It not only directly affects system energy utilization, driving range, and operating costs, but is also closely related to:

• Control strategies of the Battery Management System (BMS)
• Selection of chargers, dischargers, and power supply systems
• Overall system energy efficiency evaluation and regulatory compliance
• Battery lifetime and thermal management design

Therefore, establishing an accurate, repeatable, and engineering-oriented battery efficiency testing method is an essential part of the R&D and testing phases.

Definition of Battery Efficiency and Test Object

In practical testing, the most commonly used metric is energy efficiency:

η=Edischarge/Echarge×100%

Where:

• E_charge: Total energy absorbed by the battery during the charging process
• E_discharge: Total energy released by the battery during the discharging process

Key Point:
Battery efficiency is not an instantaneous value, but rather the integrated energy result over a complete charge–discharge cycle.

Limitations of Traditional Testing Methods

Traditional battery efficiency testing typically uses the following setup:

• A DC power supply for charging
• An electronic load for discharging
• Data collected separately and then calculated afterward

However, in practical applications, this approach presents several notable challenges:

• Charging and discharging use different instruments, leading to inconsistent measurement references
• Switching between devices introduces timing and sampling errors
• Discharged energy is converted directly into heat, resulting in high energy consumption
• High-precision power integration is difficult to achieve

For these reasons, an increasing number of testing systems are adopting a bidirectional DC power supply combined with an energy-regenerative architecture.

Battery Efficiency Testing System Architecture Based on ITECH Bidirectional DC Power Supplies

1. System Configuration (Conceptual Description)

A typical testing system architecture is as follows:

AC Grid
↑↓ (Energy Regeneration)
ITECH Bidirectional DC Power Supply (Source / Sink)
↑↓ (DC)
Battery / Battery Module / Battery Pack

Within this architecture:

• A single device performs both charging and discharging
• Voltage, current, and power measurements share the same measurement path
• Discharge energy can be fed back to the AC grid

2. Example ITECH Product Models

Depending on the power level, the following options are available:

• IT6000B / IT6000C Series
• High-precision bidirectional DC power supplies
• Suitable for cell and module efficiency testing
• Supports CC / CV / CP mode switching
• IT8000 Series High-Power Bidirectional DC Power Supplies
• Designed for pack-level and energy storage applications
• Supports parallel expansion, with power up to the MW level
• Suitable for system-level efficiency evaluation

Battery Efficiency Testing Procedure and Curve Analysis

1. Charging Phase Test Curve Explanation

Test Method: CC-CV Charging

Typical Charging Curve Description:

• The initial stage is constant current (CC) charging
• Current remains constant
• Voltage gradually rises
• Upon reaching the cutoff voltage, it enters the constant voltage (CV) stage
• Voltage remains constant
• Current gradually decreases

 Power Curve Characteristics:

• During the CC stage, power increases as voltage rises
• During the CV stage, power gradually decreases as current drops

During this phase, the ITECH bidirectional DC power supply performs in real time:

• Synchronous voltage and current sampling
• Power integration to calculate Echarge

2. Discharging Phase Test Curve Explanation

Test Method: Constant Current (CC) or Constant Power (CP) Discharge

Typical Discharge Curve Description:

• Current flows in the opposite direction
• Battery voltage gradually decreases as SOC drops
• Discharge power varies with voltage

 Discharge Energy Curve:

• Power is negative (indicating energy is fed back)
• Integration givesEdischarge

During the discharge process:

• Energy is fed back to the AC grid via IT6000 / IT8000
• The testing system itself consumes almost no additional energy

3. Energy Efficiency Calculation Example

• Charging Energy: 1000 Wh
• Discharging Energy: 940 Wh
• Battery Efficiency: 94%

This efficiency value can be compared and analyzed under:

• Different C-rates
• Different temperatures
• Different aging stages

Key Technologies for Improving Testing Accuracy (ITECH Advantages)

1. Single-Device Bidirectional Measurement to Avoid System Errors

• Charging and discharging are performed by the same device
• No device switching required
• High consistency in voltage and current measurements

2. High-Precision Power and Energy Integration

• High-resolution voltage and current sampling
• Supports long-term stable operation
• Ideal for comparative tests with small efficiency differences

3. Automated Testing and Data Output

• Supports SCPI / host software control
• Automatically performs multi-cycle efficiency tests
• Can output efficiency values, curves, and statistical data

Typical Application Scenarios

• Cell efficiency comparison testing
• Module / Pack energy efficiency evaluation
• Energy storage system circuit efficiency analysis
• Battery aging and efficiency degradation studies
• BMS algorithm verification and parameter calibration

Conclusion

The essence of battery efficiency testing is the precise quantification of the entire energy flow process.

Compared with traditional methods, a regenerative testing system based on ITECH bidirectional DC power supplies offers clear advantages in accuracy, energy consumption, and engineering consistency.

For those aiming to build a battery testing platform that is:

• High-precision
• Highly automated
• Scalable
• Low in operational cost

the bidirectional DC power supply has become the industry’s mainstream choice.