Under the skin: why coolants are essential to improving electric vehicles Car News

Electric vehicles have shaken the world in more ways than one: Technology has changed, so have production methods, driving styles, fueling, tire design and just about anything you can think of. Deeper below the surface other changes are underway, and one of them is the design of the fluids that keep engines, engines and transmissions alive.

In a conventional car, a mixture of water and glycol (antifreeze) cools the engine while a variety of oils formulated for each particular task lubricates the engine, axles and transmission and, in some cases, performs a second. cooling work.

Electric vehicles are a different kettle. With combustion out of the equation, there are no combustion products for the oil to worry about and no extremely high temperature hot spots like combustion chambers. EV transmissions always need to be lubricated and engines always need to be cooled, as do batteries and power electronics. In fact, they need more than just cooling: they need finely tuned thermal management not only to protect them, but also to extract maximum efficiency from them. This is an area that oil companies are increasingly focusing on as a source of business as the ICE wears off.

Petronas Lubricants International is one of those developing fluids dedicated to EVs (called the Iona range). He believes it can improve efficiency, with the ripple effect of increasing range, simply by using lubricants and coolants specially developed for electric vehicles. Thermal management changes from indirect cooling of electrical and electronic components to direct cooling. With indirect cooling, heat sinks (usually just alloy plates) suck heat from a machine, inverter, or battery cells and transfer it to the coolant pumped through the system as usual.

This is inefficient, as only part of the heat is removed by the heat sinks and coolant; the rest must escape. With direct cooling, the fluid comes into direct contact with electrical components such as printed circuits, as well as gaskets and copper and plastic components; and for this to happen without causing a massive short circuit, the fluid must be dielectric (unable to conduct electricity). The story becomes more complicated as EV transmissions are integrated rather than separate. Next, the fluid must both lubricate the gears and directly cool the motor and its electronic components.

Ultra-fast charging could be made even faster if the cooling of the battery and charging equipment could also be improved. The charge rate of cars capable of charging 350 kW (the Porsche Taycan and Hyundai Ioniq 5, for example) peaks early and then gradually declines as the battery management systems ‘choke’ the current to prevent damage. Petronas points out that the Taycan takes 41 minutes to recharge when empty, but if it were able to charge at 350 kW until fully charged, it could become 16 minutes. That’s not to say it’s necessarily achievable, but it does say that there is huge scope for improving charge times there by focusing on cooling and the fluids that do it. It looks like the next 10 years will be a busy time for chemists, and more than just an improvement in battery technology.