First, the headache of the electric car battery problem
For electric bicycles, the momentum of development is extremely rapid. In recent years, the actual production per year has exceeded the social reserves. This is an amazing data, which indicates that the production and sales of electric vehicles are experiencing the most glorious history. In this booming market, making money is not too difficult. However, every advantaged industry has a "soft underbelly". If you want to ask the boss-level figure who fights in this industry, what is the most headache of distributing electric vehicles, the only answer is that the battery life is short.
Now most manufacturers are committed to battery warranty for one year, of course, the business is so publicized, but after half a year the problem came out, a large number of users come back, they are not coming to the second consumption, nor to introduce friends to buy a car, but to replace the battery . Even if the battery manufacturer fulfills the warranty promise, the users will not be satisfied, they will think that this is the quality problem of the electric car, the dealer has spent a lot of energy, or can not avoid being complained. Perhaps this problem lies in the battery manufacturer, but the battery manufacturer also has difficulties. The battery design and the cycle discharge test all indicate that the cycle life of the battery is indeed one and a half or even two years. The production process also strictly controls the quality according to the process flow. Many batteries will age after half a year. Some manufacturers have begun to try to replace lead batteries with long-life solid batteries, nickel batteries and even lithium batteries, but the high cost has lost the competitive advantage in the market of the above-mentioned households as the main consumer group. Many developers with pioneering spirit and enterprising spirit Was defeated mercilessly. We all know that many electronic products such as TVs and computers can last up to ten years, but manufacturers only provide one year warranty, while electric vehicle batteries last up to two years, battery manufacturers are hard to support. One year warranty, this is a helpless reality to disguise the battery life of electric vehicles is not ideal, while stabilizing users' consumer confidence. This "hard scalp" warranty method can withstand a short period of time in a short period of time, and the problem will always be highlighted. Therefore, there are many guerrilla-type manufacturers in this industry. They take a half-year cycle and do not establish a fixed customer base to seek their personal interests at the expense of the entire industry.
So how to improve the battery life, how to improve the battery environment and so on are all very disappointing but also concerned about the problem. In order to understand the way to extend battery life, we must first understand the failure mechanism of the battery, so as to prescribe the right medicine.
Second, the reason for the short life of electric vehicle lead battery
Since 1859, the Frenchman Gaston Plant discovered the phenomenon of lead-acid charge and discharge. Lead-acid batteries have always been the most widely used products in the battery field, such as cars, locomotives, ships, aircraft, and backup power supply equipment. Acid batteries, but we have heard a lot of dissatisfaction with lead-acid batteries from these fields. However, why the same products are on electric bicycles is a real "grievance". Below we explain the reasons for this problem in several aspects.
1. Reasons for working principle of lead-acid battery
The process of charging and discharging a lead-acid battery is an electrochemical reaction process. When charging, lead sulfate forms lead oxide, and lead oxide is reduced to lead sulfate when discharged. Lead sulphate is a substance that is very easy to crystallize. When the concentration of lead sulphate in the electrolytic solution in the battery is too high or the static idle time is too long, it will "carry" into a group and form small crystals. These small crystals will attract the surrounding area. The lead sulfate, like a snowball, forms a large inert crystal. When the lead sulfate is crystallized, it can not be reduced to lead oxide, but also precipitates on the electrode plate, causing the working area of ​​the electrode plate to decrease. This phenomenon is called Vulcanization, also known as aging. At this time, the battery capacity will gradually decrease until it is unusable. When the lead sulfate is piled up in a large amount, lead particles are attracted to form lead branches, and the lead bridge between the positive and negative plates causes a short circuit of the battery. If there is a gap in the surface of the plate or the sealed molded case, lead sulphate crystals will accumulate in these gaps and cause expansion tension, which eventually causes the plate to break off or the outer casing to rupture, resulting in irreparable physical damage to the battery. Therefore, the main mechanism leading to failure and damage of lead-acid batteries is the vulcanization that the battery itself cannot avoid.
2. Reasons for the special working environment of electric bicycles
As long as it is a lead-acid battery, it will be vulcanized during use, but lead-acid batteries in other fields have a longer life than lead-acid batteries used on electric bicycles. This is because lead-acid batteries for electric bicycles have a more easily vulcanized. Work environment.
1 deep discharge
The lead storage battery used in the car is only discharged in one direction during ignition. After ignition, the generator will automatically charge the battery without causing deep discharge of the battery. Electric bicycles are not likely to be charged when riding, and often exceed 60% of deep discharge. When deep discharge, the concentration of lead sulfate increases, and the vulcanization is quite serious.
2 large current discharge
The 20km cruise current of an electric car is generally 4A, which is higher than the battery operating current in other fields, and the overspeed overloaded electric vehicle has a larger operating current. Battery manufacturers have performed a cycle life test of 70% for 1C charging and 60% for 2C discharge. After such a life test, there are many batteries that can reach 350 cycles of charge and discharge cycles, but the actual use effect is far from the same. This is because high current operation increases the depth of discharge by 50% and the battery accelerates vulcanization. Therefore, the battery life of the electric three-wheeled motorcycle is shorter, because the body of the three-wheeled motorcycle is too heavy, and the working current is more than 6A.
3 high charging and discharging frequency
The battery used in the backup power supply field will only be discharged when the power is cut off. If it is stopped 8 times a year, it will reach 10 years of life, only 80 cycles of charging life, and the electric vehicle has a charge and discharge cycle of 300 per year. More than a few times are very common.
4 short charge
Since the electric bicycle is a vehicle, the charging time is not much. It is necessary to complete the charging of 36 volts or 48 volts in 20 hours in 8 hours. This requires an increase in the charging voltage (usually a single section of 2.7 to 2.9 volts) when charging. When the voltage exceeds the oxygen evolution voltage (2.35 volts) or the hydrogen evolution voltage (2.42 volts) of a single cell, the battery will open and vent due to excessive oxygen evolution, causing water loss, increasing the electrolyte concentration, and aggravating the vulcanization of the battery. .
5 can not be charged in time after discharge
As a means of transportation, the charging and discharging of the electric bicycle are completely separated. It is difficult to conditionally charge in time after discharge, and a large amount of lead sulfate formed after discharge will be vulcanized into crystal if it is not charged to lead oxide for more than half an hour. .
3. Reasons for lead battery production
Various battery manufacturers have adopted various methods for the particularity of lead-acid batteries for electric bicycles. The most typical method is as follows:
1 Increase the number of plates.
The original design of the single-frame 5-piece 6-piece system was changed to 6-piece 7-piece system, 7-piece 8-piece system, and even 8-piece 9-piece system. By reducing the thickness of the plates and the spacers, the number of plates is increased to increase the battery capacity.
2 increase the specific gravity of the battery sulfuric acid.
The original sulfuric acid of the floating battery is generally between 1.21 and 1.28, and the sulfuric acid specific gravity of the battery of the electric bicycle is generally about 1.36 to 1.38, which can provide a larger current and increase the initial capacity of the battery.
3 increase the amount and proportion of lead oxide active material active material.
Increasing lead oxide increases the electrochemical reaction species involved in the discharge, which increases the discharge time and increases the battery capacity.
Through these measures, the initial capacity of the battery satisfies the capacity requirements of the electric bicycle, and in particular, the characteristics of the large current discharge of the battery are improved. However, as the number of plates increases, the capacity of sulfuric acid decreases, and the battery heat causes a large amount of water loss. At the same time, the probability of micro-short circuit and lead-bridge bridging of the battery increases. Increasing the specific gravity of the sulfuric acid increases the initial capacity of the battery, but the vulcanization phenomenon is more serious. One of the most basic principles of sealed batteries is that after the positive electrode plate is deoxidized, the oxygen directly goes to the negative plate and is absorbed by the negative plate to be reduced to water. The parameter of the technical index of the battery is called “sealing reaction efficiencyâ€. This phenomenon is called “oxygenâ€. cycle". In this way, the battery has little water loss, achieving "maintenance-free", that is, no water is added. For this reason, it is required that the capacity of the negative electrode plate is made larger than that of the positive electrode plate, which is also called a negative electrode transition. Increasing the active material of the positive electrode plate inevitably reduces the transition of the negative electrode, the oxygen cycle becomes worse, the water loss increases, and the vulcanization is caused. Although these measures increase the initial capacity of the battery, they cause water loss and vulcanization, while dehydration and vulcanization contribute to each other, and the end result is to sacrifice the life of the battery.
There is also the problem of soldering the pole group. The place where the virtual welding is easy to occur is the plate. Each cell has 15 plates, which are 15 solder joints. One battery has 6 cells, and there are 90 solder joints. One battery consists of 3 12V batteries, and there are 270 solder joints. . If there is a virtual solder joint in the solder joint, the capacity of the single cell decreases, and the cell forms a backward battery, causing the entire battery to lag behind, and the battery will form a serious imbalance, which causes the battery to fail prematurely. Even if the virtual soldering control is in the first ten thousandth, there will be a set of batteries in each of the 37 batteries. There is absolutely no soldering, which is absolutely not allowed. The lead-calcium alloy grid cells will precipitate calcium during soldering to mask the problem of solder joints. As a result, many battery manufacturers prefer to use low-alumina alloy grids instead of lead-calcium alloys. The low-antimony alloy grid has a lower oxygen evolution and hydrogen evolution voltage, a larger battery output, a relatively serious water loss, and a battery that is more susceptible to vulcanization.
4. Reasons for the production of electric bicycles
Most car controllers have a line loss plug, and many dealers remove the speed limit to attract customers. Some car manufacturers simply remove the speed limiter from the factory, which can attract customers who value the speed and reduce the cost. Such a car has a very high current when driving at high speed, which will seriously shorten the battery life.
The minimum protection voltage of a 12V lead-acid battery is 10.5V. If it is a 36V battery pack, the minimum reserve voltage is 31.5V. At present, the undervoltage protection voltage of the controller used by most manufacturers is also 31.5V. On the surface, this is correct. However, when the 36V battery pack only has a voltage of 31.5V, due to the poor capacity of the battery, there will definitely be a battery voltage lower than 10.5V, and the battery is in an over-discharge state. At this time, the capacity of the overdischarged battery drops sharply. At this time, the damage to the battery is not only the single battery but the life of the entire battery. In fact, after the battery voltage is lower than 32V until 27V, the added capacity is less than 2 kilometers, and the damage to the battery is very large. As long as this happens 10 times, the battery capacity will be less than 70% of the nominal capacity. In addition, some users found that after the battery was under pressure for 10 minutes, the battery was not under pressure, and then the power was taken, which caused greater damage to the battery, and most of the car's instructions did not give the user a warning. At present, most controllers have adjustable potentiometers inside, and the vibration drift of this adjustable potentiometer is more serious. In the price competition, in the face of the user group that pays more attention to the appearance of the car, few products use precision multi-turn potentiometers that resist vibration. It is not surprising that such controllers drift after vibration.
5, the reason for charging equipment
One of the most widely circulated in the industry is that the battery is not worn out, it is burnt. In order to meet the short-time high-capacity charging of the electric bicycle battery, in the three-stage constant voltage current limiting charging, it is necessary to increase the constant voltage value to 2.47V to 2.49V. Thus, the oxygen evolution voltage of the positive electrode plate of the battery and the hydrogen evolution voltage of the negative electrode plate are greatly exceeded. In order to reduce the charging time, some charger manufacturers' products have increased the current of the constant voltage to float charging, so that after the charging indication is fully charged, it is not fully charged, and it is compensated by raising the floating charging voltage. Thus, the float voltage of many chargers exceeds the single cell voltage of 2.35V, so that a large amount of oxygen is still being evolved during the floating charge phase. The oxygen circulation of the battery is not good, so that it is continuously exhausted during the floating charge phase. The constant voltage value is high, which guarantees the charging time, but the sacrifice is water loss and vulcanization. The constant voltage value is low, and the charging time and charging power are difficult to guarantee. On the basis of improving the battery grid alloy of the battery, improving the gassing potential, improving the oxygen cycle performance, and improving the efficiency of the sealing reaction, the maximum charging voltage for controlling charging is below 2.42V, that is, below the hydrogen evolution potential. This will inevitably lead to an increase in charging time. This requires the addition of a depolarized negative pulse in the state of high current charging (current limiting charging) to improve the charging acceptance of the battery and to charge more when charging at a high current. Some power, shorten the charging time. 70% of the 2C current is charged, when the battery is relatively large in charging capacity, the battery is charged with a large current, and the damage to the battery is relatively small. The battery is basically no higher than the severe hydrogen evolution voltage. Once above the hydrogen evolution voltage, the battery will quickly lose water. To use such a charger, continuous charging and discharging must be used. If the charging is stopped for a few days, the battery will be severely vulcanized and will fail prematurely. When the user uses the battery, it is impossible to guarantee that it can be charged in time after each use. If the battery is not charged in time within a year, the vulcanization of the battery will accumulate. Most charger manufacturers say that the car manufacturer does not accept chargers that guarantee battery life due to price factors. It should be acknowledged that this is the case for most small businesses. However, large, large-scale enterprises that develop and do have high prices and cannot buy good chargers. Some charger manufacturers exaggerate certain features, and the efficacy of the finished product is not as good as its promotion. There are still a lot of functions that belong to the function of selling concepts, and the effect is limited.
6, other reasons
Many batteries can get better results in the single test. However, for tandem battery packs, the difference is due to the difference in capacity, open circuit voltage, state of charge, and degree of vulcanization. The monomer that is enlarged and has a poor state affects the entire battery, and its life is significantly reduced.
From the charging of the battery on the production line to the use of the car after the user purchases the car, there are many links, and the interval may even last for several months. During this period, due to the lack of recharging of the battery, the self-discharge produces a large amount of lead sulfate. Stacking crystals, the new battery that the user just bought may be a battery that has been aging or even reported.
When the battery manufacturer performs the warranty, the battery is not completely eliminated. After the battery is returned, the battery manufacturer re-inspects the charge and discharge. In the inspection, it is often found that more than 60% of the single cells are batteries that do not meet the return conditions. The reason is that in the series battery pack, the individual batteries fall behind to form a whole group of batteries, and the whole group returns. Many battery manufacturers have re-supplied, hydrated, desulfurized, and packaged the returned battery to provide users with the opportunity to improve the effective service life of the battery, reduce the scrap rate, and reduce the loss of partial claims of the battery manufacturer. Therefore, many dealers have already felt that the battery provided by the manufacturer is obviously "a generation is not as good as a generation."
Third, how to solve the vulcanization of the battery
To reduce the vulcanization of the battery and extend the life of the battery, it is first necessary to improve the working environment of the electric bicycle. Reduce the weight of the car body, remove unnecessary decorative parts, properly limit the speed, do not carry heavy objects, do supplemental charging when not using electric bicycle for a long time, it is best to charge in time after each discharge, to do undervoltage protection, To prevent over-discharge of the battery, the undervoltage protection for the nominal 24V should be set at 21.5V~22V, and the undervoltage protection for the nominal 36V should be 32.5V±0.5V. For the nominal 48V, it should be set at 44V~45V. This voltage reduces the continuation capability by less than 2 kilometers, but it can effectively extend the battery life. Every three months, go to the professional maintenance point to check the battery regularly and replenish the water in time. These methods are simple and easy to implement, and the economic costs are very low, but it is difficult to strictly observe them. Therefore, special equipment can be used for sulfur removal maintenance. These methods include:
1. Use desktop rapid desulfurization equipment
The working principle of the desktop fast desulfurization equipment is high voltage and high current pulse charging, and the vulcanization is eliminated by negative resistance breakdown. This method is fast and effective, and can obtain the temporary effect of eliminating vulcanization. However, high-voltage and high-current can remove sulfur and can remove active substances, which causes serious water loss and softening of the positive plate in eliminating vulcanization. Fatal damage to the battery, the battery after the sulfur removal twice by this type of equipment will be basically scrapped. In addition, the current professional maintenance point for a sulfur removal charge is basically between 60 and 80 yuan, which can extend battery life for up to half a year, and does not have significant economic benefits for users. At present, the professional battery maintenance shop owners on the market have already understood the harm of this method. Therefore, there has been a device for pulse discharge desulfurization. In fact, the fundamental principle has not changed, but the constant current from a constant high voltage has become a transient. Peak high pressure will still damage the active material of the plate, and friends who have used such products should be aware of this.
2. Select a desulfurization charger
At present, the desulfurization charger has three working principles, one is similar to the working principle of the desktop fast desulfurization device, and uses high voltage and high current pulse charging to remove sulfur through negative resistance breakdown. The method has been described above for the battery. Life expectancy is fatal and has been denied by the market. The second is to use a fast pulsed charge and discharge pulse, using instantaneous peaks to interfere with the vulcanization of the battery during charging. The other is to periodically reduce the lead sulfate crystals of the battery by using 10% to 20% overcharge. Both chargers can remove sulfur during charging, but it will cause undercharge or overcharge, and ignore the fact that the battery discharge process is the most important vulcanization process. Therefore, the effect is not satisfactory, most users are With the charger equipped with the electric vehicle, the desulfurization method of this repeated investment will be abandoned.
3. Use online lead-acid battery extension device
The online lead-acid battery extension is connected in parallel with the battery to prevent and eliminate vulcanization for 24 hours. This method is slower to repair, and the repair time is longer, often more than 120 hours, but both the charging and discharging processes can prevent and eliminate the vulcanization, and the repairing effect is very good. Because of the low voltage and low current, the extension does not have a strong impact on the battery plate, resulting in water loss and softening. This is a maintenance method that users can maintain consistently with one input, especially for new batteries with better quality. Extend the battery life by 2 to 5 times, and with one input, it can be accompanied by an electric automatic car. The next time the battery is replaced, the extension can continue to be used, which can save a lot of economic costs for the user. If the user replaces the battery once a year, a battery of 280 yuan, the user will spend 2800 yuan in the replacement of the battery in 10 years, a conservative calculation, if you use the extension to extend the battery life twice, you can save nearly half in 10 years. Battery cost.
The significance of adopting this method is great. The first is to bring tangible economic benefits to users, reducing the hassle of users. Secondly, it has improved the reputation of the car factory and provided conditions for expanding production. Thirdly, it solved the problem of battery warranty for electric vehicle dealers, reduced complaints, improved credibility, and increased profit points. At the same time, it also increased sales promotion schemes for store sales. Fourth, the battery manufacturer's claim costs can be greatly reduced. Fifth, improve the image of electric bicycles and expand the development of the overall market for electric bicycles. Sixth, improving the utilization rate of the battery is conducive to environmental protection.
Heavy-duty hydraulic sheet metal shears are suitable for compressing and cutting thin & light materials, production and living scrap steel, light metal structural parts, scrap car body, wheel hub, old home alliances, plastic non-ferrous metals(stainless steel, aluminum alloy, copper, etc), or used to compress and bale the above mentioned materials.
The machine is able to:
A) Prepressing and cut scrap
B) Cut bars
C) Packages light scrap
D) Squeeze and cut car bodies
E) We updated the pump to HY type, which has more novel and reasonable structure, with low noise, flow is larger with same motor power.
Aluminum Sheets Shear, Steel Sheets Shear, Iron Sheets Shear, Metal Sheets Shear, Copper Sheets Shear
Jiangyin Metallurgy Hydraulic Machinery Factory , https://www.jiangyinyejing.com