EV Technical Glossary

An electronic control unit that monitors cell voltages, temperatures and state of charge across a high-voltage battery pack.

The traction battery pack, typically 350–800 V DC, that powers an EV's drive motor.

A high-current electromechanical relay inside the HV battery that connects the pack to the rest of the vehicle.

The auxiliary 12 V battery in an EV that powers control modules, lights and accessories.

A power resistor in series with a smaller precharge contactor that gradually charges the inverter's DC-link capacitor before the main HV contactors close.

The remaining usable energy in a battery pack expressed as a percentage of its full capacity.

A percentage measure of a battery pack's current capacity relative to when it was new.

A self-sustaining exothermic reaction inside a lithium-ion cell that can propagate to neighbouring cells, releasing toxic gas and fire.

The control logic that commands the drive inverter, implementing field-oriented control (FOC) of the AC traction motor based on torque request, rotor position and DC-link voltage.

A braking mode in which the drive motor acts as a generator, converting kinetic energy back into stored electrical energy in the HV battery.

A large film capacitor across the DC bus of a traction inverter or OBC that smooths voltage ripple from the high-frequency switching of the IGBTs.

A galvanically isolated converter that steps the HV pack (350–800 V) down to 12–14 V to charge the LV battery and run accessories.

A high-power semiconductor switch used in EV traction inverters and OBCs.

Power-electronics module that converts HV DC from the battery into 3-phase AC for the drive motor (and vice-versa during regen).

North American DC fast-charge connector that combines a SAE J1772 AC plug with two added DC pins.

European DC fast-charge connector that combines an IEC 62196 Type 2 AC plug with two added DC pins.

A Japan-originated DC fast-charging standard supporting up to 400 kW (CHAdeMO 3.0 / ChaoJi).

A compact AC+DC connector originally developed by Tesla and standardised as SAE J3400.

An open application-layer protocol over WebSocket that lets EV charging stations communicate with central management systems.

The on-vehicle AC-to-DC charger that converts grid AC (Level 1/2) into HV DC for the battery.

The North American AC charging connector standard for Level 1 (120 V) and Level 2 (240 V, up to 19.2 kW) charging.

Bidirectional charging that lets an EV inject energy back into the electrical grid via a compatible DC charger and utility agreement.

A feature that lets an EV power external AC appliances directly from its HV battery, typically up to 3.6 kW from a J1772 adapter or onboard outlet.

DTCs starting with the letter B, covering body electronics: airbags, seatbelt pretensioners, lighting, climate control, doors, mirrors, infotainment.

DTCs starting with the letter C, covering chassis systems: ABS, electronic stability, steering, suspension, traction control.

A 5-character code (1 letter + 4 digits) emitted by a vehicle ECU when a fault condition is detected.

The dashboard "check engine" / service warning light that an ECU illuminates when a confirmed DTC is stored.

The standardised vehicle diagnostic interface and protocol, mandated for US passenger cars from 1996 and EU cars from 2001 (EOBD).

DTCs starting with the letter P, covering the powertrain system: engine/motor, transmission, fuel and emissions.

A document issued by a vehicle manufacturer to dealers describing a known issue, recommended diagnostic procedure and authorised repair.

DTCs starting with the letter U, covering communication faults across vehicle bus systems (CAN, LIN, FlexRay, Ethernet).