Connector compatibility: the missing link?
The compatibility of low voltage connectors with lubricants and their performance additives is often overlooked when it comes to EV efficiency
Low voltage connectors create a pathway through which EV sensors, control modules, and process controls communicate to achieve e ective operation. Afton’s testing shows lubricant compatibility is essential for maintaining connector seals and preventing conductive deposit build-up on connector pins, which can break the crucial chain of communication resulting in shorting, underperformance, and failure.
With the widespread adoption of direct oil-cooled eMotors to promote EV e iciency, it is increasingly likely that electrified transmissions and eAxles share the same lubricant/ coolant as the eMotor. This fluid and its additives must therefore be compatible throughout the lifetime of the hardware with any materials encountered in the eMotor, transmission, control modules and peripheral equipment.
Low voltage connectors are easy to overlook when it comes to compatibility. A key function of a connector is to facilitate signalling between eMotor sensors, the electric drive unit (EDU) subsystems, and the EDU control module. Completely sealing connectors against the lubricant is possible, but expensive, leaving most connectors exposed to the lubricant as a liquid, vapor, or both. Vapor phase corrosion is a key risk that is less likely to be considered by engineers in the initial design where lubricant is not intended to interact with a connector. But the e ects, if uncontrolled, can be profound. Connectors come in di erent shapes and sizes but typically share common elements; a housing using material like nylon, with an elastomer seal to ensure a quality
connection. Connector pins typically contain copper, tin, silver, or related alloys; these must be protected from corrosion to avoid conductive deposit formation. Fluid and additive compatibility with the connector pins, seals, and housing must be optimized to withstand high operating temperatures and be maintained as the fluid ages. The implications of incompatibility also need to be understood clearly.
Afton Chemical has developed a bespoke rig for in-house connector compatibility testing, enabling connectors of di ering sensitivities to be paired with fluid chemistries that range from benign to more aggressive. Di erences between liquid and vapor phase are also seen, with vapor sometimes being the more aggressive medium when it comes to conductive deposit
build-up. To address this, connectors are half-submerged in test lubricant to assess both liquid and vapor phase compatibility. Test outcomes are determined by measuring electrical conductivity between connector pins, rating visual appearance, and x-ray examination for any conductive layer formation.
Results highlight several possible failure modes through incompatibility, including destruction of elastomers and coatings, as well as the build-up of conductive deposits on pins which can lead to shorting.
Success hinges on using the right additive technology for connector compatibility. Active sulphur, for example, can be particularly aggressive towards connectors but that does not mean all sulphur is to be avoided. Alternative sulphur
chemistries can be utilized e ectively to support gear performance across operating temperature ranges, delivering a level of wear protection that supports gear performance and longevity without damaging connector functioning.
At the earliest stage of development, Afton works in partnership with OEMs to apply insights from testing: compatible connector and seal materials can be recommended, alongside tailored additive chemistries that support desired gear performance.
Connector compatibility screening has already been incorporated into an OEM fluid approval process; ensuring no links in the chain of e icient eMotor operation are overlooked. a onchemical.com
An example of good or new connector pins
An example of a cracked seal
Example of conductive deposits, which can lead to shorting