The RM3 CTMS provides OEMs with a powerful, integrated thermal management platform for electric buses and coaches requiring strong performance in high-ambient environments.

Its reversible heat pump delivers efficient heating and air conditioning, while active and optional passive battery cooling maintain pack stability across diverse duty cycles. Additional coolant loops can also be configured to manage traction motors and power electronics temperatures for a complete thermal solution.

With ducted passenger heating and air conditioning, a dedicated driver AC take-off, and low GWP refrigerant (R454C), the RM3 CTMS is compatible with the latest high voltage vehicle architectures (540 – 900V DC).

The system is powered by Grayson’s proprietary CAN-based automatic thermal control software and Intelligent Thermal Controller, which dynamically regulates multiple subsystems for precise temperature control.

These features are designed to support reliable performance no matter the environment.

• Complete Multi-Loop Integration: Combines battery thermal management, driver/passenger HVAC, and power electronics cooling within a single intelligent module.
• Reversible Heat Pump for Heating & AC: Efficient thermal control across HVAC, battery, and powertrain systems.
• Battery Thermal Management Modes: Maintains stable battery temperatures in varied duty cycles via heating and active cooling as standard, and optional passive cooling.
• Grayson Intelligent Thermal Controller: Developed and validated by Grayson for precision regulation.
• Optional Coolant Loops for Power Electronics & Traction Motors: Protects critical drivetrain components from overheating.
• Passive Cooling Options & Heat-Pump Efficiency: Lower energy consumption during mild ambient conditions.
• High-Capacity Heating with External PTC Option: Ensures heat availability in low-ambient operation.
• CAN J1939 Communication: Seamless integration with pumps, heaters, and sensors.
• Dynamic Control Software: Continuously adjusts operation to match vehicle thermal demands.
• High-Voltage Compatibility: up to 900V DC, meeting the needs of next-generation electric platforms.
• Low-GWP Refrigerant Option: R454C compatibility, supporting reduced environmental impact and sustainable operation.
• Flexible for Global Markets: Suitable for 8 m – 24 m bus lengths and LHD/RHD compatible.

Every technical element plays a role in delivering reliable and predictable system performance.

• Nominal Cooling Capacity: 34kW @ 40°C
• Maximum Cooling Capacity: 37kW @ 40°C
• Nominal Heating Capacity (Heat Pump): 28kW @ 0°C
• Maximum Heating Capacity (Heat Pump): 38kW
• Operating Temperature: -20°C to +45°C
• High Voltage Range: 540–900V DC (Nominal 800V)
• Low Voltage Range: 18–32V DC (Nominal 28V)
• Refrigerant: R454C
• Dimensions (L × W × H): 2800 × 2000 × 365 mm
• Weight: 300 kg
• Communication: CAN protocol: J1939
• Ingress protection: IP67 (controller box)