Ⅰ： Electromotive force, internal resistance and terminal voltage of lead-acid battery:

1): Electromotive force: refers to the potential difference between the two poles, which depends on the relative density and temperature of the electrolyte.The relative density temperature coefficient of lead-acid battery is 0.00075, that is, the relative density decreases by 0.00075 when the electrolyte temperature increases by 1 ℃.

2): Internal resistance: the sum of electrolyte resistance, namely plate resistance, partition resistance and bonding resistance. In normal use, the resistance of the electrode plate, the resistance of the separator and the resistance of the connecting bar are generally small and negligible. The internal resistance of the lead-acid battery mainly depends on the electrolyte resistance, which is related to the relative density of the electrolyte.

3): Terminal voltage: refers to the voltage measured by lead-acid battery without load. When a load resistor R is connected to both ends of the battery, there will be current flowing through the circuit. At this time, the measured voltage at the positive and negative ends of the battery is lower than the electromotive force of the battery without load.

Ⅱ： Discharge characteristics of lead-acid battery: when the discharge current is constant (constant current discharge), the law of the battery terminal voltage changing with the discharge time is called the discharge characteristics of the battery.

The discharge process of lead-acid battery can be divided into three stages:

1): Initial discharge stage (I): During initial discharge, the battery terminal voltage drops rapidly from 14V to 12.6V, and the sulfuric acid in the gap of the electrode plate is consumed first. When the electrode plate is consumed to a certain extent, the sulfuric acid in the gap can be replenished with energy (the supply amount is approximately equal to the consumption amount) under the effect of the concentration difference inside and outside the gap of the electrode plate. Therefore, in the initial discharge stage, the terminal voltage of the battery in the discharge characteristics of the battery decreases sharply with the rapid reduction of the concentration of sulfuric acid in the electrode plate gap.

2): Relatively stable stage (II): The battery terminal voltage drops from 12.6V to 11.1V, which takes a long time. At this time, the supply and consumption of sulfuric acid in the pore of the electrode plate are basically balanced, and the battery discharge enters into a relatively stable stage.

3): Rapid decline stage (III): after relatively stable discharge for a long time. The terminal voltage drops rapidly, that is, from 11.1V to 10.5V. At this time, the sulfuric acid in the electrolyte is consumed in a large amount, and the sulfuric acid in the pore of the electrode plate cannot be normally replenished. If the battery continues to discharge at this time, the terminal voltage of the battery will drop sharply and enter a rapid decline stage, indicating that the battery discharge is nearing the end. In principle, the discharge termination voltage of single cell is 1.75V?

Ⅲ： Charging characteristics of lead-acid batteries: mainly study constant current charging. Main signs of the end of battery charging:

1): The terminal voltage of the single-cell battery increases to about 2.5V without increasing (charging termination voltage).

2): The specific gravity of electrolyte will not increase.

3): Due to the large amount of water electrolysis, a large number of bubbles appear in the electrolyte, presenting the so-called "boiling" state.

4)： Self-discharge of lead-acid battery: During storage, the capacity of the battery will gradually decrease due to internal self-discharge. Under normal circumstances, the capacity of the battery will decrease by about 2% every day it is stored. If it exceeds this value, it is abnormal.

5)： The relationship between lead-acid battery and temperature: lead-acid battery is a device for storing charge energy. Whether it is charged or discharged, it is a chemical reaction. The chemical reaction is directly related to the ambient temperature. When the temperature is lower than 15 ℃, the capacity will decrease. The lower the temperature is, the more the capacity will decrease. When the temperature is lower than 0 ℃, the capacity will decrease by 20% or even 40%.

6)： Capacity of lead-acid battery: refers to the storage capacity of the battery, which is usually expressed by the total amount of electricity discharged by the fully charged battery when the terminal voltage reaches the specified discharge end voltage of 10.5V.

Ⅳ： Factors affecting the capacity of lead-acid batteries:

1): Effect of discharge current on the capacity of lead-acid battery: the capacity of battery varies with the discharge current. The discharge current is small, and larger capacity can be obtained; The discharge current is large. Can you get smaller capacity?

2): Effect of electrolyte temperature on the capacity of lead-acid battery: When the temperature of electrolyte increases, the velocity of ion movement increases, and the kinetic energy obtained also increases. Therefore, the permeability increases, the resistance of electrolyte decreases, the degree of diffusion increases, and the electrochemical reaction increases. All these reasons increase the capacity of lead-acid battery.

3): Effect of relative density of electrolyte on the capacity of lead-acid battery: too high or too low relative density of electrolyte is unfavorable to the capacity of lead-acid battery. When the relative density of the electrolyte is high, although it can improve the electromotive force and capacity of the lead-acid battery, if the relative density of the electrolyte is too high, the viscosity of the electrolyte will increase, the diffusion speed will decrease, and the internal resistance will increase, but the terminal voltage and capacity will decrease. When the relative density of electrolyte is too low, the electromotive force and capacity of lead-acid battery will be affected.