4G mobile phones, 5G mobile phones are thicker and weigh more than 200g, which is quite heavy. If the phone supports faster charging with greater power, the only way to keep the battery capacity constant is to make the battery larger. As a result, the mobile phone will be thicker, which is difficult for consumers to accept.







For many years, Apple mobile phones only support 18W fast charging, not because Apple technology is backward, but because to maintain the thinness and lightness of the iPhone appearance, the use of higher power fast charging requires sacrificing battery capacity. In addition, the density of Apple's mobile phone battery is too large, and there are too many technical problems to be solved using high-power fast charging.

Conclusion

Although the high-power fast charging of mobile phones has solved the risk of battery explosion, this technology, sacrificed for battery capacity, does not greatly improve the user experience. Indeed, 65W fast charge increases the charging speed, but the battery is less durable; 40W fast charge has a slower charging speed, but the battery is more durable. Needless to say, like other technologies, fast charging technology also needs a balance.







