Method for filling electrolyte into lead-acid battery
By adding electrolyte twice and controlling gas generation and air entry during charging and discharging, the problems of electrolyte overflow and corrosion in lead-acid batteries were solved, thus extending battery life.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUANGDONG TONGLI POWER TECH CO LTD
- Filing Date
- 2026-02-03
- Publication Date
- 2026-04-21
AI Technical Summary
Existing lead-acid batteries are prone to electrolyte leakage during charging and discharging, and oxygen entry can lead to corrosion of the positive electrode plate and sulfation of the negative electrode plate, affecting battery life.
The method involves adding electrolyte in two stages. After adding 70% to 90% of the electrolyte, the mixture is allowed to stand and charged to 80% to 90% saturation. Then, the mixture is discharged and the opening is covered. Next, 10% to 30% of the electrolyte is added and the mixture is charged to 95% to 100% saturation. Cotton cloth is used to reduce air entry and control gas generation and consumption.
It effectively prevents electrolyte leakage, reduces positive plate corrosion and negative plate sulfation, and improves battery life.
Smart Images
Figure CN121906100A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of battery technology, and more specifically to a method for adding electrolyte to a lead-acid battery. Background Technology
[0002] Lead-acid batteries are mainly composed of positive electrode plates, negative electrode plates, electrolyte, and container. They can be repeatedly charged and discharged. In secondary power supply applications, lead-acid batteries are widely used as power batteries for light electric vehicles such as electric motorcycles and electric bicycles due to their advantages of low cost, good high-current discharge performance, wide applicable temperature range, and high safety.
[0003] The main manufacturing process of lead-acid batteries includes: raw material preparation—lead powder production—plate paste application—plate formation—casing processing—battery assembly—initial charge and discharge—sealing and testing—capacity testing and grouping—packaging and storage. In the above process, battery assembly includes injecting electrolyte into the casing. Traditionally, the electrolyte is injected into the casing all at once, and the amount of electrolyte needs to be controlled to meet the requirements for lead-acid battery use. However, when the electrolyte is injected all at once, gas is generated inside the casing during the initial charge and discharge, causing the electrolyte to easily overflow. If the amount of electrolyte is too small, it is difficult to meet the requirements for lead-acid battery use. Furthermore, during the initial charge and discharge, when oxygen from the air enters the casing, it reacts chemically with the lead (Pb) on the negative electrode to generate compounds such as lead oxide (PbO). These additional oxides... The substances mix with lead sulfate to form more stable, coarse lead sulfate crystals that are harder to reduce during charging. These crystals cover the electrode surface, clogging the micropores of the active material, leading to a permanent decrease in battery capacity and severe electrode sulfation. Simultaneously, during discharge, the active material of the positive electrode is PbO2. In the presence of oxygen, it exacerbates the corrosion process of the positive electrode grid (usually a lead alloy). Oxygen, acting as an oxidant, promotes the oxidation of the grid metal, causing the grid structure to become brittle, lose strength, and even break. This not only increases the battery's internal resistance but also causes active material to detach, ultimately shortening the battery's lifespan. Furthermore, the entry of air disrupts the oxygen cycle mechanism inside the lead-acid battery. During normal charging, oxygen generated at the positive electrode diffuses to the negative electrode and is reused, but the mixing of external air interferes with this process, potentially causing abnormal internal battery pressure and promoting the electrolysis and evaporation of water in the electrolyte, resulting in water loss and further exacerbating sulfation and corrosion. Summary of the Invention
[0004] The purpose of this invention is to provide a method for adding electrolyte to a lead-acid battery. Using this method, electrolyte overflow during charging and discharging can be effectively avoided, sulfation can be reduced, and the service life of the lead-acid battery can be improved.
[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for adding electrolyte to a lead-acid battery, comprising the following steps: S1. Add the first electrolyte to the lead-acid battery. The capacity of the first electrolyte is 70% to 90% of the total capacity required by the lead-acid battery. After standing for a preset time, cover the opening of the lead-acid battery with a cotton cloth and charge the lead-acid battery once until the saturation of the lead-acid battery reaches the preset first saturation. Then stop charging the lead-acid battery.
[0006] S2. Discharge the lead-acid battery until the stored charge of the lead-acid battery is 0, then stop discharging.
[0007] S3. Remove the cotton cloth from the opening of the lead-acid battery, add a second electrolyte with the same concentration as the first electrolyte into the lead-acid battery, the capacity of the second electrolyte being 10% to 30% of the total capacity required by the lead-acid battery, let it stand for a preset time, and then charge the lead-acid battery a second time until the lead-acid battery is 95% to 100% saturated, at which point charging is stopped.
[0008] In the above method, after adding electrolyte to the lead-acid battery once, the capacity of the first electrolyte is 70% to 90% of the total capacity required by the lead-acid battery. There will be space above the lead-acid battery casing. Then, the lead-acid battery is charged once. During the first charge, the saturation of the lead-acid battery will gradually increase. At the same time, the material on the positive plate of the lead-acid battery reacts with part of the first electrolyte. Since the reaction process generates heat, the internal temperature of the lead-acid battery will rise, thereby consuming part of the first electrolyte and releasing some gas. However, since there is space above the gas in the lead-acid battery, even if gas is generated, the electrolyte will not overflow from the casing.
[0009] In this invention, although the capacity of the first electrolyte is 70% to 90% of the total capacity required for the lead-acid battery, leaving a small portion of the plates exposed to air, the use of cotton cloth to cover the openings of the lead-acid battery reduces the amount of air entering the battery. Therefore, during discharge, only a portion of the negative plate is oxidized. At the same time, it reduces the corrosion process of the positive plate, thereby reducing the brittleness and strength loss of the positive plate and decreasing the possibility of breakage. This not only reduces the internal resistance of the lead-acid battery and the shedding of active material, but also ultimately improves the service life of the lead-acid battery.
[0010] In this invention, after one charge-discharge cycle, a second electrolyte is injected. The concentration of the second electrolyte is the same as that of the first electrolyte, and the amount added is only a small fraction of the first electrolyte. Therefore, even if gas is generated during charging, only the second electrolyte will produce gas, and the amount of gas produced is small, thus reducing the likelihood of electrolyte overflow. Furthermore, after one charge and discharge, the negative electrode plate is partially oxidized. Upon the second charge, most of the oxidized portion of the negative electrode plate is reduced, thus virtually eliminating sulfation and preserving the battery's normal lifespan.
[0011] Furthermore, the preset first saturation of the lead-acid battery is 80% to 90% of the lead-acid battery saturation.
[0012] The above settings prevent the lead-acid battery from becoming too saturated after the first electrolyte addition, which would affect the amount of first electrolyte lost during the first charge-discharge process and the amount of second electrolyte lost during the second charge.
[0013] Furthermore, in S2, the following chemical reaction occurs on the negative electrode plate: 2Pb + O2 = 2PbO.
[0014] Furthermore, in S3, the following chemical reaction occurs at the negative electrode: Pb 2+ +2e - →Pb.
[0015] The above settings allow for better reduction of the oxidized portion at the negative electrode plate.
[0016] Furthermore, in S1, the negative electrode undergoes the following chemical reaction: 2H+ + + 2e - → H2↑; The following chemical reaction occurs at the positive electrode: 4OH- - → O2↑ + 2H2O + 4e - .
[0017] The above setup, due to the side reaction of water electrolysis that occurs at the end of charging or during overcharging, produces two main types of gases during charging: (1) When charging is nearing completion, the lead sulfate on the negative electrode plate has been basically reduced to lead, and the excess electrical energy will electrolyze hydrogen ions (H+) in the water. + (2) In the later stage of charging, the lead sulfate at the positive electrode has been converted into lead dioxide, and the excess electrical energy will electrolyze hydroxide ions (OH-) in the water. - Oxygen is generated during charging. This process produces gas, and to better prevent electrolyte overflow due to gas, a two-stage electrolyte addition process is employed in this invention.
[0018] Furthermore, in S1, during a single charge of the lead-acid battery, the charge amount is 0.8 to 1 times the rated capacity of the lead-acid battery.
[0019] The above settings enable most of the battery electrode materials to react with the first electrolyte and release most of the gas.
[0020] Furthermore, the air permeability of cotton fabric is 0.1–0.3 L / m² / s.
[0021] The above settings minimize the amount of air entering the lead-acid battery.
[0022] Furthermore, in S2, after the discharge stops, the stored charge of the lead-acid battery is checked twice or more to see if it is 0.
[0023] The above settings ensure that the lead-acid battery's stored capacity is zero after discharge, facilitating subsequent electrolyte refilling and recharging. Attached Figure Description
[0024] Figure 1 This is a flowchart of the process of the present invention. Detailed Implementation
[0025] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.
[0026] like Figure 1 As shown, a method for adding electrolyte to a lead-acid battery includes the following specific steps: S1. The first electrolyte is added to the lead-acid battery. At this time, the lead-acid battery is not fully saturated, and the capacity of the first electrolyte is 70%~90% of the battery volume. Let the capacity of the added first electrolyte be denoted as . z The capacity of the first electrolyte added includes the portion of the first electrolyte lost during one charge-discharge cycle, and the portion of the first electrolyte lost during one charge-discharge cycle is denoted as... x The units for z and x above are L (liters).
[0027] After standing for a preset time of 5 minutes, cover the opening of the lead-acid battery with a cotton cloth. The air permeability of the cotton cloth is 0.1–0.3 L / m² / s to reduce the amount of air entering. Charge the lead-acid battery once. During the first charge, the saturation of the lead-acid battery gradually increases until the saturation of the lead-acid battery reaches the preset first saturation level. Then stop charging. This allows most of the plate material to react with part of the first electrolyte, thereby releasing most of the gas generated by the plate material participating in the reaction and expelling it from the lead-acid battery. During this process, due to the side reaction of water electrolysis that occurs at the end of charging or during overcharging, there are two main types of gas generated during charging: (1) When charging is nearing completion, the lead sulfate on the negative plate has been basically reduced to lead, and the excess electrical energy will electrolyze hydrogen ions (H+) in the water. + (2) In the later stage of charging, the lead sulfate at the positive electrode has been converted into lead dioxide, and the excess electrical energy will electrolyze hydroxide ions (OH-) in the water. - Oxygen is generated, thus producing gas during charging. The chemical reaction is as follows: The negative electrode plate undergoes the following chemical reaction: 2H+ + + 2e - → H2↑; The following chemical reaction occurs at the positive electrode: 4OH- - → O2↑ + 2H2O + 4e - .
[0028] In this step, the first saturation is 80% to 90% of the lead-acid battery saturation. This avoids the lead-acid battery becoming too saturated after the first electrolyte addition, which would affect the subsequent second electrolyte addition and prevent the amount of first electrolyte lost during the first charge and discharge process and the amount of second electrolyte lost during the second charge.
[0029] In this step, during the charging process of the lead-acid battery, the charging amount is 0.8 to 1 times the rated capacity of the lead-acid battery. This allows most of the battery plate material to react with the first electrolyte and release most of the gas.
[0030] S2. Discharge the lead-acid battery to facilitate the refilling of electrolyte and subsequent recharging. Continue discharging until the stored capacity is 0. After discharging, check the battery's stored capacity at least twice to ensure it is 0, facilitating subsequent refilling and recharging. Record the remaining capacity of the first electrolyte as... y (Unit: L), thus we can obtain the partial capacity of the first electrolyte lost after the plate material reacts with part of the first electrolyte during a single charging and discharging process. x ,Right now x = z – y.
[0031] In this step, the following chemical reaction occurs on the negative electrode plate: 2Pb + O2 = 2PbO, which causes partial oxidation of the negative electrode plate when exposed to air.
[0032] S3. Remove the cotton cloth from the opening of the lead-acid battery. Add a second electrolyte of the same concentration as the first electrolyte into the lead-acid battery. The capacity of the second electrolyte should be 10% to 30% of the total capacity required by the lead-acid battery. Let the capacity of the added second electrolyte be A (unit: L), and the total capacity required by the lead-acid battery be B (unit: L). The capacity of the second electrolyte includes the portion of the first electrolyte lost during one charge-discharge cycle. x The capacity of the second electrolyte lost during the second charging process is denoted as C (unit: L). In this embodiment, the capacity C of the second electrolyte lost during the second charging process is equal to the capacity of the first electrolyte lost during the first charge and discharge process. x The value of C is 10% to 30%, meaning the range of C is... x* 10%~ x* 30%, then the amount of the second electrolyte added, A = (B - y )+C+ x In other words, the secondary electrolyte replenishment can compensate for the capacity of the first electrolyte lost during the first charging and discharging process, as well as the capacity of the second electrolyte lost during the second charging process. This satisfies the requirement that the second electrolyte is consumed during the second charging process and releases gas after the reaction, and also ensures that the secondary electrolyte replenishment reaches the battery's preset electrolyte capacity after the second charging.
[0033] After a preset resting time of 5 minutes, the battery is charged a second time. During the second charging process, the battery saturation gradually increases again until the battery saturation reaches 95%~100%, at which point charging is stopped. This allows the remaining small portion of the battery plate material to continue reacting with some of the second electrolyte, thereby completely releasing the gas involved in the reaction of the battery plate material. This prevents gas from remaining inside the battery after subsequent battery encapsulation, which could cause the battery to bulge.
[0034] In this step, the following chemical reaction occurs at the negative electrode: Pb 2+ +2e - →Pb. This allows for better reduction of the oxidized portion of the negative electrode plate.
[0035] In this embodiment, after adding electrolyte to the lead-acid battery once, the capacity of the first electrolyte is 70% to 90% of the total capacity required by the lead-acid battery. There will be space above the lead-acid battery casing. Then, the lead-acid battery is charged once. During the charging process, the saturation of the lead-acid battery gradually increases. At the same time, the material on the positive plate of the lead-acid battery reacts with part of the first electrolyte. Since the reaction process generates heat, the internal temperature of the lead-acid battery rises, thereby consuming part of the first electrolyte and releasing some gas. However, since there is space above the gas in the lead-acid battery, even if gas is generated, the electrolyte will not overflow from the casing. Although the first electrolyte accounts for 70% to 90% of the total capacity required for the lead-acid battery, exposing a small portion of the plates to air, the use of cotton cloth to cover the openings of the battery reduces air entry. Therefore, during discharge, only a portion of the negative plate is oxidized. Simultaneously, it reduces corrosion of the positive plate, decreasing its brittleness and strength, and reducing the likelihood of breakage. This not only reduces the internal resistance of the lead-acid battery and minimizes active material shedding, but also ultimately extends its lifespan. After one charge-discharge cycle, a second electrolyte is injected. This second electrolyte has the same concentration as the first electrolyte, but the amount added is only a small fraction of the first electrolyte. Therefore, even if gas is generated during charging, only the second electrolyte produces gas, and the amount is small, thus reducing the likelihood of electrolyte overflow. In addition, after a charge is discharged, the negative plate is partially oxidized. When it is charged again, most of the oxidized part of the negative plate is reduced. Therefore, sulfation will not occur, thus not affecting the normal service life of the battery.
Claims
1. A method for adding electrolyte to a lead-acid battery, characterized in that... Includes the following steps: S1. Add the first electrolyte to the lead-acid battery. The capacity of the first electrolyte is 70% to 90% of the total capacity required by the lead-acid battery. After standing for a preset time, cover the opening of the lead-acid battery with a cotton cloth and charge the lead-acid battery once until the saturation of the lead-acid battery reaches the preset first saturation. Then stop charging the lead-acid battery. S2. Discharge the lead-acid battery until the stored charge of the lead-acid battery is 0, then stop discharging. S3. Remove the cotton cloth from the opening of the lead-acid battery, add a second electrolyte with the same concentration as the first electrolyte into the lead-acid battery, the capacity of the second electrolyte being 10% to 30% of the total capacity required by the lead-acid battery, let it stand for a preset time, and then charge the lead-acid battery a second time until the lead-acid battery is 95% to 100% saturated, at which point charging is stopped.
2. The method for adding electrolyte to a lead-acid battery according to claim 1, characterized in that: The first saturation level is 80% to 90% of the saturation level of a lead-acid battery.
3. The method for adding electrolyte to a lead-acid battery according to claim 1, characterized in that: In S2, the following chemical reaction occurs on the negative electrode plate: 2Pb + O2 = 2PbO.
4. The method for adding electrolyte to a lead-acid battery according to claim 1, characterized in that: In S3, the following chemical reaction occurs at the negative electrode: Pb 2+ +2e - →Pb.
5. The method for adding electrolyte to a lead-acid battery according to claim 1, characterized in that: In S1, the negative electrode undergoes the following chemical reaction: 2H+ + + 2e - → H2↑; The following chemical reaction occurs at the positive electrode: 4OH- - → O2↑ + 2H2O + 4e - .
6. The method for adding electrolyte to a lead-acid battery according to claim 1, characterized in that: In S1, during a single charge of the lead-acid battery, the charge amount is 0.8 to 1 times the rated capacity of the lead-acid battery.
7. The method for adding electrolyte to a lead-acid battery according to claim 1, characterized in that: The air permeability of cotton fabric is 0.1–0.3 L / m² / s.
8. The method for adding electrolyte to a lead-acid battery according to claim 1, characterized in that: In S2, after the discharge stops, the stored capacity of the lead-acid battery is checked twice or more to see if it is 0.