Battery Charge–Discharge Test System — Operating Principle
- Product Description
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A battery charge‑discharge testing system—also commonly referred to as battery test equipment, a battery test cabinet, or BTS—is an automated device that simulates real‑world battery operating conditions, precisely controls current and voltage, collects data, and evaluates the battery’s performance and safety status.
I. Overall Work Logic
The system, comprising a hardware power loop, a control circuit, and software algorithms, performs the following sequence on the battery: constant‑current charging → constant‑voltage charging → constant‑current discharging → rest → cycling. Simultaneously, it acquires real-time data on voltage, current, temperature, capacity, internal resistance, and other parameters, ultimately generating performance curves and reports.
It can be understood as a high-precision three-in-one system comprising an electronic load, a programmable power supply, and a data logger.
II. Principle of Charging Operation
Constant Current Charging (CC)
Internal to the system
Programmable Constant Current Source
Output a stable current to the battery.
The voltage gradually increases as the state of charge rises, until it reaches the set cutoff voltage (e.g., 4.2 V for lithium batteries).
Constant Voltage Charging (CV)
The voltage remains constant, while the current gradually decreases as the battery becomes fully charged.
When the current drops to the set threshold (e.g., 0.02C), the battery is considered fully charged, and charging is stopped.
Protection mechanism
Overvoltage, overcurrent, overheating, and reverse polarity protection
Automatically shuts off when the set conditions are met, preventing bulging and ignition.
III. Discharge Operating Principle
Discharge is achieved using an electronic load, which can be implemented in two main ways:
Energy-consuming discharge (resistive/thermal)
The electric current passes through a high-power resistor, converting electrical energy into heat and dissipating it.
Low cost, suitable for low-power and laboratory equipment.
Energy-Regenerative Discharge (Grid-Connected / Grid-Return)
Convert the direct current discharged from the battery into alternating current,
Return to the power grid
Energy-efficient and low-heat generation, suitable for power batteries and large-scale production-line testing.
The discharge process typically proceeds as follows: constant-current discharge (CC) → voltage drops to the cut-off voltage (e.g., 2.8 V or 3.0 V for lithium batteries) → discharge is terminated, and the actual capacity is calculated by multiplying the discharge time by the current.
IV. Data Acquisition and Control Principles
High-precision sampling
Voltage sampling: millivolt-level accuracy
Current sampling: at the milliampere level or even the microampere level
Temperature Sampling: Real-time Monitoring via NTC Thermistor/Temperature Sensor
Closed-loop control (PID)
The system continuously compares.
Setpoint vs. Actual Value
Real-time adjustment of output power ensures highly stable current and voltage.
Sequence control is automatically executed according to the preset work steps:
Charging
Let stand
Discharge
Cycle
DCR DC Internal Resistance Test
Pulse testing
HPPC Hybrid Power Pulse Characteristic Testing
V. Typical Testing Procedure (Most Common Principle Demonstration)
Take lithium battery capacity testing as an example:
Constant-current charging
To the upper voltage limit
Constant-voltage charging
Cut-off at very low current
Let stand
Stabilized voltage
Constant-current discharge
To the lower limit voltage
Calculation:
Discharge capacity = Discharge current × Discharge time
Repeated iterations yield
Cycle life, capacity fade rate
VI. Summary of Core Functions
Precise measurement of: capacity, internal resistance, voltage platform, and charge–discharge efficiency.
Verification: Rate capability, high- and low-temperature performance, cycle life
Safety Assurance: Safety boundary testing for overcharge, overdischarge, short circuit, overheating, and other conditions.
In a nutshell: it delivers and withdraws precisely controlled electrical energy, continuously monitoring the battery’s response to determine its performance, lifespan, and safety.
If you’d like, I can draw another simplified block diagram for you, or explain the differences in separate versions for small cells, power batteries, and energy‑storage batteries.
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Huizhou Jinghui Instrument and Equipment Co., Ltd.
Service Hotline:400-1331-882
No. 13, Jinda Road, Huinan Science and Technology Park, Huizhou City, Guangdong Province
E-mail:jh@jhyq.com
