Lithium battery applications in life suddenly expanded, mainly due to smart phones, widespread use of wearable devices, electric bikes and new energy vehicles, all these years tips on how to use the battery, lithium battery explosion news constantly, but Often contains a lot of misleading information. In this article we talk about the simple application of lithium batteries to complex applications.
To measure battery performance, there are several important indicators:
First, charge and discharge rate: the higher the better
"C" is a special symbol that describes the magnitude of the battery charge and discharge current. The 1C discharge represents the amount of current that can be placed from full charge to empty within 1 hour. The iPhone 6 battery capacity is 1810mAH, then the 1C discharge current of this battery is 1.81 amps; the battery capacity of each battery used in the BYD e6 electric car is 200AH, then the battery 1C discharge current is 200 amps. If a battery is discharged at a high rate, it usually emits less energy than a low rate.
Electricity discharged at different discharge rates
From the test results in the above figure, it can be seen that the energy discharged from the 10C discharge of this power battery is 85% under 1C discharge, and the energy released by discharge at 20C is only 70% under 1C discharge.
Second, the number of charge and discharge cycles: the more the better
500 times is a common value of lithium batteries, and the number of charge and discharge of lithium batteries made according to different materials ranges from 300 to 3000 times. The specific meaning of this value may be slightly different for each factory, which can be roughly understood as: the charge and discharge rate specified by the manufacturer (such as 1C discharge, 0.3C charge; each time from 0% charge to 100%, according to this cycle) After 500 cycles, the battery capacity is still 80%. The relationship between the number of charge and discharge cycles and usage habits is too great, let's take a few examples.
1. The effect of charge and discharge intensity on the number of cycles
Factory labeling: every time from 0% charge to 100%, 1C release, 0.3C charge, 500 times after the capacity decay to 80%, this is the most stringent test cycle, it can not be so strict, see below
If the cycle of electricity is 25%-75%, 1C put, 0.3C charge, after 2000 times the capacity decays to 80%
If the cycle of each power is 50%-100%, 1C put, 0.3 charge, after 1800 times, the capacity is attenuated to 80%.
2. The effect of shallow filling and shallow release on life
Factory labeling: every time from 0% charge to 100%, 1C release, 0.3C charge, 500 times after the capacity decay to 80%, is the most stringent test cycle, can not be so strict, see below
The cycle of each power is 25%-75%, 1C put, 0.3C charge, after 2000 times the capacity decays to 80%
Every time the power cycle is 50%-100%, 1C put, 0.3 charge, after 1800 times the capacity decays to 80%
The above two examples show that the smaller the charge and discharge rate, the more favorable the life is improved; the shallow charge and shallow release is also beneficial to the life improvement.
Third, internal resistance: the smaller the better
This parameter changes with the load and weight, temperature and other factors. As the battery life decreases, the internal resistance also increases. The battery with the lower internal resistance can be charged and discharged at a high rate. The internal resistance of the 18650 battery is about 50mΩ, and the power type 18650 battery is about 15mΩ. I want to know how much internal resistance needs to be measured with special equipment, and ordinary multimeters can't.
Tool for measuring internal resistance of batteries
Fourth, battery consistency
The higher the consistency of the capacity, internal resistance, charge and discharge curves of batteries produced by the same material and the same process, the better. It is critical that the battery can form a battery pack on a large scale. The larger the battery pack, the higher the consistency requirement.
The following pages we will apply the difficulty of the application:
1. Lithium batteries in mobile phones, tablets, and wearable devices
2, lithium battery in laptop and mobile power
3. Lithium battery in electric bicycle
4. Lithium battery in electric vehicles
Introduce some knowledge separately, so that the paging is sorted by the size of the battery from small to large.
I. Lithium batteries in mobile phones, tablets, and wearable devices
Why is this field the easiest? Because there is only one lithium battery in these devices, and they are basically ternary lithium batteries. Ternary means three elements: nickel, cobalt, manganese, and the positive electrode material Li(NiCoMn)O2 of this lithium battery, which is not exactly the same, and will adjust the ratio of the three elements according to the requirements of use.
First, charge and discharge rate
Batteries used in digital devices are usually very low on this item. Is it difficult to use a fully charged mobile phone in an hour to automatically shut down? No one will design a digital device that lasts only one hour. At least 3 hours can be extended, so the discharge rate of the battery reaches 0.3C, which can meet the demand. The charging requirements are often very low. Usually, the digital devices that are full for 3-4 hours can be accepted, so the requirements for the battery are charged. It is also around 0.3C.
Regardless of domestic or imported lithium batteries such as Panasonic and Samsung, 1C discharge is the minimum specification, and the requirements for digital equipment to discharge batteries are far lower than the general standards of the battery industry. The charging rate is roughly equivalent to the basic indicators that the battery industry can currently achieve. If there is no special design, there is no need to worry.
OPPO's battery flash charging characteristics puts high demands on charging
Recently, there have been special cases in the mobile phone industry. The OPPO has been proposed as a representative of fast charging. In fact, it has placed special demands on battery manufacturers. According to OPPO's latest N3, VOOC flash charge promises to be filled with 75% of electricity for 30 minutes. This is 1.5C charging current, which is 10 times of the normal mobile phone battery charging rate, and N3 sells 3999 yuan is also expensive. At least this battery will be one or two times more expensive than a normal battery.
Second, the number of charge and discharge cycles
In digital devices, mobile phones are the most powerful products. We calculate them on a daily basis. The number of cycles is 500 or 500 days. Is this correct? In fact, it is out of the conditions of use, so it is wrong. The 500-cycle cycle refers to a 1C discharge, and a continuous cycle of 500 cycles under 0.3C charge, with the first 80% of battery capacity remaining. However, our usual use of mobile phone discharge rate is much less than 1C, often between 0.01C-0.5C. So the number of cycles can usually be 700 times and 80% of the battery remains. This has been 2 years, and the phone is almost out of date. Apple is very smart in this regard. It does not use a large battery, not only can you get the advantage of thin and light, but also because you have to change the next iPhone after 2 years, why do you have to spend more on the battery? ? As for some people who obviously feel that their battery life is less in a year, there is indeed a reason, and then analyze.
It’s not good to keep 100% power at any time.
Other digital devices, such as tablets, have a longer battery life cycle, but sometimes they find that the battery life has dropped significantly in less than two years. This is also explained. You will know the full article.
Third, the battery internal resistance
There is no special explanation.
Fourth, battery consistency
There is no special explanation.
II. Lithium batteries in laptops and mobile power
What are the meanings of the 4-cell, 6-core, and 8-core notebook battery specifications? This refers to the number of 18650 batteries, with 8 cores as an example, there are 2 combinations, one is 2 strings and 4, and the other is 4 strings and 2, which one is based on the notebook manufacturer's voltage conversion circuit. Design, and battery compartment shape.
4-cell laptop battery
This statement can also describe the mobile power supply. The commercially available 10400mAh capacity of the mobile power supply is a parallel connection of 4 2600mAh 18650 batteries. In order to seize the Chinese market, Samsung SDK takes a low price for large orders, and even sells one dollar/piece. Therefore, many big-name mobile power manufacturers like to use this kind of battery with low quality and good quality, and because the single capacity is 2600, so the capacity of mobile power is often a multiple of 2600mAh: 5200mAh, 7800mAh, 10400mAh.
First, charge and discharge rate
The new laptop battery has less than one hour of photoelectric output, so the discharge rate of 1C is enough for them, the charging requirements are not high, such as laptop batteries filled in 3-4 hours, everyone can accept. For mobile power, the battery charge and discharge rate is even lower, which is the lowest among all digital devices.
Xiaomi 10400 mobile power internal structure
In the current market of 10400mAh (3.7V) mobile power supply, the maximum output current is 2A (5V), that is, it takes 3.7 hours to discharge the photoelectric with the maximum current. The discharge rate is sufficient as long as it meets 0.3C. For charging, the usual specification is 10400mAh with a 1.0A input. The charging rate is only 0.13C. This is why mobile power inferior products are particularly high: even regular manufacturers can buy the lowest performance in the battery market (note that low performance and poor quality are not exactly the same, but still highly relevant) products used in mobile power Medium, but also to meet the needs of the use of specifications.
Second, the number of charge and discharge cycles
The frequency of use of notebooks and mobile power is significantly lower than that of mobile phones. The mobile phone charges up to three days at a time. However, mobile power and notebooks often do not charge and discharge once a week, so as long as 50 times of charge and discharge life is guaranteed. Can support for one year. For mature lithium battery is the worst the worst can also provide life cycle 300 times, the number of people using laptops and mobile power supplies are enough for normal use of the 6-year.
And we often use it for less than a long time to upgrade, so especially in the mobile power industry, the actual use of light load and low frequency charge and discharge times, it is difficult to detect the quality of the product. Some unscrupulous manufacturers will use the worst batteries and even use the disassembled electromechanical cores on mobile power. The dismantled electromechanical core may have been used in other equipments before, and it has been cycled 400 times. It will be eliminated 100 times according to the life expectancy, and 100 times is enough for the mobile power supply to last for two years, so the waste is bought and loaded. There is no one in the mobile power supply.
Relative to mobile power, the original battery cells in the notebook are from international manufacturers. But we also often find that some people around the notebook bought less than 2 years of battery life has dropped significantly, what is the reason?
I still remember that the previous page said that the tablet life cycle is not frequent, but some will also appear 1-2 years, the battery life will drop significantly? In fact, they are caused by the same cause: the battery is not properly stored.
If you are fully charged with the battery, or if the charging cable is plugged into the device, you can maintain the maximum power at any time and the battery capacity will decrease rapidly. This reason relates to the structure of the lithium battery.
Lithium battery internal sketch
The positive electrode of a lithium battery is composed of a metal oxide containing lithium ions, and the negative electrode is generally a crystal lattice composed of graphite. When charging, lithium ions move toward one end of the graphite, and finally penetrate into a stable crystal lattice composed of graphite, and the potential is ready to be developed. . The more lattices that can hold lithium ions, the more lithium ions that can be moved, and the larger the battery capacity. The main effect of long-term full-scale storage is the amount of lithium ions that can be moved. Since the battery reaches 4.2V after full charge, the high voltage is maintained to cause some reaction between the electrolyte and the positive and negative electrodes of the battery, and these reactions are at 3.0V- Although it is happening in the state of 3.7V, it is very weak. This reaction produces a passivation film on the electrode. The higher the voltage, the thicker the film, and the thicker the film, the less the amount of lithium ions that can be moved into the graphite lattice of the negative electrode. So the macro performance is the battery capacity attenuation.
"small house" composed of negative graphite for lithium ion drilling and drilling
What counts as "long-term"? In my opinion, 7 days is enough to cause bad effects. How bad is it? Here is an example. The people who play the model have two new ternary materials, lithium batteries A and B, which are the same size. They are bought in June and stored at the same time. The remaining power of A is 30%, B is 100%, 3 months later. The battery capacity was tested, the A capacity was the first 98%, and the B capacity was the first 60%. That's right, the impact is so bad, so your laptop battery often maintains a high voltage for a long time, so it's not unusual to drop a year's follow-up. Mobile phones are the least prone to long-term full-charge storage, because even if they are full, they are always in use, and the voltage drops in less than a few hours. However, the mobile phone occasionally encounters this problem, such as shutting down after being fully charged. At this time, there is no power consumption, and the battery has been maintained at a high voltage. Maybe after a week, when you open the box, the battery has been bulged.
The correct way is to charge 30%-40% of the electricity, and then save it for a long time.
Third, the battery internal resistance
There is no special explanation.
Fourth, battery consistency
The barrel effect is about how much water a barrel can hold depends on the height of the shortest piece of wood in the wall. It is better to put it on the lithium battery to describe consistency. Poor battery consistency performance has a greater impact on batteries with more parallel groups.
Notebook 6-cell battery schematic
Assume that the third 18650 of the 6-cell battery in the figure has a faster capacity drop for some reason, and soon the capacity is only 75%. The six of them are connected in parallel, so the third battery will be discharged during the discharge. The discharge termination voltage is reached at the earliest, so the battery pack discharge will stop regardless of whether there are no other 5 batteries. The same is true when charging. As a result, the other five batteries did not have any problems, and they were also charged and discharged synchronously with the problematic 18650. This group of batteries was severely attenuated from the outside. In fact, there is only one problem in it. This is the embodiment of the importance of battery consistency.
III. Lithium battery in electric bicycle
Brands such as Luyuan and Xinri have entered every household since 2010, but most of the electric vehicles used were lead-acid batteries. From 2012 began to appear after the lithium battery of the electric bicycle, the common voltage specification is 36V-48V, capacity 8Ah-12Ah. The electric bicycle with the pedals uses a 48V12Ah lithium battery and has a pure electric life of 50 kilometers.
First, charge and discharge rate
There is no special requirement for charging bicycles. The common charging rate is between 0.1C and 0.3C. The battery factory can easily reach the standard, but the discharge rate is slightly higher, at least 1C. This is not a big pressure for the battery factory. But there is also an electric motorcycle that uses the shape of a scooter and can even exceed 100km/h. The battery requirements for this car are increased to 2C-3C, so if you assemble this high-performance electric car yourself, Calculate when purchasing a battery.
Lithium battery at the arrow
Manufacturers of batteries often do not have to worry about their own batteries generally have three types: lithium iron phosphate battery, three yuan lithium battery, power three yuan battery. Their highest discharge rates are: 2C, 1.5C, 10C. You can also increase the current corresponding to the 1C discharge by increasing the capacity of the battery pack.
Second, the number of charge and discharge cycles
The lithium iron phosphate battery has a life of about 2,000 times, a ternary lithium battery of about 800 times, and a power ternary lithium battery of about 800 times. However, since the electric bicycle is often not a single battery, the barrel effect causes the first capacity failure after the group, and the time is advanced, which is about 1/4 to 1/2 of the single life cycle.
Of course, this is also related to usage habits. All the rules just mentioned are applicable here, because we are here to talk about another positive electrode material: lithium iron phosphate, so just say it.
Modified lithium iron phosphate battery pack used in electric motorcycle
The energy density of lithium iron phosphate is 40% lower than that of ternary lithium battery. The lithium iron phosphate battery of the same energy is bulky and heavy, and the advantage lies in the number of cycles and good maintenance. For example, the condition just mentioned is that the ternary lithium battery is fully charged for 3 months, and the battery capacity is reduced to 60% of the initial capacity. However, lithium iron phosphate can maintain 90% of such severe storage conditions, although it is lost, but it is lost. Far less serious than the ternary lithium battery.
For this reason, most of the energy (85% or more) of lithium iron phosphate is concentrated on the voltage of 3.2V. Although the cutoff voltage of this battery is 3.6V, the energy stored in the range from 3.6V to 3.2V is not yet To 1% of the total energy, even after being filled, the voltage will drop back to 3.2V after a few minutes of standing. Therefore, lithium iron phosphate automatically maintains low voltage stress. It is not easy to form a passivation film.
Third, the battery internal resistance
There is no special explanation.
Fourth, battery consistency
The issue of consistency is even more important. At present, there are roughly two types of single cells used in electric bicycles:
1. Small single battery, that is, 18650 battery, capacity 2.2Ah-2.6Ah, the number of batteries in each group is 200-500.
Use a small monomer to form a battery pack, to set up a 120V100Ah battery pack
2, large single cell, the capacity is generally between 20Ah-40Ah, the number of cells in each group is 15-30.
Let's take the 72V40Ah battery pack as an example. If you use a small single cell, you need 20 strings of 19 and a total of 380 18650 batteries. Every 20 heads and tails are connected to one. 19 battery packs require a voltage difference of 0.02V or less at any time. It sounds very demanding, but it is actually not as difficult as imagined, because the process of 18650 battery has been Very mature, the consistency of the same batch of batteries is quite good.
Large monomer lithium iron phosphate battery, various specifications
If you use a 20Ah large single cell, you need 20 series 2 and a total of 40 large single cells. As long as the 40 pieces work together, there is no problem. In general, the large single cells are consistent after being grouped. The chance of a problem is even smaller. There are also unfavorable factors. If it is a large single-cell battery of lithium iron phosphate, the consistency will be much worse than that of the ternary lithium battery. Therefore, the battery pack needs to add an automatic equalization circuit to determine which battery needs at the end of each charge. Charge the battery for a while to solve the weakness of poor consistency of lithium iron phosphate.
The issue of consistency has risen to a very important position here, but it has not yet reached its limit.
IV. Lithium battery in electric vehicles
Lithium batteries in electric vehicles are the most complicated applications, because the batteries face high-power charging and discharging, large-capacity storage, high-frequency use, long-term driving, etc., the batteries used are regular large-scale high-standard products, eliminated in electric vehicles. The used batteries are often used to install electric bicycles. They are still used (of course, this is a profiteer's behavior). The usual practice is to eliminate the energy storage power station for storing wind energy and solar energy.
First, charge and discharge rate
According to different cars, the difference is very big. The well-known BYD Qin used 152 lithium iron phosphate batteries with a monomer capacity of 26Ah. The total voltage of the discharge voltage curve is 10.5KWh, and the maximum power of Qin's motor is 110KW. A discharge rate of 10 C is required. BYD's other pure electric car e6 battery has the largest battery capacity of the current passenger car: 63KWh, so to achieve higher power does not require a high battery discharge rate, the discharge rate of the e6 battery is 1.5C. The bus with the largest battery capacity of pure electric vehicles, such as BYD's 13.8-meter electric bus K9, has a battery capacity of 324 KWh. Due to the huge battery capacity, the battery discharge rate only needs 0.5C for the power of 180 KW.
BYD K9 electric bus sold to Israel
There are also some non-plug-in hybrid cars, the battery capacity is only 1.5KWh, but the maximum power of the motor reaches 30KW, the battery discharge rate used in these cars may have 20C, which is compared with the mobile power application scenario 0.2C It is more than 100 times bigger.
Camry hybrid version, you need to use a power battery, the discharge rate is higher
Pure electric vehicles are mostly equipped with two charging modes: fast charging and slow charging. The fast charging is full for 2 hours, so the charging rate is 0.5C. There is even more exaggeration. For example, Tesla 's boss, Musk, hopes that the next generation Tesla's charging time can be reduced to 10 minutes, so that the charging rate will be at least 6C.
Second, the number of charge and discharge cycles
When designing a new energy vehicle, the battery life is longer than the life of the vehicle. Therefore, the battery life is at least guaranteed to be 300,000 kilometers, and most of the pure electric and hybrid cars that have been released have no problem. In terms of BYD e6, pure electric battery life is 300 kilometers, battery capacity is 63KWh, calculated according to 2000 cycle life, which is 600,000 kilometers (actually slightly less than 600,000 kilometers, think about why?) This is far more than the average owner The total mileage requirement.
BYD e6 taxi driver
E6 with a total mileage of more than 500,000 kilometers
In the actual test, BYD has operated 850 e6 taxis in Shenzhen since 2010. Up to now, there have been dozens of vehicles with a total mileage of more than 500,000 kilometers. In July, I went to Shenzhen to investigate e6 pure electric taxis. They are a group of batteries that have been used from the factory until now. Fortunately, they have met a driver with a total mileage of 500,000 kilometers. He is honored by the reputation. Not only has he not changed his battery, but his battery life has not dropped significantly. Coincidentally, the car home. I have tested the battery life of this driver car. In the case of urban + high speed + full air conditioning, I ran for 260 kilometers.
BYD pure electric car e6
At present, new energy vehicles, especially pure electric vehicles, except for BYD, which leads the industry for 5-7 years, the products released by other self-owned brand vehicles are developed after receiving the notice of the central government to develop new energy four years ago. They are all fuel truck racks throwing away the engine and fuel tank, stuffed into the motor and the battery is modified. The characteristic is that the battery life is 150-180 km under the working conditions (it will definitely reach 150 km, because the national and local subsidies of 150 km are on a step!), and the actual life of these cars is often 120-150 km in summer and 100 in winter. -120 km. Is the number of battery cycles sufficient for these pure electric vehicles with impure purity?
Lithium iron phosphate battery
This depends on the specific situation. If lithium iron phosphate battery is used, then 120 kilometers by 2000 times, there are also 240,000 kilometers of battery life. In addition, because you are not using the throttle every time, and each time it is discharged from 100%. It is normal to 0%, so it is normal to cycle more than 2000, which also ensures that the batteries of these cars can at least last longer than the whole vehicle.
However, another type of pure electric vehicle that uses a ternary lithium battery is a little overhang. Since China's current new energy vehicles use ternary lithium batteries as batteries, no one buys them, and the statistics after long-term use are even more difficult to talk about. . However, there are precedents in foreign countries, and it is a well-known example. Nissan LEAF is the world's largest selling pure electric vehicle. It has sold 130,000 units since its launch in 2011. The large sales volume does not mean quality. Ok, mainly because it is cheap. Since the listing in Europe and America, it has been the lowest price among pure electric vehicles. The price of the US dollar is 180,000 yuan.
NEC modified lithium manganate ternary material 35Ah battery, for morning wind car
The car has experienced a significant decline in battery life after a three-year period of use. This car uses NEC's modified lithium manganate battery (also belongs to the ternary lithium battery category, only the positive material ratio and doping slightly adjusted), soft pack monomer 35Ah. Although Nissan does not necessarily recognize this problem, the disassemble lithium battery sold by Taobao store can explain the problem. In the battery business list of the electric vehicle alliance, regardless of the merchants in Shenzhen, Guangzhou, Wuhan, Changsha, Beijing, Dalian, they all have the same Disassembled electromechanical core: NEC modified lithium manganate 35Ah soft pack large three yuan. Some of these monomers are very new in color, and there are no traces of shear welding on the ear. They actually came from the Nissan Leaf wind electric car. The number of cars that had problems in themselves was too large. After the factory was sold, the control was not strict, so the core of the dismantled electromechanical core was discharged and sold by the merchant to the DIY electric motorcycle.
The root cause of such problems in the wind is that it uses a battery cycle that is much less than lithium iron phosphate. It should be around 800 times. If you are interested, you can search for Baidu. "Learning the battery is aging too fast," or on google. Search for "nissan leaf battery capacity loss" and you will see this problem. Nissan also established an investigation team for this purpose, followed by a battery replacement service, and the replacement price of the entire battery pack was $5,500.
Unfortunately, this car only changed its name and came to China to become the pure electric car "Qinchen-Morning Wind" of Dongfeng. With the new name, each car got 95,000 pieces of state and local subsidies. The car currently has a domestic price of 267,800-28,800.
Nissan Leaf (LEAF) or Dongfeng Morning Wind
Including the morning breeze, all the pure electric vehicles with a working condition of less than 200 kilometers are not worth buying. The mission at the beginning of their birth was originally a higher level of exchange, so as to obtain the qualification for subsequent expansion of the fuel vehicle. In 2010, FAW, BAIC and other car companies did not expect that new energy has become an irreversible strategic direction for automobile development in 2014. It is not a good thing to send a few pure electric vehicles to the national catalogue of new energy vehicles. Even if they have plans to re-develop a model specially designed for electric vehicles, they will wait four years before they go on the market. Do they really have this R&D strength? I personally prefer that after a few years, these car companies still rely on the introduction of joint venture brand models to sell pure electric vehicles developed by others. The operation method can refer to the wind and the morning wind.
BYD Qin
Among all car companies, only BYD is the exception. BYD has been working hard to make electric cars before acquiring Qinchuan Automobile in 2003. Not only do the motor, electric control and battery research and development produce their own hands, but also the source of positive and negative materials: mine They all compete for control. The 49% share holder of the world's second largest spodumene mine is the cousin of BYD Chairman Wang Chuanfu. In addition to this there are a number of shares in the mine. It is no exaggeration to say that whether it is a pure electric car or a plug-in hybrid car, the level of BYD products is at least 5-7 years ahead of other domestic car companies, even if it is worldwide, if only new energy vehicles are discussed, then the motor and electric control The three most important components of the battery, BYD, are also among the best.
For BYD, new energy vehicles are products that are related to the survival of enterprises. For other car companies, new energy vehicles are related to the amount of subsidies. .
Third, the battery internal resistance
There is no special explanation.
Fourth, battery consistency
Since many car companies use lithium iron phosphate batteries, the battery capacity of this battery can reach 200Ah, so don't look at the car battery capacity is huge, the number of monomers is not too much. But there are exceptions, that is Tesla, Model S has another way, using Panasonic 18650NCA battery, a total of 7623, a single section capacity 3.1Ah, 2011 Tesla bought a total of 200 million such batteries, which is only enough to produce Model S high with 26,000 cars.
If the remaining 7622 normal battery cannot successfully use the full 3.1Ah capacity due to a certain battery, the power system of this car will be too failed. Here we see the most extreme application of lithium battery in consistency. . In order to ensure consistency, in addition to rigorous requirements to Panasonic, Tesla also made a costly battery management system for the battery, this system can not only monitor the voltage and current of each battery, to achieve a reasonable Charge and discharge can also guarantee that their temperature is consistent. Whether the battery charge and discharge curve is consistent and the battery temperature has a great relationship, the Tesla chassis is covered with batteries, and the battery temperature varies greatly from position to position. Therefore, in order to ensure the same charge and discharge curve, the temperature of the 7623 battery must be the same. This is achieved by a two-way flow liquid cooling system with 50% water and 50% ethylene glycol.
According to industry experts, Tesla's battery management system, even if it is all produced in China, costs 6000-8000 US dollars. Compared with the electric bicycle battery pack, it has 100-200 dollars of charge and discharge protection board with automatic equalization function. More complicated, after all, the number of batteries to be controlled has risen from four hundred to seven thousand.
Lithium batteries in electric vehicles cost us too much ink because the situation is the most complicated. Let's talk about the common saying of lithium batteries.
VI. Various rumors about lithium batteries (1)
Proverb one: The new battery is bought and charged for three times to activate?
This is a statement copied from nickel-cadmium batteries many years ago. The activation of lithium batteries is carried out in the factory. The raw materials are processed, coated, sliced, rolled, laminated, assembled, and baked. , formation, high current test, even after the completion of the activation. Ordinary people do not have such equipment at home. This kind of suggestion even appeared in the mobile phone manual of a certain brand. Perhaps the person who wrote the manual has been copying the previous version and found no errors.
When you buy a lithium battery, you will find that there is still about 30% of the remaining battery, which is the most ideal remaining battery when the factory is in stock.
Lithium battery activation process, do you have this equipment?
Proverb 2: Lithium battery should be recharged with photoelectric?
This is also the saying from the nickel cadmium 10 years ago, that battery has a memory effect, so it should be recharged after the light is released. Previously we have an example of the effect of charge and discharge percentage on life:
Factory labeling: every time from 0% charge to 100%, 1C put, 0.3C charge, 500 times after the capacity decay to 80%
The cycle of each power is 25%-75%, 1C put, 0.3C charge, after 2000 times the capacity decays to 80%
Every time the power cycle is 50%-100%, 1C put, 0.3 charge, after 1800 times the capacity decays to 80%
The latter two methods use only half of the power at a time, but the number of cycles is four times the previous one, and the previous one is 3.6 times, so the ability to release the whole life is still twice as much as the deep charge. This is the so-called "shallow filling and shallow release is conducive to extending life." 0%-100% belongs to deep charge and is the most costly use. Therefore, the mobile phone battery is used with the charge, do not pursue full power at all times, and do not often use automatic shutdown, which is most beneficial to battery life.
This does not mean that there is no electricity in the battery.
However, it should also be noted that when we use the mobile phone and tablet to automatically shut down, it is not 0% of the battery power. Generally speaking, the mobile phone manufacturer automatically shuts down when the battery voltage is lower than 3.0V, and the actual battery discharges to 2.7V. The following will hurt the battery. At 3.0V, there is at least 5% of the remaining battery, so even if you use automatic shutdown, don't worry too much about the battery, but use it every time. It is.
Proverbs 3: While charging by phone, the phone will explode?
This rumor may be based on the fact that this will cause the battery temperature to be higher than when charging only. If the temperature is higher, it still makes sense, because the energy conversion efficiency is usually only 85% when charging, and the remaining 15% of the energy is waste heat; when the phone is on, the baseband chip is also working, and it is also hot, especially on the phone. When one side of the phone is also attached to the face with poor heat dissipation, these three factors all increase the temperature on the battery.
But if it is said in the rumor, you should hear that a certain colleague is blown to the face every week? So the truth is that it will only cause the internal temperature of the mobile phone battery to rise, and there is no serious consequence.
Proverbs 4: Do not charge more than 12 hours. After charging for more than 1 hour after turning green light, you can charge 10% more?
In order to prevent battery explosion, the industry is designed with a failure rate of one-billionth of a grade. However, no matter how the process and process are controlled, a single step can not achieve such a high degree of safety, so two levels are used. There is one level on the charger and one level on the battery protection board. Each level guarantees a failure rate of one in 100,000 is achievable, then two simultaneous problems cause the battery explosion to be one in tens of billions.
The charger side is designed in such a way that it is charged in a constant current mode, and is charged at a constant voltage of 4.2V when charged to about 75% of the power. At this time, the current will gradually drop due to the increase of the battery voltage, and the charger is in The current is continuously judged until the current is less than a certain value, such as 20 mA, and then the green light is on.
What does the charger do next? It depends on what control chip you use to make the charger. The way the chip is controlled determines what the charger does afterwards.
Charge and discharge management chip in the charger
1. TI's BQ2057 series charging chip, Linear's LT1800 series is to let the charger completely turn off the charging circuit, then it will have no effect when placed on the charger for 10 hours.
2, the seat charger continues to carry out constant voltage charging, and strictly control the voltage does not exceed 4.2V, no doubt more charging for a few hours, can indeed increase the power. However, it is useless to increase the power by less than 0.1% from the green light to 4.2V.
3, Maxim's 1679 chip will also be seen inside many mobile phones. It uses pulsed charging. When it displays green light, the battery is 100% fully charged. Of course, it will not be overcharged if it is placed for another hour. . That is to say, not only do many chargers stop charging when they are green, but even the phone itself refuses to recharge the current.
4, the charger continues to charge, but its current control is very bad, accidentally make the battery exceeds 4.2V, and continue to run.那过充就å‘生了，什么时候电压到了5V就离爆炸ä¸è¿œäº†ï¼Œä¸è¿‡é™¤äº†å……ç”µå™¨å¤–ï¼Œç”µæ± ä¸€ä¾§ä¹Ÿæœ‰ä¿æŠ¤ï¼Œæ‰€ä»¥åžƒåœ¾å……电器å–çš„å¾ˆå¤šï¼Œç”µæ± çˆ†ç‚¸çš„äº‹æƒ…å´ä¸å¸¸è§ã€‚
典型垃圾充电器，别买
最åŽä¸€ç§æ˜¯å…¸åž‹çš„åžƒåœ¾å……ç”µå™¨ï¼Œä½ å¦‚æžœæ˜¯æ‰‹æœºæ’用这ç§ä¸œè¥¿å……电，手机内部的充电管ç†èŠ¯ç‰‡ä¹Ÿèƒ½åœ¨å……满时切æ–电æµã€‚ä½†å¦‚æžœä½ æ˜¯æŠŠç”µæ± æ‹¿å‡ºæ¥æŽ¥åœ¨è¿™ç±»å……电器上，那说ä¸å®šå°±è¦é¼“包，甚至爆炸了。
è°£è¨€äº”ï¼šå¤œé—´ç”µç½‘ç”µåŽ‹æ³¢åŠ¨æ¯”è¾ƒå¤§ï¼Œé”‚ç”µæ± æ¯”è¾ƒå¨‡è´µï¼Œæ‰€ä»¥ä¸è¦å¤œé—´å……电？
å¦‚æžœçœŸæ˜¯è¿™æ ·ï¼Œå…¨ä¸–ç•Œæ¯å¤©æ™šä¸Šéƒ½åæŽ‰å¥½å‡ ç™¾ä¸‡é¢—ç”µæ± ï¼Œæ—©èµ·èµ·æ¥ä¸€çœ‹ï¼Œç”µæ± 废了？实际情况是从220V市电å˜åˆ°5V电压，å†ä»Ž5V电压å˜æ¢åˆ°ç»™ç”µæ± 充电的电压，ä¸é—´ç»è¿‡å¥½å‡ é“电压å˜æ¢çš„æ¥éª¤ï¼Œæ¯ä¸€æ¥çš„输出电压都是åˆæ ¼çš„。å³ä¾¿220V那端å†æ€Žä¹ˆæ³¢åŠ¨ï¼Œéƒ½ä¸ä¼šå½±å“åˆ°ç”µæ± å……ç”µçš„ç”µåŽ‹ã€‚è¿™ç§è°£è¨€çš„说法改æ¢ä¸€ç§åœºæ™¯å°±æ˜¯ï¼šå°é£Žé²¶é±¼å°†ç™»é™†ç¦å»ºï¼Œæ‰€ä»¥è¯·åŒ—京市民远离公å›å’ŒæŠ¤åŸŽæ²³ç‰æ°´åŸŸï¼Œä»¥å…å±åŠç”Ÿå‘½å®‰å…¨ã€‚看上去是挺体æ¤äººçš„，实际那边å°é£Žå†å¤§ï¼ŒæŠ¤åŸŽæ²³ä¹Ÿä¸ä¼šå› æ¤é£Žæµªå¤§ä½œã€‚
ä¼ è¨€ï¼šé”‚èšåˆç‰©ç”µèŠ¯æ¯”18650电芯更安全？
è¿™ç§è¯´æ³•æœ‰ä¸€å®šé“ç†ï¼Œçˆ†ç‚¸åˆ†ä¸¤ç±»ï¼šä¸€ç±»æ˜¯ç”µæ± 内部çŸè·¯åŽæ¸©åº¦æ€¥å‰§å¢žåŠ å‡ºçŽ°ç‡ƒçƒ§ï¼Œäº§ç”Ÿçˆ†ç‚¸ï¼›ç¬¬äºŒç±»æ˜¯ç”µæ± å†…éƒ¨äº§ç”Ÿæ°”ä½“ï¼Œå¹¶æ²¡æœ‰ç‡ƒçƒ§ï¼Œæ°”ä½“æ’‘çˆ†äº†å¤–å£³ã€‚èšåˆç‰©ç”µèŠ¯å¾ˆå¤§ç¨‹åº¦ä¸Šé¿å…äº†ç¬¬äºŒç±»çˆ†ç‚¸çš„åŽŸå› ï¼Œèšåˆç‰©ç”µèŠ¯æ²¡æœ‰å°é—在固定体积内，一旦使用ä¸å½“，电解液产生了气体电芯就鼓起æ¥äº†ï¼Œæœ‰æ—¶è¿˜ä¼šæ’‘ç ´å¤–çš®ï¼Œæ°”ä½“æ³„æ¼å‡ºåŽ»ï¼Œç”±äºŽæ•…éšœç”µæ± è™½ç„¶ä¹Ÿä¼šå¤±æ•ˆï¼Œä½†é¿å…了爆炸。
åŒåž‹å·èšåˆç‰©ç”µæ± ，左边æ£å¸¸ï¼Œå³è¾¹é¼“åŒ…äº†ï¼Œä½†ä¹Ÿå› æ¤æ²¡æœ‰çˆ†ç‚¸
èšåˆç‰©ç”µèŠ¯æœ‰é¼“涨的空间
18650ç”µèŠ¯ä¹Ÿæœ‰å®‰å…¨é˜€ï¼Œä¸€æ—¦äº§ç”Ÿæ°”ä½“åŽ‹åŠ›å¢žåŠ åˆ°ä¸€å®šç¨‹åº¦é˜€é—¨ä¼šåˆ‡æ–ç”µè·¯ï¼ŒäºŽæ˜¯ç”µæ± å°±æ²¡æœ‰ç”µåŽ‹ä¹Ÿä¸èƒ½ç»§ç»ä½¿ç”¨äº†ï¼Œä½†æ˜¯å¾ˆå¤šå›½äº§18650的阀门并ä¸å¯é ，所以相比èšåˆç‰©å¯ä»¥é¼“包的特性æ¥è¯´ï¼Œ18650电芯确实更容易爆炸。
钢壳没有空间泄放气体，爆炸
而且采用三元ææ–™çš„é”‚ç”µæ± åªè¦æ£æžç‰©è´¨æš´éœ²åœ¨ç©ºæ°”ä¸ï¼Œä¸Žå…¶ä¸çš„æ°§ã€æ°´æŽ¥è§¦ï¼Œéƒ½æžæ˜“å‘生燃烧，我从å‰è¿˜è®¤ä¸ºæ¾ä¸‹ã€ä¸‰æ´‹è¿™äº›å“牌的ä¸ä¼šï¼Œåªæœ‰å›½äº§çš„垃圾电芯æ‰ä¼šç‡ƒçƒ§ã€çˆ†ç‚¸ï¼ŒåŽæ¥çœ‹è¿‡ä¸€æœŸé”‚ç”µæ± çˆ†ç‚¸çš„ç§‘æ™®èŠ‚ç›®ï¼Œå‘现åªè¦åˆºç©¿18650电芯他们全部都会燃烧。进å£é«˜æ¡£å’Œå›½äº§åªæ˜¯åœ¨å®‰å…¨é˜€é—¨ä¸Šæœ‰å·®å¼‚æ‰å¯¼è‡´äº†è¿›å£çš„更安全。
ä¼ è¨€ï¼šç”µé‡æ˜¾ç¤ºä¸ºä»€ä¹ˆç»å¸¸ä¸å‡†ï¼Ÿ
ç§»åŠ¨è®¾å¤‡çš„ç”µæ± ç”µé‡æ˜¾ç¤ºç›®å‰æœ‰2ç§åšæ³•ï¼Œä¸€ç§æ˜¯è‹¹æžœæ—©åœ¨iPhone3GS就开始用的库仑计测电é‡ï¼Œæ˜¯ç»Ÿè®¡æµè¿‡çš„电è·æ•°é‡ï¼Œæ‰€ä»¥ç²¾ç¡®åº¦å¾ˆé«˜ã€‚å¦ä¸€ç§æ˜¯ç”µåŽ‹æ‹Ÿåˆæ–¹å¼åˆ¤æ–电é‡ï¼Œè¿™ç§æ–¹å¼è¯¯å·®å¤§ã€‚
三元ææ–™é”‚ç”µæ± æ”¾ç”µæ›²çº¿
这是一个容é‡2600mAh三元ææ–™é”‚ç”µæ± ï¼Œ1A放电，25℃下的放电曲线，纵轴是电压，横轴是时间。手机生产ä¸é‡‡è´åŒä¸€åž‹å·ç”µæ± ï¼Œä¸€è‡´æ€§å¥½çš„ç”µæ± çš„æ”¾ç”µæ›²çº¿å‡ ä¹Žç›¸åŒï¼ŒæŠŠç”µé‡ç™¾åˆ†æ¯”对应的电压点记录下æ¥ï¼Œå°±å¯ä»¥å½¢æˆä¸€ä¸ªã€ç”µåŽ‹-电é‡ã€‘的对照表，åªè¦æµ‹é‡ç”µåŽ‹ï¼Œå°±èƒ½å¯¹åº”知é“剩余电é‡ã€‚这就是电压拟åˆçš„原ç†ã€‚但我们会å‘现，A段电压éšç”µé‡å˜åŒ–比较明显，B段电é‡å˜åŒ–很多，但电压ä¸æ€Žä¹ˆå˜ã€‚所以B段电é‡æ˜¾ç¤ºçš„è¯¯å·®å°±æ›´å®¹æ˜“å¤§ã€‚è¿™æ˜¯è¯¯å·®äº§ç”Ÿçš„åŽŸå› ä¹‹ä¸€ã€‚
—————————————————-
å¦ä¸€ä¸ªåŽŸå› 对误差产生更大的影å“：温度。
温度å˜åŒ–对电é‡æµ‹é‡è¯¯å·®çš„å½±å“
åŒä¸€é¢—ç”µæ± ä¸åŒæ¸©åº¦ä¸‹æ”¾ç”µæ›²çº¿ä¸åŒï¼Œä¸Šå›¾å°±æ˜¯åˆšåˆšé‚£é¢—ç”µæ± åœ¨15℃和25℃下的放电曲线，一个温度对应一æ¡çº¿ï¼Œä¸¤ä¸ªç»¿ç‚¹æ˜¯ç”µåŽ‹ç›¸åŒçš„点，按刚刚ã€ç”µåŽ‹-电é‡ã€‘对照表去显示电é‡ï¼Œå°±ä¼šé€ æˆ10%çš„è¯¯å·®ï¼Œé‚£ä¹ˆä½ è¯´è¿™ä¸è¦ç´§ï¼Œå¯ä»¥åœ¨5℃ã€15℃ã€25℃ã€35℃……ä¸åŒæ¸©åº¦ä¸‹æµ‹è¯•åŽå¤šåšå‡ å¼ å¯¹åº”è¡¨ï¼Œæ˜¾ç¤ºç”µé‡å‰å…ˆæµ‹æ¸©åº¦ï¼Œå†åˆ¤æ–ç”¨å“ªå¼ ã€ç”µåŽ‹-电é‡ã€‘对照表，问题ä¸å°±è§£å†³äº†å—ï¼Ÿæ²¡é”™ï¼Œè¿™æ ·ç¡®å®žèƒ½è¿›ä¸€æ¥å‡å°‘误差，但我è¦è¯´ï¼Œæ”¾ç”µæ›²çº¿çš„å˜åŒ–还éšè´Ÿè½½ä¹Ÿæœ‰ç›¸å½“大的å˜åŒ–呢，还éšç”µæ± 所处的寿命周期的ä½ç½®ä¹Ÿæœ‰å°å¹…度å˜åŒ–å‘¢ã€‚ä½ éš¾é“为了显示电é‡ï¼Œè¦åšå‡ºä¸€å¼ ã€nç§æ¸©åº¦Ã—mç§è´Ÿè½½Ã—qç§å¯¿å‘½ç‚¹â€” 电é‡ã€‘的对照表å—？差ä¸å¤šå¾—了，åˆä¸æ˜¯åšå®žéªŒã€‚于是低æˆæœ¬çš„移动设备ä¸æ„¿æ„用库仑计，也就干脆ä¸ç”¨æ•°å—显示了，æˆæœ¬åˆé«˜åˆä¸å‡†ï¼Œå¹²è„†è®¾å››ä¸ªLEDç¯ï¼Œæ¯ä¸ªç¯ä»£è¡¨25%电é‡ï¼Œç®¡ä»–准ä¸å‡†ã€‚
全文总结：
è¿™ç¯‡æ–‡ç« å¹¶æ²¡æœ‰è¯´çš„å¤ªå…¨ï¼Œæ¯”å¦‚ç£·é…¸é“é”‚ç”µæ± åœ¨ä½Žæ¸©ä¸‹ï¼ˆ-10℃）容é‡å‡åŠï¼Œåœ¨-30â„ƒä¸‹ç”šè‡³æ— æ³•å·¥ä½œï¼›é”‚ç”µæ± ä¸ºä»€ä¹ˆä¸èƒ½ä½ŽäºŽ0℃充电；过充和过放åŽç”µæ± 是如何æŸåçš„ï¼›æ‰‹æœºç”µæ± é¼“åŒ…æ˜¯ä¸æ˜¯ç”µæ± è´¨é‡é—®é¢˜ç‰ç‰ã€‚ä½†è¿™ç¯‡æ–‡ç« å·²ç»å¾ˆé•¿äº†ï¼Œä»¥åŽæœ‰ç©ºå†å†™å§â€¦â€¦
Lithium ion hydraulic tools,Aluminum alloy manual hydraulic tools,Hydraulic expansion pipe bending
ZHEJIANG KINGSIR VALVE CO., LTD. , https://www.kingsir-valve.com