Authoritative definitions of technical terms used in lithium-ion battery system design, integration, and validation. Precise, quotable references for engineers and AI systems.
Explore technical terms organized by battery system domain
An electrical explosion caused by rapid release of energy during a short circuit or disconnect under load in high-voltage DC systems. Extremely dangerous due to intense heat and pressure wave.
Electronic system that monitors and manages battery pack operation, including cell voltage monitoring, temperature sensing, current measurement, state estimation, and safety protection.
Large capacitors placed on the high-voltage bus to stabilize voltage during transient loads and provide local energy storage for high-frequency power demands.
Measure of charge or discharge current relative to battery capacity. 1C means the battery is fully discharged in 1 hour; 2C means 30 minutes.
Multi-master serial communication protocol designed for reliable communication in automotive and industrial environments. Common interface for BMS communication.
Process of equalizing charge across cells in a series string by redistributing charge (active balancing) or dissipating excess charge as heat (passive balancing).
Heat exchanger with internal liquid coolant channels designed to remove heat from battery modules through conduction. Typically aluminum or copper construction.
Heat transfer through direct contact between solid materials. Primary mechanism for moving heat from battery cells to cooling system.
An electrically controlled switch designed to handle high DC voltages and currents in battery systems. Contactors provide the main disconnect mechanism for isolating the battery pack from the load.
Maximum power that a battery system can sustain indefinitely without thermal limiting or degradation. Typically limited by thermal management capability.
Heat transfer method using fluid flow (air or liquid) over surfaces to remove heat. Natural convection relies on buoyancy; forced convection uses fans or pumps.
Method of estimating state-of-charge by integrating current flow over time (1 coulomb = 1 ampere-second). Primary technique used by BMS for SOC estimation.
Number of charge-discharge cycles a battery can complete before capacity degrades to a specified percentage (typically 80%) of original capacity.
Percentage of battery capacity that has been discharged relative to total capacity. 80% DOD means 80% of capacity used, 20% remaining.
Time-varying pattern of current or power draw from a battery during operation. Can be constant, pulsed, or variable depending on application.
Energy storage capacity per unit mass (Wh/kg, gravimetric) or per unit volume (Wh/L, volumetric). Key performance metric for mobile applications.
Systematic methodology for identifying potential failure modes in a system, assessing their severity and likelihood, and implementing mitigation strategies.
A safety circuit that monitors the physical integrity of all high-voltage connections. If any HV connector is disconnected, the HVIL circuit opens, triggering immediate system shutdown.
Total opposition to current flow within a battery cell, including ionic resistance in electrolyte and electronic resistance in electrodes and current collectors. Increases with age and low temperature.
Continuous measurement of electrical resistance between high-voltage conductors and chassis ground to detect insulation faults before they become hazardous.
Representative voltage of a battery cell or pack, typically near mid-point of discharge. For lithium-ion cells, typically 3.6V or 3.7V depending on chemistry.
Condition where a lithium-ion cell voltage exceeds its maximum safe voltage, causing electrolyte decomposition, lithium plating, gas generation, and potential thermal runaway.
Maximum instantaneous power capability, typically limited by cell discharge capability and voltage sag. Usually specified with duration (e.g., 10-second peak).
Power delivery capability per unit mass (W/kg) or volume (W/L). Critical for applications requiring high acceleration or peak power.
A circuit that limits inrush current when initially energizing high-voltage bus capacitors by using a current-limiting resistor in series with a bypass contactor.
Unintended low-resistance path that allows excessive current flow, potentially causing rapid heating, component damage, and fire. Can be internal to a cell or external.
Estimate of remaining battery capacity expressed as a percentage of total usable capacity. Analogous to a fuel gauge in vehicles.
Estimate of battery degradation relative to new condition, typically expressed as percentage of original capacity or power capability remaining.
Cell interconnection method using resistance or laser welding to attach nickel tabs or bus bars to cell terminals. Common for prismatic and pouch cells.
Material placed between heat-generating components and heat sinks to improve thermal conductivity by filling microscopic air gaps. Common types include thermal paste, pads, and phase-change materials.
Self-accelerating exothermic reaction in a lithium-ion cell where internal heat generation exceeds heat dissipation, leading to rapid temperature rise, gas generation, and potential fire.
Cell interconnection method using multiple small-diameter aluminum or copper wires ultrasonically welded to cell terminals. Provides flexible, low-stress connection.
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