High-voltage performance
Eberspächer develops heating systems for 800-volt vehicle electrical systems designed for battery conditioning and cabin temperature control in electric vehicles. In this interview, Dr. Karsten Bolz, Head of Technology and Innovation in the Electrical Heaters Business Unit, explains the technological background and advantages of the new solutions.
The two new heating solutions for 800-volt-systems ensure interior comfort and quickly bring the battery up to its optimal temperature range.
Dr. Karsten Bolz, Head of Technology and Innovation in the Electrical Heaters Business Unit
Thermal management is considered one of the keys to successful electric mobility. Why?
14 April 2026 – Thermal management influences three key factors: range, charging performance, and comfort. Extreme temperatures can significantly reduce battery performance and thus limit range. At the same time, batteries charge much faster at optimal temperatures. And last but not least, comfort also plays an important role. Reliable temperature control is crucial for the driver, especially in cold conditions.
Thermal management is therefore not just a “nice-to-have.” That’s why the Business Unit recently developed two new heating solutions for 800-volt systems. How do they differ?
We developed a coolant heater and an air heater that perform different functions within the vehicle and are specifically tailored to the requirements of modern electric vehicles. The coolant heater warms the coolant circuit and brings the battery quickly to its optimal temperature range. It is based on a thick film element.
The air heater, on the other hand, is designed to enhance passenger comfort. The product allows for separate temperature control in up to four zones, such as the driver and passenger sides or additional areas in larger vehicle interiors. This enables heat to be distributed according to need and optimizes energy usage. It utilizes PTC technology, which is characterized by its self-regulating properties and ensures safe and efficient operation.
What advantages does the thick film design offer in coolant heaters compared to conventional PTC solutions?
The thick film element is based on a screen-printing process in which conductive structures are applied directly to a metal plate. This allows us to achieve very compact designs while delivering high power output. As a result, we can provide heating capacities of up to 12 kW within the installation space and cost constraints specified by our customers. At the same time, the design meets the typical packaging requirements of modern vehicle platforms.
The coolant heater is patented. What sets this solution apart?
A key advantage lies in the optimized coolant flow within the system. This ensures even temperature distribution and prevents the formation of hot spots, thereby avoiding overheating of the heater.
In addition, the heater is equipped with several sensors that continuously monitor relevant operating parameters, as well as an independently operating second shutdown path. As soon as values fall outside the defined operating window, the system is automatically switched to a safe state.
This multi-stage safety concept is particularly important in the commercial vehicle sector. Since these vehicles are often used as sleeping quarters or living spaces, significantly stricter requirements apply than in the passenger car sector.
Instead, the air heater uses PTC technology. Why?
Because PTC is particularly well-suited for use in the passenger compartment, since the air heater is positioned very close to the passenger and is sometimes even installed inside the bulkhead – the partition between the engine compartment and the passenger compartment.
It is based on a ceramic semiconductor whose electrical resistance increases as the temperature rises. At low temperatures, current can flow almost unimpeded, causing the heating element to heat up quickly and provide high heating output. Once the desired temperature is reached, the resistance increases significantly. The current flow is reduced, and the heating output adjusts automatically, reliably preventing overheating.
Thermal management thus goes far beyond mere cabin heating and has a significant impact on range and charging time. Do the solutions cover both areas?
Both systems complement each other perfectly in their functions and specifically address key requirements within the vehicle. While the coolant heater handles battery conditioning – thereby significantly contributing to the battery’s efficiency, charging performance, and service life – the air heater ensures a comfortable interior climate that can be adjusted as needed.
And looking ahead: What developments and trends will shape thermal management in the future?
Thermal management is becoming more complex. New battery technologies, natural refrigerants, and heat pumps require closely integrated cooling and heating circuits. The focus is shifting from individual components to holistic system solutions.
Against this backdrop, we are developing the Integrated Thermal Management System (ITMS). It bundles key functions into a compact, modular unit and enables efficient, intelligent control of all thermal processes in the vehicle.