Many people are afraid of lithium batteries, but they are helpless. The frustration is because mobile phones, laptops, tablets, and other devices use it, and the fear is because I don’t know when the lithium battery will suddenly make a terrorist attack in front of me: either burning or exploding. Among such incidents, it is naturally related to the electrical characteristics and quality of the lithium battery itself, but it is not ruled out that whether the lithium battery is used correctly is also one of the reasons for the lithium battery accident.
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Lithium battery accidents in the correct use of lithium batteries
The method is based on the characteristics of the lithium battery itself. Therefore, we first analyze why lithium batteries explode or burn from the perspective of electricity. Combustion or explosion usually occurs because heat is accumulated and cannot be diffused, and it accumulates to the point of fire, or if heat accumulates to a certain degree in a certain space, it will happen. As a battery, in the final analysis, the above-mentioned situation usually does not have the following four reasons.
1、 Internal short circuit (mostly soft package large monomer): structure or process defects lead to the insertion of the tabs, the surplus of the diaphragm is too small, burrs, and the diaphragm is discounted. Interpolation of tabs often occurs in thick batteries and internal parallel structures. Insulation of tabs is not in place. Adding a protective plate to the subsequent finished product or using the process will easily cause an internal acute short circuit and cause combustion or explosion (internal short circuit: this is personally I have a deep understanding. At that time, more than 2K batteries of this kind were scrapped, which was actually a design defect-the essence of the abnormality is: an internal acute short circuit), but now this situation is almost rare, unless external factors are involved.
2、 External short circuit: The explosion after combustion caused by the external short circuit of the battery below 1AH is rare. It is usually caused by bulging or simply burning the tabs. Personal analysis has been caused by the external short circuit of power batteries or large-capacity mobile phone batteries. This involves improper use by the customer-the tab insulation is not considered when the metal outer box is installed, and abnormal smoke and combustion of the battery occur at the installation site; the power battery is also often structurally fixed inadequately (not considered properly), and the battery pack is used during the user's use. Shaking can cause damage to the battery's external insulating protective film or damage to the connecting wire, which will eventually lead to short-circuit burning.
3、Overcharge explosion: This is the most dangerous, and it is also the most afraid of the company, but it still happens occasionally. From what we know, there are two points: a. The user does not use the matching charger as required, thereby destroying the protection circuit and the user often charges for an unlimited time. In this case, it is difficult not to explode; b. Unreasonable and the protection board fails, in this case it will be a mess... the same is true for single-cell batteries.
4、The material of the battery itself is not good enough. If the material does not pass, it may overheat under the calibrated voltage and current, which may cause an accident.
Based on the above analysis, if you can use lithium batteries correctly and avoid the above situations as much as possible, you can sort out some methods.：
1、Frequent deep charging and discharging: Lithium batteries have almost no memory. When using lithium batteries or lithium-ion digital products, many friends like to use up the power (protected by the protection board) and then recharge them. In the eyes of many people, this It is also a way of activating the battery. In the use of lithium batteries, we call the state of recharging after running out of power as deep charging and discharging.
In fact, deep charge and discharge is a major misunderstanding of many people when using lithium batteries. Scientists have concluded through experiments that the number of deep charge and discharge is directly proportional to the battery life under other environmental conditions. Multiple charge and discharge Will cause the battery life to end prematurely. Lithium batteries with a long service life can easily cause battery swelling, which can cause an explosion.
2、Overcharge and discharge and excessive charging and discharging current: This situation often occurs when the protection board is not properly designed and charging. We often like to charge the device for a while after the device is fully charged, so that our device can resist It takes longer, but what many people don’t know is that long-term overcharging and overdischarging will cause serious damage and damage to the performance of lithium batteries, and extreme conditions such as explosions will occur. So the battery is fully charged. Well, if you keep plugging in the charger, it will lead to tragedy sooner or later.
3、When charging and discharging, the current of the charger and the general current load of the electrical appliance must be within the specified range. Excessive current load can easily cause the internal short circuit of the battery, thereby destroying the lithium ion and causing potential safety hazards in the circuit. The same is true for the voltage of a rechargeable charger. So when we use the charger, we should also pay attention to see if the charger is qualified.
4、working environment. Lithium batteries are extremely sensitive to temperature. If used for a long time below the freezing point, it may have a great impact and harm on battery life. Long-term exposure to an overheated environment will greatly reduce the life of the battery. In severe cases, the internal pressure will increase and cause an explosion. Even if there is no explosion, the battery will quickly be scrapped in high heat. I feel that in some cases, it is unfortunate because of the explosion of the pool Most of the fatalities were caused by the high temperature of the working environment.
After experiencing many accidents, the manufacturers finally took action. At present, most manufacturers have added protection devices, especially electronic and digital products, which have added double protection or multiple protection, so as to avoid this situation as much as possible. , The enhancement of users’ self-awareness is still very important.
The correct use of lithium battery mobile phone lithium battery
Although lithium batteries are widely used, they are used in automobiles, electric vehicles, mobile phones, tablets, notebooks and other devices. In the near future, there may be more devices to use it, but for now, mobile phones and tablets are used. The device is still the closest lithium battery powered device to us. Therefore, it is necessary to make special instructions for mobile phone lithium batteries.
1 How to charge
In the use of lithium batteries, it should be noted that the battery will enter a sleep state after being placed for a period of time. At this time, the capacity is lower than the normal value, and the use time is also shortened. But the lithium battery is easy to activate, as long as 3-5 normal charge and discharge cycles can activate the battery and restore normal capacity. Due to the characteristics of the lithium battery itself, it is determined that it has almost no memory effect. Therefore, the new lithium battery in the user's mobile phone does not require special methods and equipment during the activation process. Not only is this true in theory, but from my own practice, it is best to use the standard method of charging from the beginning, which is the "natural activation" method. Regarding the issue of "activation" of lithium batteries, many claims are: the charging time must be more than 12 hours, repeated three times in order to activate the battery. This statement of "charging for more than 12 hours in the first three charges" is obviously a continuation of the statement from nickel batteries (such as nickel-cadmium and nickel-metal hydride). So this statement can be said to be misinformation at the beginning. The charging and discharging characteristics of lithium batteries and nickel batteries are very different, and I can tell you very clearly that all the serious official technical materials I have consulted emphasize that overcharge and overdischarge will affect lithium batteries, especially liquid lithium. Ion batteries cause great damage. Therefore, it is best to charge according to the standard time and standard method, especially not to charge more than 12 hours. Generally, the charging method described in the manual of the mobile phone is the standard charging method suitable for the mobile phone.
In addition, lithium battery mobile phones or chargers will automatically stop charging after the battery is fully charged, and there is no so-called "trickle" charging that lasts for more than 10 hours in nickel battery chargers. In other words, if your lithium battery is fully charged, it is also white charged on the charger. And none of us can guarantee that the characteristics of the battery's charging and discharging protection circuit will never change and the quality will be foolproof, so your battery will be on the verge of danger for a long time. This is another reason why we oppose long charging. In addition, on some mobile phones, after charging for a certain period of time, if the charger is not removed, the system will not stop charging at this time, but will also start a discharge-charge cycle. Perhaps the manufacturer of this approach has its own purpose, but it is clearly detrimental to the life of the battery and mobile phone/charger. At the same time, long-term charging takes a long time and often needs to be carried out at night. According to the situation of my country's power grid, the voltage at night in many places is relatively high and fluctuates greatly. As mentioned earlier, lithium batteries are very delicate, and their ability to withstand fluctuations in charging and discharging is much worse than that of nickel batteries, so this brings additional dangers. In addition, another aspect that cannot be ignored is that lithium batteries are also not suitable for overdischarge, and overdischarge is also very detrimental to lithium batteries. This leads to the following question.
2 When should charging start in normal use
On our forums, you can often see this statement, because the number of charging and discharging is limited, so the battery of the mobile phone should be used up as much as possible to recharge. But I found an experiment table on the charge and discharge cycle of lithium-ion batteries. The data on the cycle life are listed as follows：
Cycle life (10%DOD)：>1000 times
Cycle life (100%DOD)：>200 times
Among them, DOD is the abbreviation of Depth of Discharge. It can be seen from the table that the number of rechargeable times is related to the depth of discharge, and the cycle life at 10% DOD is much longer than that at 100% DOD. Of course, if it is converted to the relative total capacity of actual charging: 10%*1000=100, 100%*200=200, the latter's full charge and discharge is still better, but the previous netizen's statement needs to be corrected: in normal In this case, you should reserve the battery according to the principle of recharging when the remaining battery power is used up, but if your battery is not likely to last the entire day on the second day, you should start charging in time. Of course, if you are willing to carry it back It's another matter of bringing the charger to the office. And you need to charge to cope with the upcoming important events that are expected to cause busy communication, even when the battery has a lot of remaining power, then you only need to charge in advance, because you have not really lost the "1" charge cycle life. , Which is just "0.x" times, and often this x will be very small. The principle of recharging the remaining battery power is not to make you go to extremes. Like long-term charging, a widely circulated saying is "try to use up the battery of the mobile phone as much as possible, and it is best to use automatic shutdown." This approach is actually only the approach on nickel batteries, the purpose is to avoid the memory effect, unfortunately, it is also spread today on lithium batteries. There was an example where someone continued to use the phone without charging after a warning that the battery level of the mobile phone was too low, until it was automatically shut down. As a result, the mobile phone in this example did not respond during subsequent charging and booting, and had to be sent to customer service for overhaul. This is actually caused by the battery's low voltage due to over-discharge, so that it does not have normal charging and starting conditions.
3 Important tips for the correct use of lithium battery mobile phones
In the final analysis, my most important reminder about the charging and discharging problems of lithium battery mobile phones in use is：
1、Charge according to the standard time and procedure, even if it is the first three times;
2、When the phone battery is too low prompt, you should try to start charging as soon as possible;
3、The activation of the lithium battery does not require a special method, and the lithium battery will be naturally activated during the normal use of the mobile phone. If you insist on using the popular "first three 12-hour long charge activation" method, it won't actually work. Therefore, all pursuits of 12-hour long charging and automatic shutdown of mobile phones with lithium batteries are wrong. If you did something wrong in the past, please correct it in time, maybe it's not too late. Of course, when the quality of the protection and control circuits of the mobile phone and the charger are good, the protection of the lithium battery is still quite guaranteed. Therefore, the understanding of the charging rules is the key point. In some cases, some concessions can be made. For example, if you find that your mobile phone must be charged before going to bed at night, you can also start charging before going to bed. The key to the problem is that you should know what the correct approach is and don’t deliberately follow the wrong statement.
Battery maintenance for the correct use of lithium batteries
In fact, the battery does not have too much attention to use, in other words, it is not very useful to take into account. How many times a battery can be used, the difference is more due to individual differences in the manufacture of the battery itself, rather than the method of use. In addition to its own battery quality, the battery's own service life is limited. Once the battery is off the production line, its lifespan begins to elapse. Regardless of whether you use it or not, the service life of lithium batteries is only two to three years. One of the important reasons for the decrease in battery capacity is the increase in internal resistance caused by oxidation. Finally, the resistance of the electrolytic cell will reach a certain point. Although the battery is fully charged at this time, the battery cannot release the stored power. Many friends think that the first use of lithium batteries should be charged for more than 16 hours, so that the battery can be fully activated, in fact, there is no basis for doing so. This is just the popular method of charging nickel-metal hydride or nickel-cadmium batteries. Not applicable. Because this kind of lithium polymer-based battery does not theoretically have a memory effect, even if it does, it is completely negligible. So it only takes about 3 hours to charge it. If it shows that the charging has been completed and the external power supply is not needed for the time being, then you can unplug the power supply without waiting such a long time.
In fact, battery maintenance has always been a hot topic for notebook computer users, and in the battery section of major notebook forums, this topic has already formed a consensus. But in fact, there are many misunderstandings. In the final analysis, it comes from two aspects. One is that "thinking has not kept up with the transition from nickel-metal hydride batteries to lithium batteries." The other is even more funny and comes from mobile phones, because mobile phones are actually most users. The first thing I came into contact with was a device that used rechargeable batteries, so I would take it for granted to extend some of the mobile phone habits to the PSP. I don't have the ability to train most PSP users to become experts, and there is no need for that. There is no absolute truth in the world. I will not vowed to say that my theory must be correct like some friends who are theoretically supreme, and I want everyone to be convinced by him. I just will be in the major notebook forums and the electrical industry. The opinions generally agreed by senior engineers will be shared with you. After all, PSP is a consumable, no matter how hard you work, the battery life is only 2 to 3 years. If you feel that in order to bring the so-called maintenance method to the PSP battery that is negligible to almost ineffective, you are willing to make up the full charge and discharge time and often interrupt the game and wait for the charge, then you don't need to continue reading.
Below I will clarify some of the most easy to fall into the misunderstanding, and give the views and practices that I think are correct.
Misunderstanding 1: The PSP needs to be repeatedly charged and discharged three times to activate the battery. Unless the PSP you bought is a product that has been in stock for more than one year, you don’t need to do this, because the current battery cells have been activated when they leave the factory, and the cells have been packaged into a PSP battery. The activation test, so the battery you get has already been activated, and doing three more charge-discharge processes is just a needless increase in battery loss.
Misunderstanding 2: The first charge must be sufficient for 12 hours. This is suitable for the early nickel-metal hydride battery equipment without battery control circuit, but it is a joke for the PSP with intelligent charge and discharge control module nowadays. When the PSP battery is fully charged, the charging current will be automatically cut off. The system displays as "external power supply". Even if you continue to charge for 120 hours, there will be no change in the state. Generally speaking, it is fully charged in 3 hours, and the remaining "charging" is just a waste of your own time. Instead, when you get a new machine, you should discharge the battery before charging.
Misunderstanding 3: The battery needs to be fully charged and discharged once a month. For nickel-metal hydride batteries with strong memory effect, this is a necessary work, but for lithium batteries, this cycle is too frequent. Lithium batteries theoretically eliminate the memory effect. Even if there is, it has been greatly weakened and can be ignored. If you use the battery frequently, then you should discharge the battery to a relatively low level (about 10~15%) and then recharge it, but if it is discharged to the point where even the machine can’t be turned on (0~1%), it belongs to the lithium battery For deep discharge with greater damage, it is generally sufficient to do this operation once every 2 months. If you rarely use batteries, you can do this once every 3 months.
Misunderstanding 4: Working while charging or continuing to use an external power source after charging will damage the host and battery. This is the most ridiculous argument. How much response can the so-called theoretical arguments on the mechanism of hole electrons, subcharges, etc. get in practice? First of all, the opinions of the battery industry academia are not unified. The theory is still different. How to use it to guide the actual use of consumers? The loss of the battery is divided into normal loss and harmful loss. The degree of loss caused by external power supply and charging while using is completely within the normal loss range of the battery. That is to say, no matter how systematic and theoretical maintenance measures are taken, the battery will age. This is like how amazing cosmetics and maintenance can not prevent beautiful women from becoming old women, at most it only delays it, but the cosmetics on the surface play a role. How much real utility can be, this is by no means the theory can explain-respect for actual use experience is the correct and scientific view of knowledge. Some people may say that the only way to avoid battery aging is not to use it (so many people choose to take the battery off), but this makes the PSP portability meaningless. Secondly, even if the battery is in a sealed state, it will be over time. Prolonged and naturally aged. Batteries are actually a semi-consumable product. As long as the batteries bring you enough convenience and happiness, I think their sacrifices are valuable.
There are misunderstandings, naturally, it is also because there are corresponding generally agreed views on battery maintenance and usage methods, which are listed as follows:
1.Avoid complete discharge (use to black screen and power off)
2.Frequent charging and discharging of the lithium battery, charging or using an external power supply when it is not exhausted, using while charging, or continuing to use an external connection after charging is completed, will not cause additional loss to the battery.
3.When not in use for a long time, the lithium battery should be taken out and placed in a cool and dry place. Do not freeze to avoid water erosion. Avoid using it in a high-temperature car. If stored for a long time, charge the battery to 40% and place it
4. As a notebook user, if you use a fixed power supply most of the time, you can remove the battery and place it in a cool place, but this is only for the improvement of environmental factors such as temperature and humidity of the battery. As a PSP, using an external power supply with a battery installed will not cause additional damage to the battery. And out of the concept of portability and protection of the battery cover and metal contacts, it is recommended not to frequently remove the battery because of the use of an external power supply.
5. Avoid purchasing spare lithium batteries for storage, because even if the battery is not used, its service life is naturally damaged. Therefore, the maximum use of the battery within the limited life time of the battery reflects the value of the battery, rather than using various kinds of failures. Realistic theories to torture yourself and PSP for entertainment.
The above is the general consensus obtained by consulting senior members, professional owners and many electronic and electrical engineers in the industry in major electrical professional forums. I hope that it will be used as a reference for everyone.
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