Answer: The shrinking battery life is currently a common problem of the battery, and it will be restored after the temperature is restored.
In fact, the short run of electric vehicles in winter is not a product quality problem, but physical characteristics. As the temperature drops, the activity of various substances in the lithium battery decreases, and the storage capacity also deteriorates.
Learn these tricks, electric cars can run at least 10 kilometers in winter
Although "low temperature" is the natural enemy of batteries, we can use some methods to alleviate and improve the problem of shrinking battery life in winter. Learn these tricks, there is no problem with lithium battery electric vehicles running 10 kilometers in winter.
First, try to avoid charging outdoors
Usually the best ideal temperature for the battery is between 15 degrees and 35 degrees, and the best room temperature for charging is 25 degrees. Outdoor charging in winter, if the battery capacity is around 0 degrees Celsius, the battery capacity is only 70%, and then if it drops by one degree, the battery capacity will also drop by 1%. Therefore, the charging environment temperature is very important to the battery capacity. On the premise of ensuring safety, it is possible to charge indoors if conditions permit, and it is best to charge during the day when the temperature is highest if there is no condition.
Second, don't wait for the electric car to run out of electricity before charging it.
When riding a bike in cold weather, pay attention to the battery capacity. The battery has only 25% power left, so you must charge it in time. Battery deficits often lead to a decrease in power storage capacity, so it is important to know the charging time. In the long run, you will find that the battery is much more durable than before.
Third, appropriately increase the charging time of electric vehicles
In winter, electric vehicles generally can only charge 70% of the electricity and the lights will jump. At this time, we can carry out floating charging. Taking 48V20Ah as an example, the charging time in summer is about 3-7 hours, and the charging time in winter is about 5-8 hours. This allows small currents to slowly enter the battery, which can also increase the power storage. But do not charge for too long to avoid danger.
Fourth, maintain good riding habits
Do not brake or accelerate suddenly when riding an electric bike, because the power consumed by a sudden brake, a sudden acceleration or a restart is several times that of a normal driving process, which makes the power consumption excessive and the battery more likely to be damaged. Therefore, pay attention to speed when riding and try to keep driving at a constant speed. When going uphill or starting, start lightly, and accelerate or brake slowly to avoid excessive current consumption.
Fifth, control the tire pressure
Affected by the weather, the tire pressure in winter is generally lower than that in summer, so ensure proper tire pressure. If the air pressure is insufficient, the resistance of the tires to the road surface when driving on the road is large, which consumes a lot of power. The tire has more air, the smaller the area of the tire that touches the ground, the smaller the resistance, and the longer the natural cruising range. Of course, don't hit the front tire too much.
Sixth, don’t drive beyond the load
The more overloaded, the more power consumption, and the shorter the natural cruising range. Because the battery itself is not active in winter, overloading will naturally make the snow worse, and because the road surface is slippery in winter, the risk of overloading is greater and the safety is lower.
Seventh, do not mix chargers
When charging, use the matching special charger, and do not mix other chargers. Mismatched chargers are more harmful to the battery, and the temperature is low in
The main processes of the power battery pack production line include:
1. Process of sorting and matching group.
2. Automatic welding process.
3. Semi-finished product assembly process.
4. Aging test process.
5. PACK inspection process.
6. PACK packaging process.
In recent years, with the advancement of lithium battery technology and the reduction of production costs, industrial design companies' lithium-ion electric scooters using lithium batteries as the main power source have also flown into the homes of ordinary people. Compared with traditional lead-acid batteries, lithium batteries are of high quality. Lightweight, long cycle life, high energy density, fast charging speed and other advantages. The service life of most lithium batteries is designed to be about 1,000 times (ordinary ternary lithium battery materials), which is 3-4 years. But this does not mean that the life of the lithium battery will end after 3-4 years of use. As long as you pay attention to these points, the life of the lithium battery of the electric scooter can be doubled! Let's take the current mainstream ternary lithium battery as an example. The mainstream manufacturer produces lithium batteries with 18650 cells. The main characteristics are high energy density, high cycle life, moderate manufacturing cost, but relatively high requirements for use environment and charging.
1. Lithium batteries are afraid of cold and heat, do not use them in extreme environments
Many people like to put lithium battery electric scooters in the sun in summer, or park in the yard or on the road in winter, which is very detrimental to the service life of lithium batteries. Lithium ions are in the electrolyte and electrode sheets. Migration rate is closely related to temperature. Theoretically, the temperature can be used normally between -20℃-55℃. In daily life, the use temperature of lithium battery between 5℃-35℃ will not harm the lithium battery. Users in the north Take the lithium battery home as much as possible in winter, do not put it outdoors, users in the south should avoid exposure to the sun in summer.
2. Do not charge and discharge lithium batteries frequently
Many people think that the number of cycles of charging the lithium battery hundreds of times in the manual of the electric scooter means that it can be used once as long as it is plugged and unplugged. In fact, this is a misunderstanding. The manual actually refers to the number of complete re-discharges. Lithium batteries are different from nickel-cadmium batteries. , Lithium battery does not have any memory effect and can be recharged anytime and anywhere. Charging when the battery has residual power will not only shorten the service life, but also maintain the battery and extend its recycling cycle. For lithium batteries, the correct approach is Slow charge instead of deep charge.
Three, use a suitable charger to charge
The chemical activity of lithium batteries is much more active than that of lead-acid batteries, and the requirements for chargers are higher. Once a brand-name charger or unsuitable fast charger is used, it will not only affect the service life of the lithium battery itself, but also seriously cause overheating. It causes the diaphragm to break and short-circuit and explode.
4. Do not "full charge" or "overcharge", do not need to "activate" the lithium battery
After buying lithium batteries for electric scooters home, many users still follow the lead-acid battery method, charging the lithium batteries for 10-12 hours the first three times, thinking that the lithium batteries need to be activated. In fact, this greatly affects the life of the lithium batteries. Even more bizarre people think that the superstition of trickle charging is to continue charging the electric scooter for an hour after it is fully charged to offset the interference of internal resistance. These practices are all wrong. The correct approach should be to directly charge it after it is fully charged. Unplug the power supply. Try not to charge the lithium battery of electric scooters overnight, which is prone to fire.
Five, do not need to be fully charged
When purchasing lithium batteries for electric scooters (18650 batteries), they are generally 2-3 cells. There are few fully charged batteries. Long storage time when fully
The current 3.7V 18650 lithium battery generally has a cycle life of about 500~1000 times, and the 3.2V 18650 generally has a life of more than 2000. Of course, the premise is that the qualified battery produced by a regular manufacturer, if it is a defective or counterfeit battery, the life will be very short. The service life of 18650 lithium batteries is only two to three years.
Lithium batteries can generally be charged and discharged 300-500 times. It is best to discharge the lithium battery partially rather than completely, and try to avoid frequent full discharge. Once the battery is off the production line, the clock starts to move. Regardless of whether you use it or not, the service life of lithium batteries is only two to three years.
The life of an 18650 lithium battery is generally 300 to 500 charging cycles. Assuming that the power provided by a complete discharge is Q, if the reduction in power after each charging cycle is not considered, the lithium battery can provide or supplement 300Q-500Q of power in its life. From this we know that if you charge 1/2 each time, you can charge 600-1000 times; if you charge 1/3 each time, you can charge 900-1500 times. By analogy, if it is charged randomly, the number of times is variable.
A saying that people often hear is that the life of a lithium battery is "500 times". The "time" in the principle of a lithium battery refers to the cycle life, which is a complete charge and discharge cycle. The test method in the industry is: discharge Depth × charge times = cycle life, the depth of discharge is 80% in numerical value, at least 625 charge and discharge times, that is, 80% × 625 = 500 (times).
In short, no matter how it is charged, it is constant to add a total of 300Q to 500Q of power. Therefore, we can also understand this: the life of a lithium battery is relate
Battery maintenance
After qualified lithium-ion batteries for electric bicycles leave the factory, the life and performance of the batteries depend to some extent on the use and maintenance of consumers.
(1) Matching of charger and battery.
Lithium-ion batteries for electric bicycles are badly charged, not worn out. This shows the importance of matching between chargers and lithium-ion batteries. There are two situations: one is that the new charger itself does not match the parameters supplied by the battery manufacturer. , The second is that the quality of the components of the charger itself is poor. When it is first used, it is still matched. As consumers charge and discharge cycles, the charger itself will drift due to temperature rise and components aging, causing the charging voltage and conversion current to drift. , The battery is damaged.
It is recommended that consumers and electric vehicle manufacturers should buy the chargers that are provided by the battery manufacturers. Don't charge the batteries because they are greedy for temporary cheapness. On the contrary, the gains outweigh the losses.
(2) Replenish electricity frequently and in time.
Consumers usually have a misunderstanding about the cycle life stated in the manual. They think that the life of the battery will be reduced by one charge, so each time the battery power is consumed to the controller's protection voltage of 31.5V before recharging starts. As everyone knows, this not only can not protect the battery, but also shortens the battery life. Therefore, consumers are reminded to recharge the battery in time when possible.
(3) It is strictly forbidden to continue riding when the indicator shows undervoltage.
Some consumers ride on the road halfway, and after the indicator shows the undervoltage condition, they take a break for a while and then ride for a while. This is very harmful to the battery. Severe over-discharge will cause the battery to salt or generate dendrites. , Short-circuit the battery and affect its life.
(4) The electric booster should be assisted as much as possible just after starting, climbing or overloading.
(5) When riding on rainy days, try to prevent the switches and joints from getting wet to prevent leakage.
Causes of thermal runaway of lithium-ion batteries
In essence, the thermal runaway of a lithium-ion battery is a positive energy feedback cycle: increased temperature will cause the system to heat up, and the system will heat up and increase the temperature, which in turn makes the system hotter. Thermal runaway is a very common phenomenon. From concrete curing to star explosions, thermal runaway may occur.
1. Overcharge often.
2. Unauthorized modification of the shell.
3. The ambient temperature exceeds 60C.
4. The tearing of the separator separating the negative electrode and the positive electrode of a lithium ion battery will cause a short circuit, and the short circuit will often cause thermal collapse.
The thermal runaway of lithium-ion batteries is important because the internal heat generation is much higher than the heat dissipation rate, and a large amount of heat is accumulated inside the lithium-ion batteries, which causes a chain reaction, causing the battery to catch fire and explode. Participating in the thermal runaway reaction is the cobalt oxide chemical in lithium-ion batteries. When this chemical is heated to a certain temperature, it starts to heat up by itself, and then develops into fire and explosion. In some cases, the release of pressure from this organic electrolyte can cause the battery to rupture. If exposed to a high temperature environment, or encounter sparks, it may also burn.
The phenomenon of thermal runaway and its intensity are related to the size, configuration and number of battery cells of the lithium-ion battery. Small lithium-ion battery packs have only a few lithium-ion battery cells, so the chance of thermal runaway spreading from the problematic battery cell to other cells is relatively low. The huge battery packs of the Boeing 787 are another matter: they are housed in a sealed metal box and cannot emit waste heat. When a battery cell is hot enough to ignite the electrolyte, the remaining battery cells will quickly follow up.
Lithium iron phosphate battery and Sanyuanli battery
Lithium iron phosphate battery: refers to a lithium ion battery that uses lithium iron phosphate as the positive electrode material. Its characteristic is that it does not contain precious elements such as cobalt, the price of raw materials is low, and the content of phosphorus and iron are abundant in the earth, so there will be no supply problems. It has a moderate working voltage (3.2V), large capacity per unit weight (170mAh/g), high discharge power, fast charging and long cycle life, and high stability in high temperature and high heat environments.
Advantages Compared with the more common lithium cobalt oxide and lithium manganate batteries currently on the market, lithium iron phosphate batteries have at least the following five advantages: higher safety, longer service life, and no heavy metals and rare Metal (low raw material cost), supports fast charging, and has a wide operating temperature range.
Disadvantages Lithium iron phosphate has some performance defects, such as low tap density and compaction density, resulting in lower energy density of lithium-ion batteries; material preparation costs and battery manufacturing costs are higher, and battery yield is low, consistent Poor sex; poor product consistency; intellectual property issues.
Ternary polymer lithium ion battery: A lithium ion battery using lithium nickel cobalt manganese oxide (Li (NiCoMn) O2) ternary cathode material as the cathode material. According to Ouyang Minggao of Tsinghua University, the ternary material mentioned in this survey refers to the ternary power lithium battery in the common saying that the positive electrode is ternary and the negative electrode is graphite. In actual R&D applications, there is another type of positive electrode that is ternary and the negative electrode is lithium titanate. It is usually called lithium titanate. Its performance is relatively safe and its life is relatively long. It is not a common ternary material.
Advantages The ternary lithium ion battery has high energy density and better cycle performance than normal lithium cobalt oxide. At present, with the continuous improvement of the formula and the perfect structure, the nominal voltage of the battery has reached 3.7V, and the capacity has reached or exceeded the level of lithium cobalt oxide batteries.
Disadvantages Ternary material power lithium-ion batteries are mainly nickel-cobalt-aluminate lithium-ion batteries, nickel-cobalt-manganese lithium-ion batteries, etc. Due to the unstable high-temperature structure of nickel-cobalt-aluminum, the high-temperature safety is poor, and the pH value is too high. Body flatulence, which in turn causes danger, is currently costly.
In comparison, the ternary polymer lithium-ion battery does have better characteristics than the lithium iron phosphate battery, but why its development has been hindered? The key to the development of new energy vehicles is also the development of the key battery that plagues mobile digital products. How to ensure that battery technology can meet the growing needs of consumers under safe conditions is not only the pursuit of automotive technology-related industry personnel, but also scientific research workers in the entire field
However, some consumers may temporarily stop their curiosity about new energy vehicles for some reasons. This is because there will be lingering fears about the spontaneous combustion of new energy vehicles. And this is exactly why the author writes this article today. If you don’t understand the fundamentals of new energy vehicles-the pros and cons of energy modules, and don’t understand the things you need to pay attention to during use, it’s actually no different from buying a timely bomb and putting it around.
The types of batteries used in electric bicycles include lithium-ion batteries, polymer lithium-ion batteries, nickel-hydrogen batteries, nickel-cadmium batteries, zinc-air batteries, and fuel power batteries.
1. Lithium-ion battery: The specific capacity of lithium-ion battery is better than that of nickel-metal hydride battery. For lead-acid batteries of the same capacity, the weight of lithium-ion battery is equivalent to a laptop computer, so that it can be used by women and children. Its life span can also be better than that of Ni-MH batteries.
The current mobile phone batteries basically use this kind of battery. The internal resistance of lithium-ion batteries is relatively large, and when used on electric bicycles, the lack of power will be felt when the battery is about to be completely discharged. The more important question of lithium-ion batteries is that the battery will explode in overcharge and overdischarge conditions. Cell phone batteries are all used single cells, and they are used together through an outstanding maintenance circuit, which basically eliminates the question of battery explosion.
For electric bicycles, it is necessary to use series-connected battery packs, and the level of clutter in the maintenance circuit of the series-connected battery pack far exceeds that of the single battery, and the cost of materials is also greatly increased. The current cost of an outstanding lithium-ion battery maintenance circuit is close to the price of the battery itself.
2. Polymer lithium ion battery: The blasting lethality of polymer lithium ion battery is lower than that of lithium ion battery. However, there is also the possibility of blasting and incineration. This is also the same as the lithium-ion battery needs to solve the problem.
3. Lead-acid batteries: Lead-acid batteries are the largest in number. Lead-acid batteries have the lowest quotation and are the most commonly used. my country is the largest producer of lead-acid batteries in the world. It contains less contaminated components and has good recoverability. The defect is that it is smaller than the volume. In other words, under the same capacity, the battery weight and volume are large. The current lead-acid batteries are basically developed from floating-charge batteries. Floating charge batteries are not suitable for rapid charging and high current discharge. Although technicians have spent a lot of sweat on effective improvements, they can be put into practical use, but their lifespan is still very poor.
4. Ni-MH battery: The specific capacity of nickel-hydrogen battery is much better than that of lead-acid battery, the life span of single battery is also better, and its high-current charge and discharge characteristics are also better than that of lead-acid battery. However, there are many questions about handling nickel-metal hydride batteries in series with battery packs. Once overcharging occurs, it will cause doubts about the melting of the single battery separators, causing the entire battery pack to quickly fail. Therefore, the key technical question of domestic nickel-metal hydride batteries is still the question of charger and battery management system, and this question has not led to the attention of various battery manufacturers and car manufacturers. Therefore, the development of nickel-metal hydride batteries is greatly restricted.
5. Zinc-air battery: Zinc-air battery is famous for its large specific capacity and low pollution. The battery is replaced by a battery replacement method, and the battery zinc plate is updated. It can be used for 160 kilometers to 220 kilometers by replacing the zinc sheet once. Shanghai has taken the lead in the country to launch the application of zinc-air batteries in electric bicycles. It has set up dozens of grid switching points throughout the city, creating a pioneer in the use of zinc-air batteries in electric bicycles. However, for the time being, it is not possible to carry out application experiments outside of Shanghai. At the same time, its operating cost is also several times that of lead-acid batteries. If so, further expand its application scale, there is a possibility of further reducing the application cost.
6. Nickel-cadmium batteries: The high-current characteristics of nickel-cadmium batteries are better than those of nickel-hydrogen batteries, and their anti-overcharge characteristics are also better than those of nickel-hydrogen batteries. my country is also a major producer of nickel-cadmium batteries in the world. Some people raised the question of cadmium pollution. my country is still exporting many nickel-cadmium batteries and their products to Europe. Europe only began to ban exports in 2006. According to the news broadcast by China Central Television, the Shenzhou No. 5 still uses nickel-cadmium batteries. of.
The purpose of paralleling lithium batteries is to increase capacity. Therefore, parallel charging of lithium batteries also has different design features compared with single-cell lithium batteries, which are mainly reflected in the consistency of charging current design and parallel batteries.
The characteristics of parallel lithium batteries are: the voltage remains the same, the battery capacity is added, the internal resistance is reduced, and the available power supply time is extended. The core content of parallel charging is the size and effect of parallel current. According to the parallel theory, the current of the main circuit is equal to the sum of the currents of the branches. Therefore, n parallel lithium batteries that have been combined into a battery pack must achieve the same charging efficiency as a single battery, and the charging current should be the sum of n lithium battery currents , Under the formula of Ohm’s law: I=U/R, this design is reasonable. However, the internal resistance of the batteries in parallel will also change. According to the parallel internal resistance formula, the total internal resistance of two parallel lithium batteries is equal to the ratio of the product of the internal resistance of the two batteries and the sum of the internal resistance. The parallel resistance will follow The number of parallel batteries increases and decreases. Therefore, the efficiency of parallel charging of lithium batteries can be realized on the basis that the current is less than the sum of the currents of n parallel lithium batteries.
When connecting lithium batteries in parallel, attention should be paid to the consistency of the battery, because a parallel lithium battery with poor consistency will fail to charge or overcharge during the charging process, which will damage the battery structure and affect the life of the entire battery pack. Therefore, when choosing parallel batteries, avoid mixing lithium batteries of different brands, different capacities, and different degrees of new and old. The internal requirements for battery consistency are: lithium battery cell voltage difference ≤10mV, internal resistance difference ≤5mΩ, and capacity difference ≤20mA.
In fact, after lithium batteries are connected in parallel, there will be a charging protection chip to protect the lithium batteries. When making parallel lithium batteries, lithium battery manufacturers have fully considered the changing characteristics of lithium batteries after parallel connection, and they have also carried out current design and The battery cell is selected, so the user needs to charge step by step according to the instructions of the parallel lithium battery to avoid possible damage to the battery caused by incorrect charging.
After the batteries are connected in series, the voltages are added together, and the currents are equal, which increases the voltage; the batteries are connected in parallel, and the voltage remains the same (provided that the batteries with the same voltage can be connected in parallel, otherwise the high voltage will charge the low voltage. If the difference is too large, it may be There is also danger), the current is equal to the sum of the batteries, which can often be regarded as increasing the battery capacity and can provide more current.
1. The power supply capacity of 48V20AH lithium ion battery is: 48V×20AH=960WH (watt hour)
2. The battery life of a 450W motor is: 960WH÷450W=2.13 hours.
1. There are many factors that affect the speed of electric vehicles, so they are all based on the endurance: under rated load, they can continue to drive for 2.13 hours. Two people, a load of 150KG, a 48V20AH lithium-ion battery can take a person to run 40 kilometers, if a person rides alone, the accelerator can run 70 kilometers. The size of the throttle greatly affects the mileage. The 48V12A battery can theoretically run 40-50 kilometers with a load of 300 catties.
Factors related to the mileage of electric vehicles;
The issue of how far the lithium-ion battery of a 48V electric vehicle can run is important to the problem of the battery capacity of the electric vehicle. Of course, there are many other objective factors. Electric vehicles rely on lithium batteries to supply power. The weight, speed, life span, mileage and starting performance of the vehicle are closely related to the battery.
Electric vehicle battery specifications are based on voltage (V) and capacity (AH). Consumers can look at the parameters of electric vehicles when choosing to buy electric vehicles. The specifications of electric vehicle batteries will be mentioned above.
The battery life of the 48v lithium ion battery is related to the capacity (AH) of the lithium ion battery and the motor power (W) of the electric vehicle. Now the electric bicycles on the market that meet the national standards generally use a 48v, 12AH lithium ion battery and a 350W motor.
With the development of lithium-ion battery technology, their theoretical endurance can reach 50km, and the actual endurance is still determined by the weight of the occupant and the weight of the vehicle.
If you value battery life, you can buy a 48V20AH lithium-ion battery, which can reach 70km. If the speed is required, you can also buy an electric motorcycle. The battery of electric motorcycles generally uses 72V22AH, and the battery life can reach 90km.
A 48V20AH electric vehicle with a new lithium-ion battery can travel 50-60 kilometers, and an old battery can be calculated based on driving habits.
If you want to go further, you can add a set of lithium-ion batteries to increase the cruising range.