ASE XEV2 cheat sheet

ISO 6469 / SAE J1673 define high voltage as greater than 60 V DC or greater than 30 V AC RMS; anything at or above that is treated as hazardous.

Body current effects at 60 Hz: about 1 mA is perception, 10-16 mA is the let-go threshold, and roughly 50 mA can induce ventricular fibrillation.

Class 0 rubber insulating gloves are rated 1,000 V AC / 1,500 V DC, air-tested before each use, and electrically retested every 6 months.

IEC 60900 insulated hand tools are proof-tested at 10,000 V and rated for live work up to 1,000 V AC.

Use a CAT III minimum meter rated for the system voltage; a CAT III 1000 V meter is required for pack-level measurements.

Dry skin hand-to-hand resistance is roughly 1,000 to 100,000 ohms; wet, sweaty, or broken skin drops to a few hundred ohms and greatly raises shock current.

NFPA 70E arc-rated clothing is selected from the incident energy in cal/cm squared calculated at the working distance.

Remove jewelry, metal watches, and rings before HV work; loose conductive items are a direct short-circuit path.

Standard HV PPE set: safety glasses plus arc-rated face shield, insulating gloves with leather protectors, arc-rated outerwear, and non-conductive footwear.

Typical automotive lithium-ion cell: nominal 3.6-3.7 V, charge limit 4.1-4.2 V, discharge floor roughly 2.5-3.0 V.

Pack energy (kWh) = amp-hour capacity x nominal pack voltage / 1,000.

A resting cell-to-cell spread above roughly 50-100 mV on a lithium pack indicates a weak cell or a balancing fault.

Open-circuit voltage indicates state of charge only after the pack has rested, and resolution is poor in the flat 30-80 percent SOC region.

Isolation pass criterion per ISO 6469-1 is at least 100 ohms per volt of pack voltage, so a 400 V pack must measure 40,000 ohms or more.

Passive balancing bleeds energy from the highest cells through resistors as heat; active balancing transfers charge between cells.

Internal resistance rises with age and low temperature and is measured by a current-step test or AC impedance method.

Thermal runaway progression: self-heating near 60-80 degrees C, venting with sweet or solvent odor, then ignition; off-gas sensors give early warning.

The manual service disconnect or service plug is the physical break point in the pack circuit; remove it and keep it on your person.

Permanent-magnet motor back-EMF is proportional to speed, so spinning wheels can generate hazardous voltage at the inverter terminals even after disablement.

Mechanical power (W) = torque (N-m) x angular speed (rad/s); rad/s = rpm x 2pi / 60; 1 hp = 0.746 kW.

In field-oriented control, the d-axis current controls flux (including field weakening) and the q-axis current controls torque.

The inverter needs continuous rotor position from a resolver or encoder to commutate; loss of the signal forces a shutdown.

Regenerative torque is limited by state of charge, pack temperature, motor speed, and inverter temperature.

Series hybrid: the engine only drives a generator. Parallel hybrid: engine and motor both drive the wheels. Powersplit: a planetary gear set blends both paths.

Most EVs use a single-speed reduction gear of roughly 8:1 to 12:1; a few use two speeds to improve high-speed efficiency.

Field weakening reduces d-axis flux above base speed to extend the motor's speed range at reduced torque.

The IGBT is voltage-controlled with a fixed on-state drop; the SiC MOSFET has lower conduction and switching loss and can switch at higher frequency.

DC bus capacitors store lethal energy; never assume they are discharged just because the OEM wait time elapsed - always verify.

A boost converter stage raises pack voltage (for example 350 V to 650 V) to feed the inverter in many designs.

Dead time is a short delay between turning off one switch and turning on its complement; it prevents shoot-through current.

Typical inverter PWM switching frequency is roughly 8-20 kHz, above the audible range.

The HV-to-12 V DC-DC converter replaces the alternator, typically rated 1.5-3 kW; its failure drains the 12 V battery and causes a no-start.

Overcurrent protection uses desaturation detection or shunt/current-sensor feedback in the gate driver circuit.

Inverter and motor cooling is by liquid cold plate; low coolant flow or high coolant conductivity causes derating or shutdown.

With the pack isolated, inverter insulation checks are made phase-to-ground and phase-to-phase with an insulation tester.

SAE J1772 control pilot: maximum available current in amps = PWM duty cycle percent x 0.6.

The proximity pilot resistor value built into the plug encodes the cable's current capacity to the vehicle.

AC Level 1 is 120 V at about 1.4 kW; Level 2 is 240 V at roughly 3.3-19.2 kW; DC fast charging is 50-350 kW at 400-800 V.

CC-CV profile: constant current until the cell voltage limit, then constant voltage with tapering current; fast charge tapers above about 80 percent SOC.

The on-board charger performs rectification, power-factor correction, and isolated DC regulation; its rating caps the AC charge rate.

Connector families: J1772 for AC, CCS1 and NACS for AC and DC, CHAdeMO for DC.

DC fast charging bypasses the on-board charger and feeds the pack through dedicated contactors and a charge port controller.

The HV-to-12 V DC-DC converter maintains the 12 V system whenever the pack contactors are closed.

Cabin heat comes from a HV PTC heater or heat pump; cabin cooling uses a HV electric compressor - both load the pack.

Disablement sequence: key off, move the fob more than 5 m away, disconnect 12 V negative, wait the OEM time, remove the service disconnect, then verify and lock out.

Three-point dead check: HV positive to HV negative, HV positive to chassis, and HV negative to chassis; each must read below the OEM limit, typically 30 V or less.

Verify the voltmeter on a known live source immediately before and immediately after the dead check.

Never open a HV connector under load; the sustained arc can melt terminals and cause severe burns.

Capacitor discharge may be active (bleeder circuit) or passive; the OEM wait time is a minimum, not a guarantee of zero volts.

Reconnect in reverse order: service disconnect last, then 12 V, then clear DTCs and run an insulation resistance test before release.

Apply personal lockout/tagout and keep the service disconnect key or plug on your person for the duration of the repair.

A two-person rule with a spotter reduces the risk of an unobserved arc or shock in the service bay.

A post-repair insulation resistance test confirms no new conductive path to chassis before the vehicle is returned.