Electric vehicle battery capacity and life of the relationship

For electric bicycle batteries, its life and capacity are the two most important indicators, we all hope to be able to do the battery capacity large and long life, but the two indicators have irreconcilable contradiction to a certain extent, so that an indicator to improve, will inevitably affect another indicator. We list some of the ways to increase capacity, and at the same time its impact on battery life. One, in the electric vehicle battery shell, to the extent permitted to increase the cell volume. This is a kind of effective method, if other aspects of design is reasonable, just increase the volume, increased the plate gate area, increasing the weight of the active material, lead to increase the capacity of this kind of way, is good for life, because it can effectively reduce the depth of discharge, so as to achieve the goal of improving life. We have the same battery using 5 respectively. 5 and 7 ah discharge. 5 ah discharge life cycle experiment, two kinds of discharge standard of shallow discharge the battery life is deep discharge twice, visible light discharge effect on the battery life is considerable. Second, under the condition of the same size in the appearance, there are two ways to increase capacity: 1, increase the thickness of the plate, mainly is the thickness of the plate. To use this method to increase the quantity of active substance, so as to achieve the purpose of increasing capacity. 2, decrease the thickness of the thin plate, improve the utilization rate of active material to increase the plate number, to improve the plate area, so as to achieve the aim of improving capacity. Increasing plate thickness is not, by contrast, operation steps, easier to implement. Rather thin plate is more advantageous to the increase of capacity, but due to the increase in the number plate, are negative interval increase, will inevitably lead to the diaphragm thinning, thus increase the risk of diaphragm dendrite penetrating, and increase the casting plate, coated board, assembly work. The two methods to improve the capacity, must increase the density of acid, in order to make sure there is enough acid to participate in the reaction, is made of the two methods the battery open circuit voltage are 13. 7 - 14 v (between This is far more than we can accept habit) , 5 a discharge can reach more than 140 minutes. Increase the density of acid effect on battery life has the following: 1, make the plate, especially the positive plate corrosion intensifies. 2, under the deep discharge circulation, accelerate the positive plate. 3, with the improvement of acid density, the solubility of sulfate, a big drop in the discharge process of lead sulfate saturation increases, easy to produce thick hard lead sulfate and cause negative sulphates. Especially in electric vehicles in the process of normal use, usually in the morning go to work, afternoon after work, among more than eight hours the battery is in a state of loss of electricity, are more likely to cause the sulfuric acid salinization. Three, by changing the conditions to change the positive plate - a The proportion of PbO2 and b - PbO2. a - PbO2 and b - PbO2 REDOX ability difference is very big, their electrochemical activity is different, b is type a has high discharge capacity, in different current density to devolve power, b - PbO2 has a capacity of more than a - is given PbO21。 5 - Three times, also some people think that a - 16% of the theory of PbO2 can only output capacity, and b - PbO2 output theory - 80% of capacity 90%. So, try to increase the b - in into PbO2 proportion, can effectively increase the capacity, the simplest way is, when the battery into increase current, reduce the electrolyte PH, adopt effective measures to cool again, restrain the battery temperature rise, such a b - into the battery The proportion of PbO2 will rise accordingly. But a - PbO2 size is bigger, the hard particles, in the positive active material can form network or bone, the structure of the positive electrode active material and complete, make electrode has a longer lifespan, so in the process of our into b - too much PbO2 will be harmful to life. Four, recently, the use of additives, all kinds of reports of can improve the battery capacity of the additive is increasing, but the vast majority are for deep filling put cycle for starting battery is not high. Claim that they also have some units of additives is not only beneficial to capacity, and can improve the filling deep cycle life, but in and after several units of such contact, I don't know whether it is for technical confidentiality reasons, they always say their additive increase capacity at the same time improve the principle of life. Above is the electric vehicle battery manufacturers commonly used way to increase capacity, but in addition to change the dimensions ( In national standards, this method will not be feasible) Also seems to have no a method of capacity and life of give attention to two or morethings at this time should be in find a balance between capacity and life. Through our investigation, electric bike users daily distance in 10 - 30 km, much more they will consider to choose other traffic tools. Therefore, we in the design of electric vehicle battery principle should be to ensure ride 10 - every day 30 km users, its battery life expectancy, according to this principle to consider the design capacity. The electric bicycle with 36 v and 24 v two main, usually ride of discharge current in 4 - 5. Between 5 a, so when we do life experiment, USES a 5 a discharge 1. 5 hours and 5. 5 a discharge 1 hour and two methods of discharge, through the experiment, we think, to achieve maximum under the condition of the two kinds of life, 151 & prime; 94′ The battery, weight of 98 in 3. 85 - 3. 95 kg, 5 a discharge time between 115 and 125 points, 151 & prime; 99′ The battery, weight of 99 in 4. 15 - 4. 25 kg, 5 a discharge time between 125 and 135 points is more appropriate, in this capacity, we can control the open circuit voltage of battery in the 13th. 2 - 13. Between 4 v, low capacity, will increase due to the depth of discharge affect life, on this basis to improve the capacity and will affect life due to the reasons why we discussed above.