A CC-CV charging profile (Constant Current–Constant Voltage) is a standard battery charging method where charging starts with a fixed constant current (CC) phase and then transitions to a constant voltage (CV) phase as the battery approaches its target voltage. During the CV phase, the charger holds voltage steady while current gradually tapers down, helping protect the battery and maximize usable capacity.
What Is a CC-CV Charging Profile?
CC-CV is a two-stage charging behavior used for most modern lithium-ion batteries, including EV battery packs.
– CC phase: current is held constant (or near constant), and battery voltage rises
– CV phase: voltage is held constant, and current decreases (“tapering”) as the battery fills
This profile explains why fast charging is rapid at lower state of charge (SoC) and slows down near high SoC.
Why CC-CV Charging Matters in EV Charging
CC-CV directly shapes charging time, battery stress, and the user experience.
– Defines the real-world charging curve seen on DC fast chargers and many AC charging scenarios
– Helps protect battery health by limiting high-voltage stress near full charge
– Explains tapering behavior that reduces power at high SoC, impacting bay turnover and session duration
– Supports smarter site planning and messaging for fleets, public hubs, and workplace charging
For operators, understanding CC-CV helps set realistic expectations for charging speed and throughput.
How CC-CV Charging Works
A typical CC-CV sequence looks like this:
– The charger and vehicle agree a target current and voltage limit through communication
– CC phase delivers high current until the battery voltage reaches a set threshold
– The system transitions into CV phase when the battery approaches its voltage limit
– Current tapers down to keep voltage constant and stay within battery safety limits
– Charging ends when current falls below a cutoff threshold, or when the target SoC is reached
In EVs, the Battery Management System (BMS) continuously controls allowable current based on voltage, temperature, and battery condition.
CC-CV in AC vs DC Charging
CC-CV is a battery charging principle, but where it is controlled depends on charging type:
– AC charging
– The vehicle’s onboard charger converts AC to DC and applies a CC-CV-like profile internally
– The EVSE mainly provides available AC power; the vehicle controls the battery charge profile
– DC fast charging
– The charger provides DC directly to the battery system under BMS control
– The charger output follows BMS requests, which typically result in CC then CV tapering
Typical CC-CV Behavior Across State of Charge
CC-CV helps explain common patterns during a session:
– High power early in the session (low-to-mid SoC) during CC phase
– A visible power drop as the vehicle transitions toward CV
– Increasing taper near high SoC (e.g., above ~70–80% in many EVs, vehicle-dependent)
– Longer “top-up” time from high SoC to full, even if only a small kWh amount is added
Exact transition points vary by EV model, battery chemistry, temperature, and battery aging.
Key Benefits of CC-CV Charging Profiles
– Fast energy delivery during the early phase of charging
– Better battery protection and safety near high SoC
– Predictable charging behavior for control systems and planning
– Compatible with most lithium-ion battery technologies used in EVs
Limitations to Consider
– Charging speed is not constant for the full session due to CV tapering
– High SoC charging can be time-inefficient for public fast charging turnover
– Battery temperature and BMS limits can reduce current even during the CC phase
– Degraded or cold batteries often enter taper earlier and charge more slowly
– Site power availability and active power throttling can further shape the observed curve
Related Glossary Terms
Charging Curve
State of Charge (SoC)
Battery Management System (BMS)
DC Fast Charging
Battery Thermal Limits
Battery Aging
Active Power Throttling
Power Derating
C-rate
ISO 15118