Beyond the Basics: Exploring Advanced EV Terminology with Legacy EV Education Team


As we continue the transition from measuring our vehicles power output in horsepower to kilowatts, a comprehensive understanding of EV jargon will become essential as EV and Tesla owners, builders, and tuners. To this end we’ve gathered a fresh selection of EV acronyms and terms that you should be familiar with.

Back EMF

A counter electromotive force that increases in an electric motor the faster it rotates. This reduces the working voltage of the vehicle, which reduces the amount of power reaching the wheels. Working voltage is typically the result of the supply voltage minus back electromotive force.

Bidirectional Charging

A type of EV charging that can convert DC power stored in a HV battery pack back into AC power to power AC devices, homes, and in some cases, supply AC power to the power grid.

Cycle Life

How many times a battery cell can be charged and discharged before losing performance. This can be impacted by many different

Solid State Battery 

A battery technology that uses a solid electrolyte as opposed to the flammable liquid electrolyte solution found in lithium-ion batteries. Solid state batteries are still largely in development, but once commercially available, promise to offer significant improvements in both battery energy density and safety.

Torque Vectoring

Torque vectoring is an advanced control strategy found in multi-motor EV’s wherein the system has the ability to dynamically adjust torque to each of the half-shafts. Torque vectoring improves traction, cornering capabilities, and overall stability.

HV Interlock

An EV safety feature that protects people during assembly, repair, maintenance, and operation. It uses a low voltage loop to monitor integrity of the HV circuit. If the LV signal is interrupted due to a loose or bad HV connection, a fault code is created to alter the operator.

Loss of Isolation

Galvanic Isolation is the electrical separation between two circuits which occurs when the insulation resistance that separates them is infinite or very high, i.e. There is no electrical connection between the circuits. When the grounds of two distinct circuits are at different electrical potentials, galvanic isolation is necessary to prevent the triggering of dangerous ground loops, which can generate noise that could compromise the safety of the vehicle. When two distinct circuits with different voltages connect, this is called a loss of isolation.


Manual service disconnect- Protects technicians and emergency response teams working with EVs. Connected directly to the HV battery pack, this fused, tool-free disconnect isolates the pack from the rest of the EV and protects HV cables from short circuiting when disconnected.

DC-DC Converter

This electronic device takes the high voltage DC energy available in the high voltage traction battery pack, and steps it down to approximately 12 volts to charge the 12 volt battery in an EV. In the case of a conversion, it is this device that takes the job of an alternator. EVs still retain the 12 volt battery for accessory systems such as lights, infotainment systems, door locks, power seats, and more.


A contactor is a high-voltage and high-current relay used in an EV for connecting the inverter to the traction battery back, once certain system conditions have been met.

Smart Charging

A system in which electric vehicles, charging stations (or points), and charging station owners share data connections. Smart charging allows the charging station owner to manage, restrict, and monitor the use of power to optimize energy consumption via load balancing, energy monitoring and managed charging.

That’s it for now, but stay tuned for more helpful EV terms from the talented education team at Legacy EV!

Words and photos by the Legacy EV Education Team

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