Dry batteries are mostly used in our daily life, mainly alkaline batteries and zinc-carbon batteries, but there is a lot of knowledge in it that we really don’t know, and there are even some doubts. I will analyze it in detail through this article. Voltage, you should be more clear after reading this article.
First of all, we clarify a few issues, and I will analyze them one by one.
- What types of dry batteries we always use? What are the corresponding voltages?
- Why is the voltage of alkaline batteries and zinc carbon batteries 1.5V?
- What is open circuit voltage? What is the load voltage? What are the differences? How to measure?
- Why is the open circuit voltage of carbon batteries higher than that of alkaline batteries?
- The voltage is gradually consumed with the use of electricity, how does the voltage drop?
- When the voltage is lower than how many volts, the battery cannot be used?
#1- What Types of Dry Batteries We Always Use? What Are the Corresponding Voltages?
We usually use more household dry batteries, mainly alkaline batteries. The main models of alkaline batteries are LR6/AA/AM3, LR03/AAA/AM4, LR20/D/AM1, LR14/C/AM2, 6LR61/9V, 23A/12V, 27A/12V, and so on. The main models of zinc-carbon batteries are R6/AA/UM3, R03/AAA/UM4, R20/D/UM1, LR14/C/UM2, 6F22/9V, and so on, button battery: AG13/LR44, AG3/LR41, AG8/LR55, AG10/LR54, AG12/LR43 and so on.
The voltage of 6LR61 and 6F22 is 9V, the voltage of 23A and 27A is 12V, except for these 4 models, the standard voltage of other batteries is 1.5V
– The reason why the voltage of 6LR61 and 6F22 is 9V is actually a combination of 6 1.5V cells in series, and we can also become a small battery pack.
– The voltage of 23A and 27A is 12V, which is the same reason. There are 8 button batteries assembled in series.
#2- Why Is the Voltage of Alkaline Batteries and Carbon Batteries 1.5v?
This is related to the main substances in the battery. Alkaline batteries and carbon batteries are both zinc-manganese dry batteries. The main components in the battery are zinc and manganese dioxide, and the two are separated by a separator. When the dry battery is working, the zinc in the negative electrode loses electrons, and the electrons reach the positive electrode along the wires in the circuit.
Expressed by a chemical equation, the reaction at the positive electrode is: Zn-2e-=Zn2+
The reaction at the negative electrode is: 2NH4++2E-=2nh3+h2
The total reaction is: Zn+2NH4+=Zn2++H2+2NH3
The MnO2 in the battery can react with H2 to generate MnO(OH) to eliminate the accumulation of H2 at the electrode; Zn2+ can react with the NH3 pole to generate [Zn(NH3)4]2+, which eliminates the accumulation of NH3 at the electrode, Make the response more fluid.
The voltage of the battery is officially determined by the chemical reaction of the positive and negative electrodes. From physical chemistry, we know that the positive and negative electrodes of the battery have standard electrode potentials, and the voltage is the difference between the two electrode potentials. We can understand the electrode potential as two steps with different heights, and the difference in the height of the steps is the voltage. For zinc-manganese batteries, the standard electrode potential of the positive electrode is +0.7710V, and the negative electrode is -0.7628V. The difference is (+0.7710)-(-0.7628)=1.5338V, which is the voltage marked on our battery.
From this, we can see that the voltage of a battery is not determined by its shape and brand, but depends on the chemical substances in it. Therefore, our commonly used batteries are all zinc-manganese batteries with a voltage of 1.5V, while other types of batteries, such as lead-acid batteries, have a voltage of 2V because of different reactants. For example, our mobile phone battery is a lithium-ion battery, the voltage is 3.7V; the voltage of Ni-MH and Ni-Cr batteries is 1.2V; the voltage of lithium manganese button batteries such as CR2016, CR2032, CR2025 is 3V.
#3- What Is Open Circuit Voltage? What Is the Load Voltage? What Are the Differences? How to Measure?
The open-circuit voltage is the voltage without load and the voltage is measured when the external resistance is 0.
The load voltage is the voltage added with a resistor, and generally refers to the voltage when it is used in an electrical appliance. Therefore, the voltage measured by the same battery under different load conditions is different.
According to IEC60086-2:2015, the voltage range of alkaline batteries is 1.5-1.68V, and the voltage range of carbon batteries is 1.5V-1.73V. This voltage refers to the open-circuit voltage of the new battery, within this range All qualified.
In our actual production process, from a technical point of view, the voltage is generally controlled. The open-circuit voltage of alkaline batteries is generally controlled at 1.62V-1.65V, and the open-circuit voltage of carbon batteries is generally controlled at 1.63V-1.68V. Why do we need to Control the voltage? It is not because the higher the voltage, the better, nor the lower the better. It is necessary to consider not only the voltage but also the safety issues during storage and use.
We can measure the open-circuit voltage and load voltage with a voltmeter. This is relatively simple. For load voltage, add a load test.
#4- Why Is the Open Circuit Voltage of Zinc Carbon Batteries Higher Than That of Alkaline Batteries?
The main components and chemical reaction principles of alkaline batteries and zinc-carbon batteries are the same, but the electrolyte in alkaline batteries becomes alkaline, and the electrolyte of zinc-carbon batteries becomes acidic, and the ratio of electrolytes is different. There is a difference between manganese dioxide used in the production of carbon batteries and manganese dioxide used in the production of alkaline batteries.
Compared with alkaline batteries of the same model, carbon batteries have much less power. During storage and use, the voltage of carbon batteries drops faster than alkaline batteries.
#5- The Voltage Is Gradually Consumed With the Use of Electricity, How Does the Voltage Drop?
Alkaline batteries and carbon batteries are both disposable batteries, and their voltage gradually decreases with discharge. The descending process is an inverse parabolic shape, as shown in the below chart.
We will find a problem, that is, between the high voltage section (1.2V-1.5V), the voltage drops quickly, and then the voltage drops slower and slower, which is a characteristic of dry battery discharge. Familiar with this feature, we can purchase different batteries according to different electrical appliances. For example, high-power electrical appliances use alkaline batteries, and low-power discharger alkaline batteries and zinc-carbon batteries can be used.
#6- When the Voltage Is Lower Than How Many Volts, The Battery Cannot Be Used?
The voltage range of alkaline batteries is 1.5-1.68V, and the voltage range of carbon batteries is 1.5V-1.73V. So can the battery be used to 0V? This is not allowed. Generally, the lowest working voltage of household appliances is 0.9V. When the voltage of the battery is lower than 0.9V, the electrical appliances will hardly work.
For some electrical appliances with electric motors, such as electric toy cars, its minimum working voltage is higher. So sometimes when the battery is placed in the electric toy car and cannot be used, you can take it out to test the lower voltage. If the voltage is higher than 0.9V, then we can continue to use the battery in low-power electrical appliances, such as in the remote control.
For dry batteries, if they are placed in electrical appliances and cannot work, we must take them out in time. If they are not taken out in time, the battery will continue to discharge and the voltage will continue to drop to 0.6V or even lower, so that the battery may leak. . Especially for carbon batteries, zinc is used as the negative electrode material of the battery, and at the same time, it is the outer shell of the battery. When it participates in the chemical reaction, it also assumes the role of the outer shell. Therefore, if it is used all the time, the voltage will drop, which will cause the outer shell to penetrate. There is a possibility of liquid leakage.