How to Understand the Overcharge Phenomenon of Lithium Battery

People tend to have a mistake when charging: it's best to stay fully charged. For OCD, it may kill him to jump from 100 % to 99 % of the battery, but actually keeping the phone in charge is not a recommended behavior, especially after the device is fully charged. Cell phone batteries can't really handle that.

Lithium batteries aren't everything.

Many elders will tell you when you get your first phone that the new phone needs to complete all the discharges, then charge for 12 hours, and then completely discharge. It needs to be repeated three times. At the beginning, you must have done what your elders said, but in fact, smartphones that have already used lithium batteries no longer need such a troublesome battery maintenance process.

It is the nickel-metal hydride battery that needs to perform multiple discharge charging processes. This type of battery has a strong memory. The process of repeated charging and discharge is also to allow nickel-metal hydride batteries to obtain the maximum charging limit. But today's phones use lithium batteries, and there is no need to repeat such a complex battery memory process. So, will the lithium-ion battery always have the highest power limit?

The answer must be no. Although lithium batteries are known for their durability, the inevitable upper limit of their power will be lost during repeated battery recharging. This loss is formed over time, and the cause of loss is in addition to normal charging. Overcharge is the culprit.

How to understand the phenomenon of overloading

Overcharge is actually very understandable, that is, when the phone is still charging the cell phone battery when the battery is full, we say that the phone is overcharged. Continued charging of the battery when the battery is full will lead to changes in the structure of the cathode material, resulting in a loss of capacity, and its separation of oxygen and electrolytes will undergo a violent chemical reaction. The worst result is naturally an explosion.

In real life, there have been many cases of cell phone explosions when charging. For example, Xinhuanet once reported that on March 4, 2015, a 23-year-old girl was charred with a video phone, and the Shanxi Evening News also reported that on June 15, 2015, an 18-year-old teenager was electrocuted when he charged a video phone. The cause of these tragedies can be attributed to the damage to the battery itself, the lack of IC protection for the charger, and the quality of the power supply itself. When the current is still input after the charging is completed, because the battery's capacity has reached the upper limit, most of the current is converted from electrical energy to thermal energy, and the battery begins to heat up.

Common sense also tells us that the best way to store batteries is at room temperature and dry, whether nickel-metal hydride batteries or lithium batteries are actually the same. When overcharging occurs, there is no doubt that the heat energy converted by the current will be emitted in large quantities, which will cause the lithium battery to react with the positive electrolyte, consume the maximum capacity of the lithium battery, and when the heat is accumulated to a certain extent, the fire and explosion events are all possible. happen.

Natural handset makers and chargers will not sit idly by when security is so low. After all, when users have security problems, they must be unlucky, so there is a lot of attention when charging the phone, especially with the mainstream USB port charging mobile phones and chargers are very particular.

They're really good to keep from overcharging.

In fact, most mobile phones now have IC protection. The charger itself will also monitor the voltage and current. In order to protect the safety of batteries and users, trickle-down charging is often used on mobile devices.

When charging with the USB port, if the loss on the wire is not calculated, the USB charging port will negotiate with the mobile phone to charge and match the appropriate current, which will ensure that the mobile phone will not lose most of the current due to the high current input. The battery power is low, such as about 10 %.

At this time, the efficiency of charging the battery is the highest, and the current also reaches the highest state. With the increase in capacity, the current required by the mobile phone will gradually decrease. When the last 10 % to 20 % reach the full power, even the mobile phone will request a pulse small current to charge, so as to achieve the purpose of protecting the battery. This charging method, also known as trickle-down charging, is the current charging plan for mainstream mobile phones to reduce the loss of the upper limit of the capacity and extend the battery life.

In addition to the overcharge protection provided by mobile phone batteries, there is also a way to rely on charging sockets to prevent overcharge. The socket must provide a stable voltage to prevent overcharging. The larger the voltage fluctuation, the current will also be affected. Especially in China, the time voltage fluctuates frequently at night, and it is very important to ensure the stability of USB output voltage. In general, the voltage of the USB charging port is 5V. Some USB charging ports that can intelligently distribute current will slightly reduce the voltage of the charging port when the mobile phone battery is close to full power to reduce the input current to relieve the battery pressure.

These methods have a good inhibitory effect on the overcharging of mobile phones, but it is only because we did not unplug the power supply when the mobile phone completed charging, allowing the mobile phone to repeatedly discharge and recharge the process, resulting in a reduction in the upper limit of the phone capacity.

Overcharging is not a small matter.

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It is not a small matter for ordinary mobile phone users to overcharge. The life of the cell phone battery directly affects the time you use this phone. If you allow the phone to overcharge, you believe that the battery will die in less than a year.

If you can see that the back of the battery has been slightly bulged, it may be a mistake. To say the big, overcharge even directly affects your safety, those poor batteries in the cottage can not be guaranteed to release fireworks or so. If you want to avoid overcharging at all, it seems that you must start with time control.

The page contains the contents of the machine translation.