Winter in cold regions presents rigorous challenges to various systems of commercial vehicles. Low temperatures can make materials brittle, slow down electrochemical reactions, and thicken lubricants, directly affecting vehicle starting performance, driving stability, and overall reliability. In cold regions, especially during winter, it is essential to plan ahead and strictly implement winter maintenance strategies for commercial vehicles to ensure safe and efficient operation. This article focuses on the technical details of battery management and fuel system anti-freezing measures.
Under extremely low temperatures, the chemical reaction rate of both traditional lead-acid batteries and new energy power batteries decreases significantly. For lead-acid batteries, low temperatures cause a significant reduction in battery capacity and starting current, possibly only about half of that at normal temperatures, directly leading to difficulties in cold starting or complete failure to start. For power batteries (such as lithium-ion batteries in electric commercial vehicles), the viscosity of the electrolyte increases, internal resistance increases, and discharge efficiency decreases significantly, resulting in reduced range. Maintenance should start with the basic condition of the battery:
Checking and Cleaning Connection Ports:
If battery terminals, connectors, and connecting wires are covered with frost, snow, or salt deposits, a high-impedance electrical connection will form. This limits the starting current, making low-temperature starting more difficult. Therefore, regularly cleaning the battery terminals and ensuring secure connections is essential.
Temperature Monitoring and Condition Assessment:
Monitor the battery voltage, current, and state of charge (SOC), especially before and after starting in extremely low temperatures. Using the on-board diagnostic system (OBD) to check the battery health helps identify potential degradation.
Power-Off Strategy for Long-Term Parking:
If the vehicle needs to be parked for a long time (several days or more), it is recommended to disconnect the negative terminal of the battery to prevent self-discharge and avoid excessive power loss that could lead to starting difficulties.
In winter, batteries require more proactive insulation and maintenance. For commercial vehicles, equipping a low-temperature thermal management system can significantly improve battery performance. Such systems use fuel-fired parking heaters, PTC electric heaters, and other methods to heat and insulate the battery, effectively maintaining the battery within a suitable operating temperature range, thereby improving starting and range performance.
2.1 Lead-Acid Battery Maintenance Essentials
Capacity Degradation Control: For every 1°C decrease in temperature, the available capacity decreases by approximately 0.8%. At -10°C, the actual available capacity of a 60Ah battery is only about 48Ah, and the starting current (CCA) drops by over 40%.
Charging Management:
Avoid deep discharge; recharging is necessary when the SOC is below 30%;
The charging environment temperature should be above 5°C; prioritize charging indoors or in a heated garage;
In winter, charging time can be extended to 10–12 hours to avoid plate sulfation caused by fast charging.
Wiring Maintenance: Check the terminals monthly for white oxides (lead sulfate crystals). Clean with a 10% baking soda solution, then apply a special battery protective paste or petroleum jelly to prevent corrosion.
Long-Term Storage: If the vehicle is parked for more than 7 days, disconnect the negative terminal or use a smart maintenance charger to maintain the SOC between 50% and 70% to prevent plate sulfation.
2.2 Lithium-Ion Battery (Lithium-ion/Methanol-Hydrogen Electric) Maintenance Essentials
Charging Strategy:
Optimal Time: Charge immediately after operation, utilizing residual heat to improve charging efficiency;
Preheating Activation: Remotely activate the battery preheating function through the vehicle's app (e.g., Yutong, BYD models) to raise the battery temperature to above 15°C, which can increase fast charging power by more than 3 times;
SOC Range: In winter, it is recommended to maintain the SOC between 20% and 80%, avoiding full charge or complete discharge to extend cycle life.
Charging Environment: Prioritize underground garages or indoor charging stations. Install anti-freeze covers on the charging port to prevent freezing that could prevent the plug from being removed.
Balancing Maintenance: Perform a complete 0%-100% charge and discharge cycle at least once a month to trigger BMS cell balancing and prevent the accumulation of voltage deviations.
Note: Methanol-hydrogen electric buses can still maintain a range of over 600km in a -25°C environment. Their methanol engine can continuously provide heat to the battery system, significantly reducing thermal management energy consumption.
For fuel-powered commercial buses, especially in cold regions during winter, the fuel system is just as critical as the battery. Diesel fuel is prone to gelling at low temperatures, leading to a significant increase in fuel viscosity and even clogging of pipes and filters, resulting in poor fuel supply, difficulty starting, and even engine stalling.
In addition, water in the fuel tank can form ice crystals inside the fuel system, further blocking small passages.
Selecting low pour point fuel and adding antifreeze: In winter, diesel fuel with a pour point significantly lower than the ambient temperature should be used. In extremely cold conditions, add an anti-gelling agent or a professional winter fuel additive to effectively inhibit fuel waxing and solidification.
3.1 Diesel Fuel Grade Selection
|
Temperature range |
Recommended diesel grade |
Pour point requirements |
|
-5℃to 0℃ |
0# diesel |
≤0℃ |
|
-10℃to -5℃ |
-10# diesel |
≤-10℃ |
|
-20℃to -10℃ |
-20# diesel |
≤-20℃ |
|
-30℃or less |
-35# or -50# |
≤-35℃or -50℃ |
In actual operation, it is recommended to change the fuel grade 3-5 days in advance based on local weather forecasts to avoid filter clogging caused by last-minute fuel changes.
3.2 Fuel Heating System Configuration
Fuel heater: It is recommended to install an electric or engine waste heat fuel heating device, with the heating temperature controlled at 15℃–25℃ to prevent wax crystal precipitation.
Filter insulation: Install an insulation cover on the fuel filter. Some models are equipped with heated filter elements, which can effectively delay clogging.
Antifreeze additive:
Use a diesel anti-gelling agent that meets the GB/T 23804 standard, with an addition ratio of 1:1000–1:2000 (volume ratio);
It is strictly prohibited to dilute with alcohol or gasoline to avoid damaging fuel system seals.
3.3 Filter Maintenance Cycle
Replace the fuel filter every 15,000 km or before winter;
Check the filter pressure difference indicator weekly. If the warning light comes on, replace it immediately;
Replacement should be performed in a warm garage to avoid wax crystal clogging the new filter element due to low temperatures during disassembly.
|
Step |
Operation content |
Precautions |
|
1 |
Pre-start checks |
Confirm that the battery voltage is ≥12.6V (lead-acid) or the BMS displays "Startable"; check if the fuel heater is working properly. |
|
2 |
Preheating Steering System |
For pure electric/hybrid vehicles, release the handbrake and gently turn the steering wheel while stationary for 20 minutes to warm up the power steering fluid and reduce the load on the power steering pump. |
|
3 |
Start the engine |
Each attempt to start should not exceed 5 seconds, with intervals of at least 15 seconds. If the engine fails to start after 3 attempts, the fuel system or battery status should be checked. |
|
4 |
Warm-up operation |
After starting, let it idle for 3-5 minutes until the water temperature reaches above 60°Cbefore starting to drive, to avoid cold start wear. |
|
5 |
System self-test |
Observe whether the "AIR DRYER" yellow light on the dashboard is lit (this indicates that the dryer is in normal heating mode). |
|
Challenge |
status quo |
suggestion |
|
Risks of low-temperature fast charging of lithium batteries |
Fast charging in extremely cold conditions can easily lead to lithium plating, posing a safety hazard. |
Promote the "preheating + slow charging" strategy and prohibit the use of fast charging below -15°C. |
|
Fuel-fired heaters have high energy consumption. |
Electric heaters account for 15%–20% of the vehicle's total energy consumption. |
Promote engine waste heat recovery heating systems |
|
Inconsistent maintenance standards |
There is no unified winter maintenance manual among different brands. |
It is recommended that industry associations take the lead in formulating the "Winter Maintenance Standards for Commercial Passenger Vehicles in Cold Regions". |
Winter vehicle maintenance is not limited to a single system, but is a comprehensive engineering project covering power, fuel, lubrication, and thermal management. Commercial passenger buses operating in cold regions must develop and strictly implement a winter maintenance plan in advance:
Battery management should encompass a comprehensive approach from cleaning and monitoring to insulation and preheating; the fuel system should address every aspect, from fuel selection and water removal to filter maintenance and thermal management measures.
For every cold start and operation, "prevention is better than cure" should be the guiding principle for engineers. During the long, harsh winter season, a systematic and standardized winter maintenance strategy is the true foundation for ensuring the safe operation of commercial passenger buses.
