Glossary
Every EV conversion tells a story — a story of passion, innovation, and rebirth. At Fuel2Electric, we believe understanding each component brings you closer to the art of electrifying a classic. From motors to modules, this glossary breaks down the essential parts that make your EV project possible. Whether you’re a builder, enthusiast, or simply curious, here’s what makes electric motion truly come alive.
AC Compressor / Vacuum PumpElectric AC compressors and vacuum pumps replace the belt-driven accessories removed with the ICE. They power climate control, brake boosters and HVAC systems so you retain comfort and safety after conversion — a neat bit of engineering that keeps cabin comfort and braking feel modern without sacrificing packaging. | Auxiliary 12V BatteryThe 12V battery remains essential in an EV: it powers lights, infotainment, and control electronics when the main pack is asleep. The DC/DC converter keeps it charged while driving. In conversions, choosing the right 12V capacity and mounting location prevents nuisance faults and ensures seamless accessory operation. | Battery Capacity (kWh)Measured in kilowatt-hours, battery capacity is the total energy the pack can store — the EV equivalent of tank size. More kWh gives more range but increases weight and cost. In conversions we balance capacity against vehicle mass and intended use to hit real-world range targets without compromising handling. |
Battery Management System (BMS)The BMS monitors cell voltages, temperatures and currents, balances cells, and enforces safe charge/discharge limits. It’s the pack’s nervous system — preventing overcharge, deep discharge and thermal events. A robust BMS is central to safety and longevity in any conversion. | Battery Manual Service Disconnect (MSD) / Kill SwitchA positive mechanical disconnect that allows technicians or owners to isolate the high-voltage pack for safe service or transport. Simple, obvious, and indispensable — the MSD is the physical assurance that no high-voltage energy is live during maintenance. | Battery Modules Configuration (e.g., 3S4P)Module configuration defines voltage and capacity: for example, 3S4P means three cells in series (voltage) and four in parallel (capacity). Series increases pack voltage (helpful for power), parallel increases energy and current capacity — understanding this lets builders match pack specs to motor and inverter requirements. |
Battery PackThe battery pack is the energy reservoir assembled from modules and cells to meet voltage and capacity goals. Placement, structure and cooling access shape range, balance, and safety. A well-designed pack is the backbone of a professional conversion — it dictates packaging, thermal strategy and serviceability. | Charging Capacity (kW)Charging capacity (measured in kW) indicates how fast a vehicle can accept energy. It depends on the onboard charger, inlet and battery thermal limits. Higher kW equals faster recharges — but only when the pack and cooling systems are designed to handle that power safely. | Charging Port / InletThe inlet is where your vehicle connects to the grid — choices include Type 1/Type 2 for AC and CCS/CHAdeMO for DC fast charging. Picking the right inlet determines infrastructure compatibility and real-world charging convenience for owners. |
Charger Controller / Charge Management UnitThis module negotiates charging current, communicates with the BMS, and enforces safety during AC or DC charging. It’s the intelligence that ensures the pack receives the right amount of energy under the right conditions — crucial for safe, fast and battery-friendly charging profiles. | Contactors (High-Voltage Relays)Contactors are heavy-duty relays used to connect and disconnect high-voltage circuits on command from the VCU or BMS. They control inrush, isolation and emergency shutdowns — pick them to match current and thermal loads for safety and longevity. | Cooling PlatesCooling plates are thermally conductive plates that contact battery modules to pull heat into the coolant loop. They help maintain cell temperature uniformity — a small addition that significantly improves pack performance and life in high-density or performance-oriented conversions. |
Cooling Pump / Radiator / Heat ExchangerElectric pumps circulate coolant through batteries and power electronics, while radiators and heat exchangers dump that heat to the air. Packaging for airflow and serviceability is a conversion challenge with big returns in reliability and sustained performance. | DC/DC ConverterThis device steps high-voltage pack energy down to 12V for lights, infotainment, and safety systems — replacing the alternator. Efficient DC/DC design minimizes parasitic loss and keeps the 12V network healthy even when the main pack cycles. | Diagnostic Port / Data LoggerDiagnostic ports and loggers allow access to fault codes, telematics and performance data. For builders and fleet managers, logged metrics and error histories are invaluable for tuning, preventative maintenance and reliability improvements. |
Emergency Power Safety CutoffAn emergency cutoff (manual or automatic) isolates the high-voltage system instantly in crash or fire scenarios. It’s a required safety measure in professional builds and provides first responders with a clear isolation point. | Energy Management & Recovery StrategyThis software-level strategy balances regen, thermal limits and SOC to maximize usable range while protecting components. Smart energy strategies make everyday driving simpler and keep operating costs low — a big differentiator for fleets and enthusiasts alike. | Fuses and Protective DevicesFuses, fusible links and breakers stop overcurrent events and protect wiring and components. Proper coordination of protective devices with contactor ratings and cable sizing is fundamental to preventing damage and fire in any conversion. |
High-Voltage Cables and ConnectorsHigh-voltage cables (orange, shielded) carry battery energy between pack, PDU, inverter and charger. Cable sizing, routing and connector choice affect voltage drop, heat and serviceability — and must meet safety standards in professional conversions. | High-Voltage Interlock Loop (HVIL) Monitoring & Service InterlocksHVIL is a safety circuit that disables high-voltage systems if an enclosure or connector is opened. Coupled with software interlocks, it ensures the system won’t energize during service — a simple but powerful layer of protection. | Inertia SwitchAn inertia switch trips during an impact to cut power to high-voltage circuits, acting as an automatic safety disconnect in crash scenarios. It protects occupants and emergency responders by quickly isolating stored energy after a collision. |
Instrument Cluster / Display InterfaceThe cluster displays SOC, range, power flow and system warnings. Converting dashboards from fuel gauges to EV-centric displays helps drivers understand energy dynamics and makes the electrified car feel modern and intuitive. | Inverter (Motor Controller)The inverter converts DC from the battery into variable-frequency AC for the motor, controlling torque, speed and regen through pulse-width modulation and power electronics. Matching inverter voltage and thermal capacity to your motor is crucial for reliable performance. | Pre-Charge Resistor CircuitPre-charge limits inrush current at power-up by charging inverter and PDU capacitors gradually. Without it, huge surges can damage components — this small circuit is essential for safe, repeatable power sequencing in conversions. |
Power Distribution Unit (PDU)The PDU is the high-voltage junction box that routes power to inverter, OBC, DC/DC and other loads. With contactors and fuses inside, it simplifies wiring and improves safety and serviceability compared with ad-hoc wiring harnesses. | Power Steering / Brake Assist IntegrationElectric pumps and actuators replace hydraulic assists or integrate with existing systems to preserve steering and braking feel. Thoughtful integration keeps the vehicle’s personality intact while meeting modern safety expectations. | Regenerative Braking SystemRegenerative braking converts kinetic energy into electrical energy during deceleration, feeding it back to the battery. Properly tuned regen improves efficiency and can provide a satisfying one-pedal driving experience when blended correctly with friction brakes. |
State of Charge (SOC)SOC is the real-time estimate of usable energy remaining in the battery, calculated from models using voltage, current integration and temperature compensation. Accurate SOC builds driver confidence and underpins reliable range predictions. | Thermal Fuse / Battery Sensor SystemTemperature sensors and thermal fuses detect hotspots or abnormal conditions in cells and modules; when thresholds are exceeded they trigger protective actions. Early detection prevents small issues from cascading into serious thermal events. | Thermal Management SystemThe thermal system uses pumps, coolant loops and heat exchangers to keep batteries, motor and inverter in optimal temperature windows. Good thermal design preserves performance and extends component life across climates and driving styles. |
Throttle (Accelerator) Pedal SensorThe pedal sensor converts driver input into electrical signals (Hall-effect or potentiometer) that the VCU or inverter uses to request torque. Redundant sensing and careful mapping create a predictable, safe throttle response in conversions. | Vehicle Control Unit (VCU)The VCU coordinates motor commands, regen, thermal limits, and safety interactions between inverter, BMS and PDU. For conversions, a flexible VCU shortens integration time and lets builders tune drive feel while enforcing system-level safety. | Inverter (Motor Controller)(See earlier entry) The inverter shapes battery DC into controlled motor power, handles regen and manages torque and speed. Choosing the right inverter for voltage, current and thermal envelope is vital for performance and reliability. |
