Urgent need for test methods for electric and hybrid fluids

PETRONAS has joined growing calls for specification development and standardised test procedures to support fluid development for electric and hybrid vehicle applications. Speaking at F+L Week 2023 in Kuala Lumpur, Malaysia, on June 15, Ravi Tallamraju, chief technology officer at PETRONAS Lubricants International Sdn. Bhd. (PLI), outlined an “urgent need” for test methods relating to hardware protection, copper compatibility, electrical properties and thermal management. Tallamraju also stressed the importance of simulation and modelling, without which it is almost impossible to accurately assess performance, he says.

During his presentation, several disruptive challenges associated with the diverse hardware designs were discussed. Tallamraju noted contradictory demands on fluids, as e-motors and inverters inside the transmission require a very delicate balance between electrical, thermal and wear protection capabilities. He emphasised that restrictive physical and chemical parameters can severely limit base fluid and additive choices. The PLI representative also cited a lack of standardised test procedures and suggested existing fluid specification settings are based on limited experience or the few fluids in use, rather than a real technical need. This seriously limits innovative solutions, he says.

PLI is working hard to develop their own test procedures at their global research and technology centre in Turin, Italy.  However, Tallamraju noted the difficulties of such research. Extensive studies by PLI indicate chemical and physical parameters alone don’t indicate true performance. For example, low viscosity fluid alone is not always the best solution, as cooling efficiency depends on the e-motor design, he says. 

Tallamraju outlined the need to gain a better understanding of hardware design variations and how they impact fluid needs. We also need to identify the most critical parameters for e-transmissions and new/standardised testing protocols to assess performance, while avoiding arbitrary physical and chemical limits that seriously limit innovation and base fluid choices, he says.