Battery capacity is equal to the product of discharge current and discharge time, generally indicated by ah, the factors affecting capacity can be broadly divided into two categories:
First, the design of production processes on the factors
1, the amount of active substances
2, the thickness of the plate
3, active substance perforation rate
4, the real surface area of the active substance
5, the center distance of the plate
6, the composition of active substances
Factors at use - factors of discharge conditions
1, discharge current density - that is, discharge speed
2, discharge termination voltage
3, electrolyte temperature
4, electrolyte concentration
The impact of capacity is first and foremost the problem of discharge, the impact of charging is indirect
The battery housing mainly has rubber and plastic two categories. Plastic grooves have polypropylene, polyethylene, ABS, AS. The use of plastic as a battery slot, light weight, high strength, small size, is to improve the battery than energy priority materials. Its molding process is simpler than the rubber groove process, can make geometric complex parts, can be in a variety of different colors, beautiful appearance, low price. Using plastic as a battery slot has more advantages than rubber, and is one of the ideal materials for high-performance power supply
Lead-acid batteries are reversible power supplies, or secondary batteries. Why is it reusable? Because its electrochemical composition is positive, negative plate and electrolyte, it is based on the bipolar sulfate theory as the basis for material change. After the discharge of the positive and negative plates, lead sulfate is generated, and after recharging, two electrode substances with electric potential are generated, namely lead dioxide (positive plate active substance) and lead (negative plate active substance). These two substances are stable in the sulfuric acid medium. This determines the conditions under which it can be used repeatedly over a long period of time.
Battery capacity is the amount of power that can be provided by external work or discharge of a fully charged battery under specified testing conditions.Capacity is an important index of battery.
The ampere hour (A.h) is usually used as a unit of measurement.
Battery capacity has two meanings: one is the theoretical capacity, which is calculated by Faraday's law, that is, the positive and negative active substances all react to release the electricity, and the other is the actual capacity, that is, the actual release of electricity under certain conditions. The actual capacity is lower than the theoretical capacity, accounting for 30% to 50% of the theoretical capacity, up to 60%, half of the capacity consumed inside the battery.
Weight-to-energy-volume-ratio energy is usually one of the assessment items. A battery in a certain weight or volume, large capacity, good battery. Conversely, it is poor. In order to improve the capacity efficiency, some people take measures such as reducing the thickness of the plate, increasing the number of tablets, increasing the area of the active substance and realizing its potential, reducing the resistance of the partition and improving the ion conduction of the electrolyte, and adding an active agent to improve the utilization rate of the active substance of the positive plate. These options have increased actual capacity, up to a maximum of 60 per cent of theoretical capacity. It is often the capacity that has increased and the service life has decreased.
The rated capacity of the battery is within the permissible discharge range, under the condition of specified discharge current, discharge time, termination voltage, electrolyte temperature and electrolyte density, the amount of power provided after full charge.The manufacturer takes the rated capacity of the battery as the main mark of the battery model.For example, for the 6-QA-120 battery, It is stipulated that the discharge current at 20h rate is 6A, the electrolyte density is 1.280g/ mL, the single cell termination voltage is 1.75V, and the rated capacity when the electrolyte temperature is 25℃ is 120A.h, namely C=It=6×20=120A.h
Under normal circumstances, the relationship between the three is: theoretical capacity > actual capacity > rated capacity
Lead-acid batteries are DC power supplies, a device that converts chemical energy into electrical energy. When the battery is discharged, it is used by the power supply equipment, and when charging, the electrical energy is converted into chemical energy for the next time. Every use of that is discharge, and then recharge can be restored to the original state, cycle dying, and even thousands of times. It is recognized as a simple structure, easy to use, economical and durable, reliable performance of chemical power supply. A battery made of lead and acid as an electrochemical reaction is called a lead-acid battery, also known as a lead battery.
Lead battery by use is divided into start-up, power traction, communication, equipment manipulation and other four categories of hundreds of models and specifications. Its voltage is calculated as a single body of 2V. The start-up battery is 6V, 12V, 24V. A single battery, regardless of capacity, is measured at 2V at static. When used, any combination can be made in series or in parallel according to the facility power.
Lead battery is widely used in automobiles, motorcycles, tractors, railway vehicles, mine tractors, ships, water navigation signs and communications, aviation, medical facilities, solar energy, etc., is an indispensable practical product strapped to all sectors of the national economy.
The product adaptability is strong, according to different needs, design and manufacture of different types, different functions of the battery, people call the battery is the "industrial bread", although the meaning is not quite accurate, but you can see that it in the national economy in the energy range is large.With the development of economy, more and more high requirements will be put forward for lead battery.
The lead battery has six parts:
(1) The positive plate group and the negative plate group are the main part of the power generation, which performs a redox reaction in the electrolyte.
(2) The function of electrolyte is in the electrochemical reaction converted from chemical energy to electrical energy, ionization into ions, conductive action and participate in electrochemical reactions.
(3) The partition acts as an isolation to prevent short circuits of the positive and negative plates. It is a porous body, can make electrolyte ion conduction, plate smooth electrochemical reaction, and has a higher perforation rate and less impurities, acid resistance, strong antioxidant and other conditions.
(4) The battery compartment is a container that holds the plate and the electrolyte. Can be made of hard rubber and plastic, with acid resistance, insulation, high strength conditions.
(5) The safety valve is to prevent overcharge gas production, due to the internal pressure is too large expansion or explosion.The main ingredient is halogenated rubber.
(6) Terminals are terminals connected to electrical facilities. Terminal current strength is designed based on the maximum power of the battery, which ensures that the maximum current, non-heating, non-corrosive, safe and reliable of the battery output.
Rated voltage: The voltage generated by chemical reaction between positive and negative electrode materials is called rated voltage.Different anode and cathode materials produce different voltages, such as: lead acid battery 2V/cell, lithium ion 3.6V/cell.
Open circuit voltage: The voltage measured by a battery in its untested state
Working voltage: the voltage displayed by the battery in the process of charging and discharging after connecting the load, also known as load voltage
Internal resistance: The resistance automatically generated by a chemical material in a cell.It can be measured by an internal resistor
Positive pole: Sign is +
Cathode：Sign is -
Discharge cut-off voltage: The voltage at which a battery reaches its terminal point during discharge testing
Discharge current: how much current is needed during discharge, and the charging current is the opposite
Overdischarge: Beyond the battery discharge cut-off voltage value, if the discharge continues, it may cause the battery to leak or degrade.
Overcharging: Once the battery reaches full, the extent to which the charge is continued, and overcharging may degrade the battery.
Discharge depth (DOD): The ratio of discharge power to the rated capacity of the battery.
Discharge rate: The charging state and discharge depth are battery retention values. The charge-discharge state is expressed as a percentage, with a full charge and full discharge of 100%. The charging state is called SOC; For example: DOD: 250mAh/800mAh x 100% x 31.25%.
Energy density: There are two means of representation, one is volume energy density (Wh\/l) and the other is weight energy density (Wh\/kg), which represents the energy that can be taken out per unit volume or weight. Often used to indicate the energy provided by various chemical materials.
Self-discharge: After the battery is fully charged, its electrical capacity will naturally decay without contact with the external circuit and in the condition of room temperature placement. During storage, the battery's storage capacity will gradually decrease, and the ratio of its reduced capacity to the rated capacity is called self-discharge rate. In general, the ambient temperature has a greater impact on it, and the excessive temperature accelerates the self-discharge of the battery. Battery capacity decay (self-discharge rate) is expressed by %/ month. The self-discharge rate of lead-acid battery is 4%/ month.
Cycle life: A battery goes through a charge-discharge called a cycle or a cycle. Under certain discharge conditions, the number of cycles the battery experiences is called cycle life before the battery capacity drops to the specified value. Battery in the use of repeated charge and discharge, the battery capacity will gradually decline, generally to the battery's rated capacity as the standard, when the battery capacity to 60% or 80% of its charge and discharge times called cycle life.
Colloidal batteries: another development belonging to lead-acid batteries, the simplest way is to add gel semen in sulfuric acid, so that sulfuric acid becomes collatic, electrolyte becomes colloidal battery
Memory effect: If the battery is not put out, if the battery is charged, the battery capacity may not return to the original level, but if forced deep discharge after charging, the capacity may be able to reply, usually this phenomenon usually occurs on nickel cadmium batteries, lead acid batteries do not have this problem.
String in parallel: Battery series to increase voltage to increase battery capacity in parallel
Heat out of control: when the battery charges its internal gas composite itself is a heat reaction, so that the battery temperature increases, floating charging flow increases, prompting the battery temperature to rise higher, if not timely heat exclusion, will cause heat out of control. The late voltage of the floating charge is too high, and the temperature of the surrounding environment of the battery increases, which will aggravate the loss of battery heat.
Floating charging pressure: floating charge refers to the battery and load in parallel, in the loaded state, by the charging device at the same time to the battery and load power supply process, floating charge voltage for floating charging voltage. Under floating charge, the battery is charged enough to supplement the battery self-discharge loss and the need for oxygen cycle, while the corrosion effect of the lattice alloy under floating charge pressure is minimal.
Average charging pressure: the average charging pressure than floating charging pressure is high, the purpose is to ensure that in a relatively short period of time, so that the battery can be fully charged, and at this voltage will not cause the battery overcharge, the charge to minimize damage to the battery.
The definition of layering: because the water generated during discharge rises to the upper level, so the difference in relativity generated by the upper and lower supervisors makes the lower level of gravity higher, and because the sulfuric acid produced by charging is high concentration, so it will fall to the lower layer, so the proportion of charging will be higher than the theory, such as the difference in the proportion of the upper and lower layers is called layering.
Life: During battery use, capacity or voltage decreases for a variety of reasons, and battery life is defined as the following three statements. When the load is no longer available, when the power required for the battery is reduced, when the real capacity becomes zero.