Voltage current lithium battery and lead acid battery which capacity is large

The capacity of the energy storage battery is expressed by its ampere-hour AH (when the voltage is the same), or the capacity watt-hour WH, which is suitable for all occasions, that is, the capacity is only when the watt hours of the battery are the same.

The same voltage and current of the battery does not necessarily mean that the battery has the same capacity.

Press Battery Testing Certification (ptl-global.com) Reply:

AH is a unit that measures the capacity of a storage device. A represents current (amperes), h represents "hours", and Ah represents the capacity of the battery. Small-capacity batteries are commonly used for mAh, which is mAh.

18600mah = 18.6 Ah

Battery capacity is one of the important performance indicators for measuring battery performance. It represents the amount of electricity emitted by the battery under certain conditions(discharge rate, temperature, termination voltage, etc.)(discharge test can be performed by the JS-150D), that is, the battery capacity, Usually in Ampere hours(abbreviation, expressed in A.H., 1A · H = 3600C).

Battery capacity is divided into actual capacity, theoretical capacity and rated capacity according to different conditions. The formula for battery capacity C is C = <UNK> t0 It1dt(I integral to current in t0 to T1 time), and the battery is divided into positive and negative poles.

Battery capacity is divided into actual capacity, theoretical capacity and rated capacity according to different conditions.

The minimum capacity given at a discharge rate of 25 °C to the termination voltage is the capacity of the specified battery at the time of design and production, which is called the rated capacity of a certain discharge rate RH.

Square lithium-ion battery

Square lithium-ion battery

Battery capacity is generally calculated in AH(ampere hours), and the other is calculated in CELL(unit plate) several watts(W). (W/CELL)

1. Ah(ampere hour) calculation, discharge current(constant current) I × discharge time(hour) T. For example, if the 7AH battery has a continuous discharge current of 0.35 A, then the time can be continuous for 20 hours.

2. The charging time is 15 hours, and the charging current is 1/10 of the battery capacity. Fast charging will reduce the battery life.

Battery capacity refers to the amount of battery storage. The unit of battery capacity is “mAh”, and the Chinese name is mAh (when measuring large-capacity batteries such as lead storage batteries, for the sake of convenience, it is generally indicated by “Ah”, the Chinese name is An Shi, 1Ah=1000mAh). If the rated capacity of the battery is 1300mAh, that is, the current of 130mA discharges the battery, the battery can work for 10 hours (1300mAh/130mA=10h); if the discharge current is 1300mA, the power supply time is only about 1 hour (actual working time) There are some differences due to individual differences in the actual capacity of the battery). This is an analysis under ideal conditions. The current of a digital device in actual operation cannot always be constant at a certain value. (In the case of a digital camera, the operating current will be large due to the opening or closing of components such as the LCD display and flash. Change), so the battery can only provide a certain value for the power supply time of a device, and this value can only be estimated through practical experience.

Usually we say that the battery capacity is in time, which is based on a certain battery that has been determined.

For example, we say what the battery capacity of this mobile phone is; The battery capacity of this battery car is how much, are different for different batteries. For the battery voltage has been determined, without considering the actual voltage, it is only necessary to say that the time can represent the battery capacity.

However, for batteries of different voltages, we can not simply use ammeter to represent capacity, such as a 12V20AH battery, a 15V20AH battery, even if it is 20 AH, providing the same power load, the equipment can work normally, However, the duration is not the same, so the standard capacity should be in units of work.

For another example, a device can support 12V and can also support 24V. It is powered by a 12V(20 AH) battery and can provide one hour. Then using two series will become 24V(20 AH), and An Shi will not increase. However, the duration will be twice as long, so the capacity should be considered for the work contained in the battery at this time, not simply for safety time.

W(work) = P(power) * T(time) = I(current) * U(voltage) * T(time)

This discussion of battery capacity is meaningful. It must be realistic. Otherwise, there may be a claim that a cell phone battery is still larger than the battery of a battery. This is obviously not scientific.

To charge a battery with constant current constant pressure, and then discharge it with constant current, the amount of electricity emitted is the battery capacity, battery, nickel-metal hydride battery, etc., but lithium battery does not work. It has a minimum discharge voltage, that is, the discharge voltage can not be lower than 2.75 V, The lower limit protection voltage is usually 3.0 V. For example, if the lithium battery capacity is 1000 mAh, the charge and discharge current is 1000 mA, which is placed at 3.0 V in the battery's maximum voltage of 4.2 V, and the output capacity is the most true capacity of the battery.

The capacity of the battery is an important indicator of the performance of the battery. Generally, the time of discharge(hour) and the discharge current(ampere) are expressed as the general term, IE the capacity = discharge time × discharge current. The actual capacity of the battery, Depending on the amount of active substances in the battery and the utilization rate of active substances. The more active substances are used, the higher the utilization rate of active substances, and the larger the battery capacity. The smaller the capacity, the more factors that affect the battery capacity. The following are common:

(1) Effect of discharge rate on battery capacity

The capacity of the lead battery decreases with the increase of the discharge ratio, that is, the larger the discharge current, the smaller the calculated battery capacity. For example, a 10Ah battery can be discharged for 2 hours with a 5A discharge, IE 5 × 2 = 10; Then using 10A discharge can only emit 47.4 minutes of electricity, which is 0.79 hours. Its capacity is only 10 × 0.79 = 7.9 Angles. Therefore, for a given battery to discharge at a different rate, There will be different capacity. When we talk about capacity, we must know the hourly rate or rate of discharge. In simple terms, how much current is discharged.

(2) Effect of temperature on battery capacity

Temperature has a great influence on the capacity of lead-acid batteries. Generally, with the decrease of temperature, the decrease of capacity, and the relationship between capacity and temperature are as follows:

Ct1 = Ct2/1 + K(t1-t2). T1t2 is the temperature of the electrolyte, K is the temperature coefficient of the capacity, Ct1 is the capacity(Ah) of T1, and Ct2 is the capacity(Ah) of the temperature of T2. In the battery production standard, a temperature is generally specified as the rated standard temperature, If T1 is specified as the actual temperature and T2 is the standard temperature, the negative plate(usually 25 degrees Celsius) is more sensitive to the low temperature than the positive plate. When the electrolyte temperature decreases, the electrolyte viscosity increases, and the ions are greatly affected. Resistance, diffusion ability, Electrolytic resistance also increases, increasing the resistance of electrochemical reactions, and some lead sulfate can not be converted normally.

(3) Effect of termination voltage on battery capacity

When the battery discharges to a certain voltage value, the resulting voltage drops sharply. In fact, the energy obtained is very small. If the long-term deep discharge, the damage to the battery is quite large. Therefore, the discharge must be terminated at a certain voltage value. The cut-off discharge voltage is called the discharge termination voltage. Set the discharge termination voltage, It is of great significance to extend the service life of the battery. In general, the discharge termination voltage of the electric vehicle battery we maintain is 1.75 volts per cell, which means that a 12-volt battery has 6 grids, and the discharge termination voltage is 6 × 1.75 = 10.5 volts.

(4) Effect of Geometrical Size of Polar Plate on Battery Capacity

When the amount of active material is certain, the geometric area of the plate in direct contact with the electrolyte increases and the battery capacity increases.

1,Effect of the thickness of polar plate on capacity

The higher the plate thickness, the smaller the contact surface between sulfuric acid and active substance, the lower the utilization rate of active substance and the smaller the battery capacity.

2,The influence of plate height on capacity

In the battery, there is a large difference in the utilization rate of active substances in the upper and lower parts of the plate. Experiments have confirmed that at the beginning of the discharge, the current density of the upper part of the plate is about 2 to ~ 2.5 times that of the lower part of the plate. The difference gradually decreases with the discharge. But the upper part is more dense than the lower part.

3 Effect of polar plate area on capacity

The amount of active material is certain, and the larger the geometric area of the polar plate, the higher the utilization rate of the active material, and the larger the battery capacity. Under the same condition as the battery shell, the quality of the active material is unchanged, and the number of polar plates is increased by the use of thin polar plates. That is, the effective reaction area of the polar plate is increased, Thus, the utilization rate of active substances is increased, and the battery capacity is increased.

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