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Introduction

Forklifts, as important handling equipment in logistics, warehousing, industrial production and other fields, are mostly powered by lead-acid batteries. In the daily use of forklifts, lead-acid batteries sometimes experience deep discharge. Deep discharge not only may cause forklifts to fail to operate normally and affect work efficiency, but also can cause serious damage to the lifespan and performance of the battery. If the lead-acid batteries after deep discharge can be activated in a timely and effective manner to restore some or all of their performance, it is of great significance for reducing operating costs and ensuring the continuity of production operations. This article will deeply explore the activation methods of forklift lead-acid batteries after deep discharge, and at the same time analyze the causes and hazards of deep discharge, providing comprehensive and practical technical references for relevant personnel.

The reasons for deep discharge of lead-acid batteries in forklifts

Bad usage habits

1. ** Excessive discharge ** : During the operation of a forklift, if the operator fails to pay timely attention to the battery power indicator and continues to use the forklift until the battery power is almost exhausted, it will lead to excessive discharge. For instance, in some logistics warehouses, forklifts may need to operate continuously for long periods of time. If the staff, in order to catch up with the schedule, keep the forklifts running without reasonably planning the operation time and without timely charging, it is very likely to cause deep discharge of the battery.

2. ** Frequent high-current discharge ** : When forklifts are in operation such as starting, accelerating, and climbing slopes with heavy objects, the battery needs to output a large current instantaneously. If such working conditions occur frequently, such as frequently handling overweight goods, it will accelerate the shedding of active substances on the battery plates and the formation of lead sulfate crystals, leading to a decline in battery performance and a greater risk of deep discharge. A set of forklift batteries, calculated based on a lifespan of 1,500 cycles, will have its lifespan shortened by at least half if it undergoes deep and high-current discharge for a long time.

3. ** Long-term idle without charging ** : When forklifts are idle for a long time due to equipment updates, fault repairs, etc., if the battery is not regularly charged and maintained, the battery will gradually consume power through self-discharge. As time goes by, the power will continuously decrease, eventually leading to excessive deep discharge. Under normal circumstances, the self-discharge rate of lead-acid batteries can reach 3% to 5% per month when they are idle. If a vehicle is left idle for half a year without charging, the battery power may drop to an extremely low level, causing excessive deep discharge and affecting its subsequent performance.

Equipment failure factors

1. ** Charging System failure ** : Problems with the charging system of forklifts are one of the common causes of deep discharge of the battery. For instance, a malfunction of the charging controller may prevent the battery from charging normally, and it may be unable to adjust the charging voltage and current according to the battery's charging status, leaving the battery in an undercharged state for a long time and eventually leading to excessive deep discharge. In some industrial equipment, a malfunction of the charging controller may also cause the battery to fail to charge normally. The charging controller is unable to adjust the charging voltage and current according to the charging status of the battery, causing the battery to remain in an undercharged state for a long time and eventually leading to excessive deep discharge.

2. ** Electrical Equipment Leakage ** : In the electrical system of a forklift, if there are aged or damaged electrical components, such as aging circuits, damaged insulation layers, faults in the switch of the interior lights or the motor of the door lock, leakage may occur. Even when the forklift is not in use, these leaking electrical components will still continuously consume the battery's power. If the leakage is relatively serious, after a period of time, the battery power will be gradually depleted, resulting in deep discharge.

The influence of environmental factors

1. ** Low-temperature environment ** : Under low-temperature conditions, the viscosity of the electrolyte in the battery increases, the diffusion rate of ions slows down, and the internal resistance of the battery increases. This leads to a decline in the battery's discharge performance and a reduction in the amount of electricity it can release. For instance, in the cold winter, it is difficult to start a forklift. The driver may attempt to start the vehicle multiple times, and each start consumes a large amount of battery power. Due to the fact that the battery itself can release less electricity in a low-temperature environment, after multiple starts, the battery is prone to excessive deep discharge. Some energy storage devices used outdoors, such as the batteries of solar street lamps, also have a reduced charging efficiency in low-temperature environments. If the energy collected by the solar panels during the day is insufficient to replenish the electricity consumed by lighting at night, and the low temperature further intensifies the self-discharge of the battery, it is easy to cause excessive deep discharge of the battery.

2. ** High-temperature environment ** : A high-temperature environment will accelerate the self-discharge rate of the battery, intensify the evaporation of the electrolyte, and speed up the internal chemical reactions of the battery, resulting in a decrease in battery capacity. If forklifts are used for a long time in high-temperature environments with air conditioners, audio equipment and other devices, the rate of battery power consumption will increase, and self-discharge will also accelerate. Under the dual effect, the battery is more likely to experience excessive deep discharge. High temperatures may also accelerate the corrosion of battery plates, further affecting battery performance and shortening its service life. In some industrial applications, batteries are installed in poorly ventilated high-temperature environments, such as UPS batteries near boiler rooms. Due to long-term exposure to high-temperature conditions, they are more prone to excessive deep discharge.

The harm of deep discharge to forklift lead-acid batteries

The sulfation of the plates has intensified

When a lead-acid battery discharges, the active substances on the plates react with sulfuric acid to form lead sulfate. Under normal circumstances, lead sulfate will be reconverted into active substances during charging. However, after deep discharge, a large amount of coarse and difficult-to-reduce lead sulfate crystals will form on the plates, which is the sulfation phenomenon of the plates. The resistance of the plates increases after vulcanization, which hinders the electrochemical reactions inside the battery, deteriorates the battery's charging and discharging performance, and reduces its capacity. Moreover, the more severe the degree of sulfation, the more difficult it is to restore the battery's performance. In severe cases, it may even lead to battery scrapping.

The battery capacity has dropped significantly

Deep discharge will cause excessive consumption of the active substances inside the battery, and some of the active substances will lose their activity in irreversible chemical reactions. This directly leads to a significant reduction in the amount of electricity that the battery can store and release, resulting in a marked decrease in the forklift's endurance. A battery that was originally fully charged to meet the operation requirements of one shift may only be able to work for a short time after deep discharge, unable to meet the normal working intensity and seriously affecting work efficiency.

Shorten the battery life

Due to problems such as plate sulfation and active material loss caused by deep discharge, the battery's performance deteriorates continuously during subsequent charge and discharge cycles. The number of charge and discharge cycles that batteries can withstand has been significantly reduced. Batteries that could have been used for several years may need to be replaced in a short period of time due to deep discharge, increasing the usage cost and equipment maintenance workload.

The activation method of forklift lead-acid batteries after deep discharge

Detection and evaluation

Before attempting to activate a deeply discharged forklift lead-acid battery, a comprehensive inspection and evaluation of the battery is required to determine its specific condition and thereby select an appropriate activation method.

1. ** Visual inspection ** : Check whether the battery casing has any damage, deformation, leakage or other conditions. If the battery casing is damaged, it may cause the electrolyte to leak, affecting the battery performance and even posing safety hazards. At this time, it needs to be handled with caution. If necessary, replace the battery casing or the entire battery pack.

2. ** Voltage Detection ** : Use a professional multimeter to measure the open-circuit voltage of the battery. Under normal circumstances, when a forklift lead-acid battery is fully charged, the voltage of a single cell is approximately 2.1V to 2.2V, and the voltage of the entire battery pack varies depending on the battery specifications. If the measured voltage is significantly lower than the normal range, it indicates that the battery has severe deep discharge.

3. ** Electrolyte Inspection ** : Open the battery's liquid injection hole and observe the liquid level and density of the electrolyte. The normal electrolyte level should be at a certain height above the plates. If the level is too low, it may be that the electrolyte has dried up or leaked, and distilled water or special electrolyte should be replenished in time. Meanwhile, use a hydrometer to measure the density of the electrolyte. The density of the electrolyte in lead-acid batteries is generally between 1.28g/cm³ and 1.30g/cm³. If the density is too low or too high, it may affect the performance of the battery.

Activation method

1. ** Full Filling and Discharging Repair method ** :

- ** Principle ** : By conducting a complete charging and discharging process on the battery, the deep active substances inside the battery are activated, restoring some of their activity and thereby increasing the battery capacity. For lead-acid batteries with mild sulfation and high internal resistance, the full charge discharge repair method is relatively suitable. First, fully charge the battery, and then perform a complete discharge. Each battery should be fully discharged separately. Repeat this process of full charging and complete discharge 1-2 times. This process is like giving the battery a thorough cleaning inside, which can effectively activate the active substances and increase the battery's capacity.

- ** Operation Steps ** : First, charge the battery with a charger that matches the battery specifications. During the charging process, closely monitor the status of the charger and the battery temperature to ensure that the charging voltage and current are stable within an appropriate range and avoid overcharging. When the charger shows that the battery is fully charged, continue charging for 1 to 2 hours to ensure the battery is completely charged. Then, connect the fully charged battery to a suitable load for discharge. During the discharge process, monitor the battery voltage as well. Stop discharging when the voltage drops close to the battery's terminal voltage. Repeat the above charging and discharging process 1-2 times.

- ** Precautions ** : This method should not be used too frequently. At most, it should be used once every three months; otherwise, it may cause damage to the battery. The discharge should be thorough. Each battery needs to be fully discharged independently, and the safety and stability of the discharge equipment must be ensured.

2. ** Method of Adding active agents ** :

- ** Principle ** : Specific active agents are added to the battery. These active agents can participate in the chemical reactions inside the battery, improve the chemical environment inside the battery, reduce the degree of sulfation of the plates, promote the dissolution and transformation of lead sulfate, and thereby restore the battery capacity.

- ** Operating steps ** : First, open the exhaust valve of the battery. Use a syringe to carefully inject an appropriate amount of active agent or distilled water into each individual battery cell. After injection, seal the exhaust valve well and let the battery stand for a period of time to allow the active agent to mix thoroughly with the electrolyte. Subsequently, perform normal charge and discharge operations on the battery. After several charge and discharge cycles, open the exhaust valve, pour out the liquid inside the battery, and then add a slightly denser acid solution to bring the solution inside the battery to the concentration of a standard solution. Finally, conduct a charge and discharge test on the battery again. If the capacity can be restored to over 80%, the repair is successful.

- ** Precautions ** : When adding active agents, strictly follow the prescribed dosage to avoid excessive addition causing damage to the battery. During the operation, pay attention to safety to prevent the active agent from splashing onto the skin or eyes.

3. Pulse Repair Method:

- ** Principle ** : The battery is charged and discharged multiple times by using the pulse current generated by a dedicated pulse repair instrument. Pulsed current can generate a momentary high voltage. Through negative resistance penetration, the lead sulfate crystals on the plates are broken, and they are reconverted into active substances that can participate in electrochemical reactions, thereby eliminating sulfation and restoring battery performance. There are two ways of pulse repair.

- ** Operating Steps ** : Correctly connect the positive and negative terminals of the pulse repair instrument to those of the battery, ensuring a secure connection. Set appropriate pulse parameters, such as pulse frequency, pulse width, and pulse voltage, based on the battery's specifications and vulcanization degree. Start the pulse repair instrument and begin to repair the battery. During the repair process, closely monitor the working status of the instrument and the temperature changes of the battery to prevent the battery from overheating. After the repair is completed, charge the battery with the charger and then conduct a discharge test to observe the recovery of the battery capacity.

- ** Precautions ** : The operation methods and parameter Settings of different pulse repair instruments may vary. It is essential to strictly follow the instrument's user manual for operation. Although high-voltage and high-current pulse charging has a fast repair speed, it has a certain impact on battery life and should be used with caution. Although high-frequency low-current pulse repair has a good effect, the repair time is relatively long and patience is needed.