New energy buses (public buses, passenger buses, tourist buses, etc.), as commercially operated vehicles, possess core characteristics such as large battery capacity, distributed battery pack layout, high fast-charging requirements, outdoor all-condition operation, and high passenger capacity. Their Battery Thermal Management System (BTMS) is not simply a "battery temperature control device," but a core system ensuring bus operational safety, battery life, operational efficiency, and range stability. It is also a key module that distinguishes the thermal management of new energy buses from that of passenger cars.
This system, designed for the operating characteristics of bus power batteries (mostly lithium iron phosphate, with a small amount of ternary lithium), uses functions such as active temperature control, waste heat recovery, uniform temperature regulation, and fast-charging temperature control to stabilize the battery pack temperature within the optimal operating range of 25~35℃. It also meets the mandatory safety standards of the national standard "Safety Requirements for Power Batteries for Electric Vehicles" (GB 38031), making it an essential core system for the commercial operation of new energy buses.
I. Core Application Value of BTMS for New Energy Buses
Compared to passenger vehicles, BTMS for electric vehicles（buses） buses focuses more on **"operation-oriented, with core values centered around reducing operating costs, improving operating efficiency, and ensuring operational safety, rather than simply increasing range. This is the core difference between thermal management in buses and passenger vehicles:
1. Preventing Thermal Runaway and Ensuring Vehicle Operational Safety
New energy bus battery packs typically have capacities of 100-300kWh, composed of dozens of battery modules connected in series and parallel. Outdoor exposure, high loads during uphill driving, and high current during fast charging can easily lead to localized overheating. battery thermal management system, through active cooling, temperature monitoring, and thermal runaway warnings, prevents battery bulging, short circuits, and thermal runaway, fundamentally reducing the accident rate in bus operations (the safety requirements for buses/passenger vehicles are far higher than for passenger vehicles).
2. Extending Battery Cycle Life and Reducing Operational Replacement Costs
The power battery is the core cost of new energy buses (accounting for 30%-40%), and the battery life of the operating vehicle directly determines the total life cycle cost of a single vehicle. For every 1°C increase in temperature, the cycle life of a lithium battery decreases by approximately 2%; charging and discharging at low temperatures can lead to irreversible lithium crystallization electric vehicle thermal management, through precise temperature control, can extend the cycle life of bus batteries from 3-4 years (approximately 2000 cycles) to 5-6 years (approximately 3000 cycles), significantly reducing battery replacement costs for operators.
Adapting to fast charging conditions improves bus operational turnover. Buses often use a 3-10 minute fast charging mode (fast charging current can reach 300-500A). High-current charging quickly generates a large amount of heat. If not cooled in time, the battery will trigger overheat protection and reduce charging power, resulting in longer charging times. BTMS's dedicated fast-charging temperature control function can quickly control the battery temperature within the optimal range, avoiding charging power degradation and ensuring the "charge and go" operational rhythm of buses.
3. Stabilizing battery charging and discharging efficiency reduces operational range degradation. New energy buses operate on fixed routes (buses) or long distances (passenger transport), requiring high range stability. High temperatures reduce battery discharge efficiency, while low temperatures can cause a 30%–50% capacity reduction. BTMS (Battery Thermal Management System) stabilizes battery charge/discharge efficiency above 90% through active cooling at high temperatures and active preheating at low temperatures, preventing power loss and breakdowns due to battery temperature issues during operation.
Improving battery pack temperature uniformity prevents premature degradation of individual modules. Battery packs in new energy buses are often distributed (roof, chassis sides, rear). Battery modules in different locations are greatly affected by ambient temperature (e.g., roof modules exposed to high temperatures, chassis modules at low temperatures), easily leading to excessive temperature differences (>5℃) between modules, causing overcharging, over-discharging, and premature degradation of individual modules. BTMS, through temperature uniformity regulation, controls the temperature difference between modules within the battery pack to **≤3℃**, ensuring overall battery pack consistency and preventing "single module dragging down the entire pack." 4. Energy saving and consumption reduction, reducing operating power consumption. High-quality BTMS will combine the waste heat recovery of bus motor, electronic control and air conditioning system to replace traditional PTC electric heating (power consumption can reach 10~20kW), reduce battery preheating energy consumption at low temperature, increase bus operating range by 15%~20% in winter, and reduce charging frequency and operating power consumption costs.
Post time: Jan-26-2026
