ASE XEV2 key terms

Any vehicle circuit that operates above 60 volts DC or 30 volts AC RMS under common industry thresholds; such circuits demand insulated tools, rated test equipment, and a documented disablement procedure before any service work begins.

Rubber gloves rated for roughly 1,000 volts AC and 1,500 volts DC, worn with leather protectors whenever hands enter an energized HV zone; they must be air-tested before each use and electrically retested on schedule.

The arc-rated clothing, face shield, safety glasses, and insulated gloves a technician wears to reduce injury from electric shock, arc flash, and battery electrolyte splash while servicing high-voltage vehicles.

A rapid energy release caused by current arcing through air at a fault, producing intense heat, light, and pressure; it can ignite clothing and cause severe burns without any direct contact with conductors.

Working with one hand while the other stays clear of the vehicle, so an accidental current path runs through an arm and hand rather than across the chest and heart; a core habit when probing live circuits.

A safety classification for test instruments built to survive transient overvoltages on distribution-level circuits; HV vehicle diagnosis requires meters, leads, and probes rated CAT III at or above the working voltage.

The controller that tracks cell voltages, pack current, and temperatures, estimates state of charge, commands contactors and balancing, and reports safe operating limits to the vehicle controllers to protect the pack.

The percentage of usable energy presently stored in the pack compared with its full capacity; it is estimated from current integration, open-circuit voltage, and cell models rather than measured directly.

A measure of how much capacity and power capability the pack retains compared with when it was new, shaped by age, cycling, and heat; used for range estimates, warranty decisions, and resale evaluation.

Equalizing charge among series-connected cells so none is pushed above or below its safe window; passive balancing drains energy through resistors, while active balancing transfers charge from stronger to weaker cells.

A self-accelerating overheating condition inside a cell where heat generation outpaces heat removal, raising temperature and internal pressure until venting, smoke, or fire occurs and may spread to neighboring cells.

A heavy-duty, normally open relay inside the pack that links the cells to the vehicle's high-voltage bus only after the BMS confirms insulation, interlock, and crash-signal checks have passed.

A measurement of how completely HV conductors are isolated from the chassis; a low reading reveals a leakage path from moisture, damage, or contamination and usually sets an isolation fault code.

A sealed assembly of individual cells wired in series and parallel that forms a serviceable building block inside the pack; module count, shape, and voltage vary widely by manufacturer and platform.

The electric machine that turns electrical energy into wheel torque and, during deceleration, turns wheel motion back into electricity; its speed and torque are governed by the inverter.

A motor whose rotor carries permanent magnets and locks to the inverter's rotating field; it delivers high efficiency and power density, but spinning the shaft with power removed can create hazardous voltage.

Recovering kinetic energy by driving the traction motor as a generator during deceleration, pushing current back through the inverter to the pack; software blends this braking with the friction brakes.

A rotor position sensor that reports motor shaft angle to the inverter so current pulses are timed to the magnetic field; a lost or noisy signal normally blocks propulsion and sets a fault.

A hybrid layout that uses a planetary gearset and two motor-generators to blend engine and electric power continuously, varying the ratio electronically instead of shifting fixed gear steps.

A fixed-ratio gear set that multiplies motor torque and lowers shaft speed to the wheels, because most traction motors spin far faster than the axle turns at road speed.

A power electronics assembly that switches battery DC into three-phase AC for the traction motor and converts generated AC back to DC during regeneration; it also houses gate drivers, sensing, and the DC bus.

An insulated-gate bipolar transistor, a fast semiconductor switch used in inverter and converter power stages that combines high input impedance with low conduction loss at high current and voltage.

A device that steps the high-voltage pack down to charge the 12-volt battery and run accessories; when it fails, the auxiliary battery drains and vehicle electronics begin shutting down.

A resistor path that fills the inverter's bus capacitors gradually before the main contactor closes, limiting inrush current that could weld contactor tips or stress power semiconductors.

A switching method that rapidly turns a semiconductor on and off, varying duty cycle to control average voltage and current; the inverter uses it to shape a smooth three-phase AC waveform.

A large capacitor across the inverter's DC input that smooths ripple and feeds the fast current pulses the switches demand; it holds a dangerous charge after shutdown until discharged or verified.

The off-board charging hardware that delivers AC or DC power to the vehicle and signals available current and safety status through the charge connector and cable assembly.

The signaling circuit in the charge connector that lets the station and vehicle negotiate available current, confirm the plug is latched, and cut power before separation under load.

The vehicle-mounted converter that rectifies AC from a wall outlet or public station into high-voltage DC for charging the pack; DC fast charging bypasses it and feeds the battery directly.

High-power charging in which an off-board charger delivers regulated DC straight to the pack, skipping the on-board charger; session limits and safety are coordinated by charging-controller communication.

The pumps, coolant loops, chillers, and heaters that hold cells within a safe temperature window during driving and fast charging, protecting power output and slowing long-term degradation.

A removable plug or lever that opens the high-voltage circuit at the battery for service; removing it stops pack output, though capacitors and other energized sections still require verification.

The practice of isolating an energy source, attaching a personal lock and tag, and confirming zero stored energy so the circuit cannot be re-energized while a technician is working on it.

Proving with a correctly rated meter, checked on a known live source before and after the test, that no hazardous voltage remains on the conductors or terminals about to be touched.

A low-current monitoring circuit routed through every HV connector and service cover; an open loop tells the controller a connection is broken, so contactors open and propulsion is disabled.

An instrument that applies an elevated test voltage to measure resistance in the megohm range between HV conductors and chassis, confirming isolation quality after a repair or when a leak is suspected.

Joining conductive enclosures and chassis points so they rest at the same electrical potential, removing any voltage difference that could drive current through a person touching two surfaces.