After the reform, with the development of society, China's technological level has continuously improved. At present, lead-acid batteries are widely used in the field of forklifts due to their advantages such as recyclability, low cost, safety and stability. This article analyzes the maintenance process of lead-acid batteries and proposes a reasonable application of the maintenance process, which enables timely and accurate maintenance of lead-acid batteries, thereby saving costs and extending their service life.

Keywords: forklift; Lead acid battery; Maintain the process; application

Introduction

Lead acid batteries are an important component in forklifts, with low operating costs, high safety, and recyclability. However, there may be certain issues when using lead-acid batteries in forklifts, and the maintenance process also needs to be optimized. The following analyzes various problems and explores the maintenance process of lead-acid batteries for forklifts.

Problems in the maintenance of lead-acid batteries for forklifts

(1) Improper maintenance of lead-acid batteries for forklifts can lead to premature battery failure, shortened lifespan, significant waste, and increased usage costs. (2) The maintenance personnel have low technical identification ability for battery status. (3) There are certain difficulties in developing a reasonable maintenance process for batteries.

Maintenance process of lead-acid batteries for forklifts

2.1 Analysis of the application methods of new battery maintenance technology

Generally speaking, new batteries should be maintained using cross current charging technology. In the actual charging process, the following operations need to be performed. Firstly, the electrolyte should be added according to actual needs. If there are seasonal changes, there should also be some differences in the density selection of the electrolyte. Generally speaking, the optimal state for adding electrolyte is when the liquid level is raised to 10-15 millimeters above the basic line. Secondly, after adding the electrolyte, it needs to be left to stand for 6-8 hours. At this time, the electrolyte will decrease, so it is necessary to replenish the electrolyte in real time to reach the specified value. If the actual temperature of the electrolyte is below 30 degrees, actual charging work can be carried out on the battery. Thirdly, in the process of power supply, comprehensive reference should be made based on the density of the electrolyte and the actual temperature to control the charging of the battery. Generally speaking, it can be divided into two stages for charging work. In the first stage of charging, the actual charging current is 1/15 of the rated capacity. If the temperature rises to 40 degrees, there will be bubbles overflowing from the electrolyte. At this time, charging needs to be stopped, and the current needs to be reduced to half of the original before proceeding with the second stage of charging. When using two-stage charging, the charging process takes 60-79 hours. Fourthly, when the battery is nearing the end of charging, the actual density of the electrolyte may decrease due to continuous charging. At this time, distilled water or dilute sulfuric acid needs to be added to increase the actual density, and subsequent charging should be carried out until the terminal voltage of the battery cell and the corresponding electrolyte density can further rise to the maximum value, and can be stabilized within 2-3 hours without increasing. At the same time, a large number of bubbles will appear in the electrolyte boiling state. At this time, the power supply needs to be cut off and the actual charging work should be completed. Fifth, for new or restored batteries, after the actual charging work is completed, they need to be discharged at a discharge rate of 20 hours for 1-2 hours, and then fully charged by supplementing the charging current mode. Then continue discharging for another 20 hours until the battery reaches 90% of its capacity, at which point the battery can be used normally.

2.2 Optimize battery structure, improve manufacturing process, and reduce the shedding of active substances

The active substances on the positive and negative plates of the battery are respectively fixed on the grid frame made of lead antimony alloy. Although the antimony content does not exceed 6%, the presence of antimony increases the water consumption and internal resistance in the battery. Moreover, antimony is easily resolved from the positive plate grid frame, which will inevitably lead to a decrease in service life. Generally, low antimony alloy grids with antimony content of 2% -3% are used. The active material fixed on the positive and negative electrode grid frames is prone to detachment during intense reactions, especially when the active material on the positive electrode plate is relatively loose, resulting in a decrease in battery capacity. Optimizing the structure of the separator can effectively reduce the amount of active materials. For example, lead-acid batteries in countries such as the United States and the United Kingdom commonly use bag type polyethylene separators, which pack the positive electrode plate in a bag. Polyethylene separators have small pore sizes, extremely thin substrates, and extremely low internal resistance, which not only reduce the detachment of active materials on the plates, but also effectively prevent short circuits between the positive and negative plates. In China, adsorption type glass fiber separators are commonly used, which have high porosity, large specific surface area, excellent tensile strength, and strong chemical corrosion resistance, which are conducive to the full reaction between active substances and electrolytes. The positive electrode plate is sandwiched in the middle of the negative electrode plate to form a plate group. The outermost two plates of the plate group are the negative electrode plates, which are uniformly discharged on both sides. Only one side of these two negative electrode plates undergoes a chemical reaction, so the thickness is generally only half of the thickness of the middle negative electrode plate. During the chemical reaction process of charging and discharging, the active material pure lead on the negative electrode plate tends to shrink in volume and passivate, reducing the capacity of the battery. In order to improve the disadvantage of pure lead, additives such as barium sulfate and lignosulfonate need to be added to the negative electrode active material. Adding phosphate, silicide and other additives to the positive electrode active material lead dioxide can increase the capacity by about 10%.

2.3 Application of Supplemental Charging Maintenance Technology

Forklift batteries often experience insufficient charging during use. In order to ensure the normal use of the vehicle and extend the service life of the battery, it is necessary to replenish the battery in a timely manner. Supplemental charging generally uses constant current charging. The following situations require supplementary charging. (1) The electrolyte dropped to 1.150 grams per cubic centimeter. (2) The voltage of a single battery drops below 1.75 volts. (3) In winter, the discharge exceeds 25% of the battery capacity, and in summer, the discharge exceeds 50% of the battery capacity. (4) The starter motor runs weakly and the lights are dim. (5) The battery is not used for a long time, exceeding one month. The specific operation for recharging is as follows: (1) Clean up. Remove the battery from the forklift, clean the dirt on the battery cover, unclog the vent hole on the filling hole cover, and remove the oxide on the pole post and wire joint. (2) Check the density and liquid level of the battery electrolyte. (3) Use a high rate discharge meter to check the discharge status of each individual cell battery. (4) Connect the positive and negative terminals of the battery to the positive and negative terminals of the charger. (5) During the constant current charging process. The charging current in the first stage is about 1/10 of the rated capacity of the battery, and the voltage of a single cell battery is 2.4 volts; The charging current in the second stage is reduced by half, charged to 2.5-2.7 volts, the electrolyte density returns to the specified value, and remains unchanged for 2-3 hours. Recharging usually takes 13-16 hours. (6) When the supplementary charging is about to end, the relative density of the electrolyte should be measured. If it does not meet the specified value, it should be adjusted using the same method as the initial charging.

2.4 Analysis of the application of desulfurization charging maintenance process

In general, the maintenance process of desulfurization charging can be refined into maintenance work carried out through charging and discharging cycles in the actual implementation process. Specifically, the operation can be analyzed from the following aspects. Firstly, it is necessary to enable the battery to discharge at its 20 hour discharge rate until its individual cell voltage is below 1.75 volts. The electrolyte inside the battery needs to be drained, and distilled water needs to be added to charge it, so that its density does not increase. Secondly, it is necessary to apply the initial charging current to charge it. If the overall density reaches 1.15 grams per cubic centimeter, the electrolyte needs to be poured out. Then it is necessary to add distilled water and carry out subsequent charging work to ensure that its actual density does not increase again. Then, it needs to be discharged at a 20 hour discharge rate until the overall battery voltage can be reduced to 1.75 volts, and the above charging work needs to be carried out again. Thirdly, the above process needs to be repeatedly carried out until the actual output capacity can reach 80% of the overall rated capacity when checked with a 20 hour discharge rate, and then it can be installed for application. If it cannot be achieved, the battery needs to be replaced and subsequent processing work needs to be carried out.