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Two things you must know about cell phone batteries

Two things you must know about cell phone batteries

Jul 8,2022

    I believe you have also heard this statement: "A newly bought mobile phone must be fully charged for more than 8 hours and repeated several times to fully charge and discharge. This process is called activation, which can make the battery of the mobile phone reach its maximum capacity." What is the real situation? 

    There are indeed some rechargeable batteries that require similar "activation" work. This is the earlier nickel-cadmium rechargeable battery and nickel-metal hydride rechargeable battery. These batteries will produce a phenomenon known as the "memory effect". Charging in an incompletely discharged state will easily overcharge the battery. Over time, crystals will grow on the electrode plates, blocking the contact between the electrolyte and the electrode plates. , causing the voltage of the battery to drop, making the user feel that the battery will be used up soon.

    However, most of the batteries used in our mobile phones and laptops are lithium-ion batteries. Although lithium-ion batteries are small in size, they can store large amounts of energy, so they are more and more widely used. Lithium-ion batteries do not need to be activated by deep charging and discharging at the beginning of use, because the initialization and testing process of the battery is already completed when the battery is manufactured. Lithium-ion batteries also have no so-called "memory effect" and can be recharged at any time. The statement that a full charge and discharge of a lithium-ion battery is recommended on a regular basis is only for the purpose of calibrating the charge detection devices on laptops and some high-end smartphones, not for the benefit of the battery itself.

    But you may find that this is also written in some mobile phone manuals. In fact, the battery of the mobile phone is generally not manufactured by the manufacturer of the mobile phone. This kind of writing on the manual may be to remind the user to test whether there is any problem with the battery. In addition, since nickel-cadmium batteries and nickel-hydrogen batteries do need to be activated, this kind of writing on the manual may also be caused by copying the template.

-Reducing the number of recharges can extend battery life?

    Generally, the life of lithium-ion batteries can reach hundreds of charge-discharge cycles, and such expressions are often seen in the instructions of batteries and equipment. 1 charge-discharge cycle here refers to the process of using up the battery and then recharging it, rather than plugging in the charger and unplugging it once. Continuous deep charging and discharging of lithium-ion batteries has an impact on its life. The above-mentioned data of hundreds of times are also measured under such conditions. However, under daily shallow charge and discharge conditions, the life of lithium-ion batteries is actually quite long.

    In addition, lithium-ion batteries will naturally lose their capacity when they are not used. The main influencing factors are voltage and temperature. Studies have shown that when lithium-ion batteries are stored for a long time in a fully charged state, there will be a significant loss of capacity. The higher the temperature, the faster the lithium-ion battery loses its capacity, and this loss is irreversible, that is, the battery's capacity is permanently reduced. At 0 degrees Celsius, a lithium-ion battery with 40% remaining capacity will lose 2% of its capacity after one year of storage; at 40 degrees Celsius, a fully charged lithium-ion battery will lose up to 35% of its capacity after one year of storage. 

    So what is the correct way to do it? First of all, frequent shallow charging and discharging is more helpful to prolong the battery life than deep charging and discharging. Don't think that the battery will be damaged by charging too many times. This statement does not apply to lithium-ion batteries. So, a good habit is to plug it in and charge it when you get the chance, and then unplug it when it's almost fully charged -- eat small, frequent meals, but don't overeat. Second, the time for the battery to be fully charged should be minimized. Do not unplug the power supply after fully charged, the battery will remain fully charged, although it will not explode, but it will speed up the loss of battery capacity.