Deeply devoted to heavy-duty travel: full analysis of truck lead-acid batteries (structure, faults, maintenance and selection)

Among the tens of thousands of parts in a truck, the lead-acid battery may seem inconspicuous, but it is the "energy heart" that ensures the normal operation of the vehicle. It not only provides strong instant power for engine starting, but is also the core power supply source for on-board electrical equipment. It can also store the electric energy generated by the generator and protect the electrical equipment from voltage fluctuations, which is directly related to the truck's attendance rate and driving safety. Whether it is heavy-duty transportation on long-distance trunk lines or frequent starts and stops in urban distribution, truck lead-acid batteries are silently carrying heavy tasks. This article will comprehensively dismantle the core knowledge of truck lead-acid batteries from the four dimensions of structural principles, common faults, scientific maintenance, and selection skills, helping truck owners avoid faults, extend service life, and reduce vehicle costs.
1. Core structure and working principle: Understand the "energy logic" of lead-acid batteries

Compared with ordinary civilian lead-acid batteries, truck-specific lead-acid batteries focus more on resistance to vibration, high-current discharge, and resistance to harsh environments. Its structural design and working principle are optimized around heavy-duty travel needs. The core details are as follows:

(1) Core structure

Truck lead-acid batteries are mainly composed of seven core components: positive plate, negative plate, electrolyte, separator, battery tank, pole, and liquid injection cover (or sealing cover). Each component works together to ensure stable power supply:

- Plate: The positive plate is made of lead and covered with lead dioxide, and the negative plate is made of lead. The thickness and material of the plate directly determine the discharge capacity and service life of the battery - truck-specific lead-acid batteries mostly use thickened alloy plates, and some high-end models also use radial ribs and small grid designs to improve low-temperature starting performance and charging acceptance.

- Electrolyte: The main component is sulfuric acid aqueous solution, which is the "medium" for the conversion of electrical energy and chemical energy. Its concentration and liquid level directly affect the battery capacity and need to be checked and replenished regularly (except for maintenance-free models).

- Separator: Made of insulating material, its main function is to isolate the positive and negative plates, prevent short circuits, and allow electrolyte penetration and gas circulation. The separators of truck batteries mostly adopt high-density acid-proof design, and some also use special Jiqun melt glue technology to tightly fix the Jiqun and the tank body, enhance vibration resistance, and adapt to the bumpy driving conditions of trucks.

- Other components: The battery tank is made of flame-retardant and impact-resistant materials to prevent electrolyte leakage and shell damage; the poles are conductive cores and need to be sealed and protected to avoid corrosion; the liquid filling cover (ordinary model) has a vent to discharge gas generated during charging and prevent excessive internal pressure.

(2) Working principle

The core of the truck lead-acid battery is a "reversible chemical reaction", which realizes charging and discharging cycles through the mutual conversion of electrical energy and chemical energy. Its core chemical reaction formula is: $$PbO_2 + 2H_2SO_4 + Pb \leftrightarrow[charge][discharge] 2PbSO_4 + 2H_2O$$.

- Discharge process: When the truck is started or on-board electrical appliances are used, a chemical reaction occurs inside the battery. The lead dioxide in the positive plate and the lead in the negative plate react with the sulfuric acid in the electrolyte to generate lead sulfate and water. At the same time, chemical energy is released and converted into electrical energy to power the engine starter, lights, air conditioners and other equipment.

- Charging process: After the engine is started, the generator starts working, converting mechanical energy into electrical energy to charge the battery; at this time, the chemical reaction proceeds in reverse, lead sulfate is decomposed into lead dioxide, lead and sulfuric acid, and the electrical energy is converted back into chemical energy and stored until the battery is fully charged.

It is worth noting that in the later stages of charging (when the battery reaches more than 80%), oxygen and hydrogen will be produced inside the battery. If the vent hole is blocked and the gas cannot be discharged, the internal pressure will increase. In severe cases, the shell may bulge or even explode. This is also one of the key points of subsequent maintenance.

2. Three common faults + solutions: a must-read emergency guide for card lovers

When trucks drive for a long time under complex working conditions such as bumps, high temperatures, and low temperatures, lead-acid batteries are prone to various types of failures. Among them, bulging of the shell, corrosion of joints, and capacity decline (fast discharge) are the three most common ones. Most failures can be solved through simple operations without directly replacing the battery. The details are as follows:

(1) Fault 1: Shell deformation and bulging

This is a high-risk failure of truck lead-acid batteries, which is mostly caused by excessive internal temperature and excessive pressure. There are three core causes: First, the voltage is too high and the charging time is too long, resulting in overcharging and accelerating gas production; second, the battery loses too much water, the heat capacity decreases, and the temperature rises rapidly (over 80°C) during charging; third, the vent holes are blocked, gas cannot be discharged, and the internal pressure soars.

Solutions and Prevention:

- Emergency treatment: If you find a slight bulge in the casing, stop charging immediately, check whether the ventilation holes are blocked, clean up debris to ensure smooth ventilation, and wait to see if it recovers after cooling. If the bulge is severe, the casing cracks, or there is electrolyte leakage, the battery needs to be replaced immediately to avoid explosion or corrosion of vehicle parts.

- Daily prevention: Clean the vents regularly to avoid clogging; when the battery loses too much water, add distilled water as required (no tap water or concentrated sulfuric acid is allowed); control the voltage and duration when charging, and choose a charger that matches the battery to avoid overcharging; reduce the use of high-power appliances such as parking air conditioners in high-temperature environments to reduce battery load.

(2) Fault 2: Connector corrosion

It manifests itself as a white or yellow powdery substance appearing around the battery poles and connectors. The core components are lead sulfate and iron sulfate, which are mostly generated by the electrolyte splashing and chemical reaction with the poles and wire clips. This type of material has extremely poor conductivity, which will increase the contact resistance, causing the battery output current to decrease, which will lead to problems such as weak starting and abnormal operation of vehicle electrical appliances.

Solutions and Prevention:

- Emergency treatment: Turn off the power of the vehicle, rinse the corroded area with clean water, and thoroughly clean up the powder; then wipe it with a rag soaked in 10% soda water to neutralize the remaining acidic substances, and finally dry it with a dry rag. Apply butter or Vaseline on the surface of the pole and connector to isolate air and electrolyte to prevent further corrosion.

- Daily prevention: Check the battery seal regularly to avoid electrolyte splashing; when installing the battery, ensure that the joints are firmly fixed to reduce seal loosening caused by vibration; every time you maintain the vehicle, check the joints for signs of corrosion and clean and protect them in time.

(3) Fault 3: Decreased capacity and rapid discharge

After being fully charged, the number of starts is reduced, and the battery is quickly depleted when using electrical appliances while the car is parked. The core causes include plate vulcanization, severe self-discharge, insufficient electrolyte, and battery aging. Among them, plate vulcanization is the most common cause - when the battery is stored uncharged or over-discharged for a long time, the active material on the plate will crystallize into irreversible lead sulfate crystals, which hinders current conduction and leads to a decrease in capacity.

Solutions and Prevention:

- Emergency treatment: If it is mild plate vulcanization, you can use the "full, full, discharge" method to activate - use a matching charger to fully charge the battery, and then drain the power through an external load (such as a car headlight). Repeat the cycle 1-2 times to restore part of the capacity; if the electrolyte is insufficient, add distilled water and let it sit for 2-3 hours, then charge with a low current for 8-12 hours; if the capacity drops by more than 30% and the battery life exceeds 3 years, it is recommended to replace the battery.

- Daily prevention: Avoid long-term battery loss. When parking for a long time (more than 3 days), start the vehicle to idle for 30 minutes every 5 days, or disconnect the battery negative terminal to reduce self-discharge; avoid excessive discharge, turn off the on-board electrical appliances promptly after the vehicle is turned off, and do not use high-power equipment such as parking air conditioners to consume power for a long time; regularly check the electrolyte level and replenish distilled water in time.

3. Scientific maintenance skills: extend battery life and reduce vehicle costs

The service life of truck lead-acid batteries is usually 2-4 years. Good maintenance habits can extend the service life by 1-2 years. Taking into account the driving conditions of the truck, the following five maintenance points need to be paid attention to. The operation is simple and the cost is low. Truck owners can practice them daily:

(1) Avoid power loss, the first point of core maintenance

Loss of power is the main cause of vulcanization of battery plates and shortened lifespan, especially for long-distance trucks, which need to be avoided: First, after the vehicle is turned off, be sure to turn off all on-board electrical appliances, including lights, radios, parking air conditioners, etc., to prevent "constant lights" and "long power consumption"; Second, if the vehicle is parked for a long period of time (such as outage and holidays), either start the vehicle and charge it at idle speed for 30 minutes every 3-5 days, or disconnect the negative terminal of the battery to prevent self-discharge and loss of power; third, if you find that the vehicle is unable to start and the lights dim, charge it in time to avoid continuing to drive with a loss of power.

(2) Regular inspections and timely identification of hidden dangers

It is recommended to check once a week and conduct comprehensive maintenance once a month, focusing on three points: first, the electrolyte level, ensure that the liquid level is between the scale lines, and add distilled water in time when it is lower than the scale line; second, check the poles and joints for corrosion, looseness, and clean and fix them in time; third, the battery shell, check whether there are bulges, damage, and electrolyte leakage. If any problems are found, deal with or replace them immediately. In addition, it is recommended to conduct professional testing every six months to measure the battery voltage and capacity through instruments to accurately judge the battery status.

(3) Adapt charging and reject "wrong charging and overcharging"

Improper charging will seriously damage the battery, and the principle of "adaptation and moderation" must be followed: first, choose a charger that matches the battery specifications. Truck lead-acid batteries are mostly 12V or 24V, and the charger voltage must be consistent with the battery to avoid too high or too low voltage; second, control the charging time, generally After the battery is fully charged (the charger indicator light turns green), recharge for 1-2 hours. There is no need to charge for a long time. Third, avoid charging in high and low temperature environments. High temperatures can easily lead to overcharging and bulging. Low temperature charging efficiency is low and it is easy to lose power. Try to charge in a normal temperature environment.

(4) Protection is in place and adaptable to complex working conditions

Trucks drive bumpy and are prone to contact with dust and rainwater, so protection is required: First, the battery must be installed firmly and the fixing brackets must be tightened to reduce plate damage and electrolyte leakage caused by bumps; second, avoid the battery coming into contact with open flames and high-temperature objects, and stay away from flammable and explosive items when charging to prevent gas from exploding in open flames; third, when driving on rainy days, avoid rainwater soaking the battery to prevent short circuits; fourth, clean up dust and debris on the battery surface, keep the surface clean, and avoid dust accumulation leading to poor heat dissipation.

(5) Store it reasonably, and do not "lose maintenance" if left idle.

If the truck is idle for a long time, you need to pay attention to three points when storing the battery: first, fully charge the battery before storage to avoid storage with a loss of power; second, place the battery in a dry, ventilated, and cool environment, away from high temperature, humidity, and direct sunlight; third, check the power every three months. If the voltage is too low, recharge it in time to prevent the plate from being vulcanized.

4. Selection skills: Choose the right battery to adapt to heavy load requirements

There are many types of truck lead-acid batteries on the market. Only by choosing the right battery can you avoid problems such as "insufficient power" and "short lifespan". Focus on four key points. Choose based on your own vehicle type and driving conditions. There is no need to blindly pursue "high prices":

(1) Look at the specifications: match the vehicle voltage and installation space

Truck lead-acid batteries are mainly divided into two specifications: 12V and 24V. Light trucks and micro trucks mostly use 12V batteries, while heavy trucks and tractors mostly use 24V (two 12V batteries connected in series). When selecting, you need to confirm the original battery specifications of the model to avoid voltage mismatch that may cause failure to start or damage to electrical equipment. At the same time, measure the size of the battery installation space and confirm that the length, width, and height of the battery are suitable for the installation location to avoid failure to install or looseness after installation.

(2) Look at the core parameters: cold starting current and reserve capacity

These two parameters directly determine the battery's starting capability and continuous power supply capability, and are the core of model selection:

- Cold cranking current (CCA): refers to the maximum current that the battery can output for 30 seconds in a low-temperature environment (usually -18°C). The higher the value, the stronger the low-temperature starting ability. It is suitable for cold regions in the north or trucks that often start at low temperatures. Truck friends in the north are recommended to choose batteries with CCA ≥ 700A, and batteries with CCA ≥ 500A in southern regions.

- Reserve capacity (RC): refers to the time it takes for the battery to be continuously discharged with a current of 25A until the voltage drops to 10.5V in an environment of 25°C after it is fully charged. The longer the value, the stronger the continuous power supply capability. It is suitable for long-distance trucks that often use high-power appliances such as parking air conditioners and on-board refrigerators. It is recommended to choose a battery with RC ≥ 120 minutes.

(3) Look at the craftsmanship: adapt to heavy load and bumpy working conditions

Trucks drive on bumpy roads for a long time, and the vibration resistance of the battery is very important. When selecting the battery, focus on two points: First, the plate technology, give priority to batteries with thickened alloy plates and using Jiqun melt glue technology. The plates of this type of battery are firmly fixed and are not easy to fall off or be damaged due to bumps; second, the shell material, choose ABS material with good flame retardant, impact resistance, and sealing properties to prevent shell damage and electrolyte leakage. In addition, if the battery is installed at the rear of the truck (where it is subject to more severe vibrations), you can choose a high vibration resistance (HVR) model to adapt to harsh installation environments.

(4) Look at the type: choose ordinary type or maintenance-free type as needed

Truck lead-acid batteries are mainly divided into ordinary water-added type and maintenance-free type. Both have their own advantages and disadvantages. Truck owners can choose according to their needs:

- Ordinary water-adding type: affordable, large capacity, and highly repairable. It is suitable for card users who are cost-conscious and willing to spend time on maintenance. The disadvantage is that it requires regular replenishment of distilled water, cumbersome maintenance, relatively poor sealing, and prone to electrolyte leakage and joint corrosion.

- Maintenance-free type: good sealing, no need to replenish distilled water, simple maintenance, suitable for long-distance trucks and truck owners who do not have time for frequent maintenance. The disadvantage is that the price is slightly higher, it is not repairable, it can only be replaced after failure, and the capacity decay rate is relatively fast.