24 Battery Charge-Discharge Test Steps: Complete Parameter Reference Guide

The typical CC-CV charging cutoff current for lithium-ion batteries is 0.05C, meaning the constant-voltage phase ends once charge current decays to 5% of the cell’s rated capacity (in amp-hours). For example, a 2,000 mAh cell would use a cutoff of approximately 100 mA. Some manufacturers specify a tighter cutoff (0.02C–0.03C) for higher-precision capacity calibration, or a looser cutoff (0.1C) for faster production-line formation where slightly reduced full-charge capacity is an acceptable trade-off for throughput. The CC-CV charge step (Section 2.6) is the standard protocol implementing this behavior: a constant-current phase charges the cell to a target voltage (commonly 4.2 V for standard Li-ion chemistries), then the constant-voltage phase holds that voltage while current decays naturally to the specified cutoff.

Standard CC-CV charging has two stages: a constant-current (CC) stage followed by a constant-voltage (CV) stage. In the CC stage, the charger delivers a fixed current (e.g., 1C) until the cell reaches its target charge voltage. The protocol then automatically transitions to the CV stage, holding that voltage constant while current naturally decays as the cell approaches full charge, until reaching a cutoff current (commonly 0.05C). Some fast-charging protocols use a multi-stage CC-CC-CV approach (multiple step-down constant-current stages before the final CV hold) to balance charge speed against heat generation and lithium-plating risk, but the fundamental two-stage CC-CV structure remains the basis for standard lithium-ion charging.

Galvanostatic (constant-current) charge-discharge testing for capacity, efficiency, and cycle life evaluation typically combines three core steps from this 24-step catalog: a CC (or CC-CV) charge step, a rest step for polarization recovery, and a CC discharge step, wrapped inside a Cycle step that repeats this sequence for a defined number of cycles (e.g., 100–1,000+). Coulombic efficiency is calculated each cycle as discharge capacity divided by charge capacity. Cycle life testing typically sets the Cycle step’s transition condition to a capacity-fade threshold (e.g., terminate when discharge capacity falls below 80% of the initial value), which directly defines the cell’s measured cycle life under the tested conditions.

EIS, GITT, and PITT are three distinct electrochemical characterization steps that probe different aspects of battery behavior. EIS (electrochemical impedance spectroscopy) applies a small AC perturbation across a frequency range (typically 0.01 Hz–100 kHz) to separate impedance contributions—such as ohmic resistance, charge-transfer resistance, and diffusion impedance—based on their characteristic frequency response, producing Nyquist and Bode plots. GITT (galvanostatic intermittent titration technique) applies short DC current pulses followed by relaxation periods to calculate the lithium-ion diffusion coefficient at each state of charge. PITT (potentiostatic intermittent titration technique) instead applies small voltage steps followed by relaxation, used primarily to study phase-transition thermodynamics and solid-electrolyte-interface behavior. EIS is generally faster and used for interfacial/SEI analysis, while GITT and PITT provide more detailed state-of-charge-resolved transport and thermodynamic data at the cost of longer test time.

A pulse step applies short, intermittent current pulses (charge and/or discharge) to a cell to measure its dynamic resistance and voltage response— most commonly implemented as a Hybrid Pulse Power Characterization (HPPC) test. By applying defined-amplitude current pulses at various states of charge and measuring the instantaneous voltage drop, HPPC testing extracts internal resistance (DC-IR) as a function of state of charge, which is essential data for battery management system (BMS) power-limit calculations in electric vehicles. Pulse testing also validates a cell’s response to real-world dynamic loads—such as acceleration events in EVs or burst current draws in power tools and wearables—making it a critical step for application-realistic battery qualification beyond standard constant-current cycling.