Liqui Moly has developed a brake fluid specially for vehicles with electric propulstion, including hybrid and battery-electric vehicles.
Specific electric vehicle brake fluid is key, as there are a number of properties that standard products cannot fulfil, or are too dangerous to allow their safe use. With this in mind, Liqui Moly have developed DOT 5.1 EV.
All vehicles have a braking system, and they all require their fluid to be changed every two years. However, the requirement profile for electric vehicles is sometimes completely different, often more demanding.
One thing an electric vehicle brake fluid needs to offer is corrosion protection. “Because the electric motor also acts as a brake and uses it to generate energy for the battery, the mechanical brake system is used less frequently. This leads to spot corrosion,” comments David Kaiser, Head of Research & Development at Liqui Moly.
“However, this does not mean that a brake system in an electric vehicle does only a little work. These vehicles are generally heavier than vehicles that are powered by an internal combustion engine and rapidly reach high speeds from which they also have to be braked abruptly in the event of danger. As a result, the brakes quickly become very hot.”
Therefore, an electric vehicle brake fluid, like the one Liqui Moly has developed, has to be effective when the brake system is hot, and therefore requires a high dry and high wet boiling point.
Low conductivity key in electric vehicle brake fluid
Any fluid used in an electric vehicle has to feature the lowest possible electrical conductivity, brake fluid included. This plays a role if an electrical system is installed near the brake system and is not sufficiently shielded. As with the wireless, inductive charging of an electric toothbrush or mobile phone, electrical voltages can then be induced in the brake system, which can decompose the brake fluid or promote corrosion.
The fourth property of interest is viscosity. “As with motor oil, the flow behaviour is decisive for the performance of the fluid. The lower the viscosity, the faster the engine is fully oiled. A low-viscosity brake fluid transmits the braking pulses in the system more quickly, the electronic driver assistance systems such as ABS or ESC function better and respond even more sensitively,” Kaiser points out.
Liqui Moly adds that when it comes to brake fluids, the same applies as oils: Only use what should be used.