Smart battery technology is one of the crucial enablers for clean transportation. To grow the acceptance of battery electric vehicles (BEV), driving range, safety hazards and vehicle lifetime are among the key buying criteria of the end-user. All of those criteria are directly influenced by the battery.
One of the main challenges in battery development is the battery thermal management system (BTMS). Keeping the battery at a comfortable temperature is significant in terms of performance, charging capability and lifetime. The overall performance of traction batteries deteriorates significantly at low temperatures due to the reduced electrochemical reaction rate and accelerated health degradation, such as lithium plating. Therefore, battery warm-up/preheating is of particular importance when operating electric vehicles in cold geographical regions.
There are several possibilities to heat a vehicles traction battery, such as convective or conductive heating on cell, module and pack level, as well as internal heating that is applied on a cell level rather.
Convective heating (or indirect heating) describes the mechanism to heat the battery through a fluid, typically air or coolant, using electrical heaters or even heat generated by the vehicle powertrain. Before and after a cold-start, only electrical heating is useful as the powertrain does not reject any waste heat yet. The proper way to engineer such an indirect heating system depends on the general battery thermal management architecture, e.g. if the battery is conditioned via a coolant plate, if immersion cooling is applied or if direct evaporation of refrigerant into a cooling plate is used.
Conductive heating (or direct heating) refers to placing the electric heaters or heating plates containing electric heating wires at the surface of battery cells. Typically, wire resistance heaters are used as heat source that are integrated into cooling plates of packs or modules.
In batter heating, ATT can support both the indirect and direct heating technology
via the coolant is possible using either our state of the art HV coolant heater (LINK einfügen) or customer specific solutions in case of an immersion cooling strategy. ATT’s highly efficient and compact electric PTC coolant heater for rapid fluid heating is suitable for high voltage battery heating concepts and provides several advantages:
- Very high heating power – up to 15 kW
- Voltages 250V – 450V
- Patented spiral-shaped flowpath, superior efficiency compared to classic water heaters
- Low weight – approx. 900g
- Low package space
- 2 heating circuits for optimized power distribution
- Safety through self-regulation and internal heater power monitoring
- Integrated ECU with CAN bus interface
- Precise power regulation (target temperature and power limit)
- Precise coolant temperature sensing (inlet and outlet sensor)
of the battery can be implemented using ATT’s ultrathin and flexible PTC-heating films that can be applied either at the cooling plate or directly at the battery wall. Due to the strong PTC effect of our solution, a maximum temperature threshold to heat battery cells can be specified to prevent the cells from overheating.
Battery wall heating:
Ultrathin and lightweight heating film for integration between battery cells, particularly suitable for pouch cells.
- Geometry: 165 mm x 125 mm (any geometry possible)
- Voltage: 50V (NV/HV and AC/DC possible)
- Steady state heating power: 40 W per heating foil (specific heating power up to 350 kW/m²)
- Heating polymer with strong PTC effect, self-regulating at e.g. 45°C
- Very flexible in terms of shape
Battery bottom heating:
Heating element for application on HV battery cooling plate (rigid or flexible) with integrated temperature sensor. The system enables the battery to reach operating temperature in an accelerated way and supports basic and boost heating function.
- Small package space, low weight
- Positioning between cooling plate and battery cells enable maximum heating efficiency
- High power density (up to 350 kW/m² in boost mode)
- Thermally stable due to strong PTC effect – no risk of thermal runaway
- Intelligent control system
- Practically no influence on effectiveness of cooling system
How to work together with us?
ATT is your ideal partner to realize BEV battery heating solutions from pre-development to serial development and production. Due to our deep understanding of battery thermal management systems, we consider ourself as more than just another supplier of heating systems. We understand the challenge, want to discuss the application with our customers and are known for innovative ideas. We therefor prefer to be involved in an early stage of development to be able to bring in our know-how and experience from 15+ years of thermal engineering for batteries.
Please feel free to contact us with your requirement, idea or ready-made RFQ.