17011 Programmable Charge/Discharge Tester

The Chroma 17011 Battery Cell Charge and Discharge Test System is a high precision system designed specifically for testing lithium-ion battery (LIB) cells, electrical double layer capacitors (EDLC), and lithiumion capacitors (LIC). It is suitable for product development, quality control, and is helpful to characteristic research, cycle life testing, product screening, and quality assessment.

The Chroma 17011 has linear circuit and regenerative AC/DC bi-directional models for different applications. The linear circuit test systems feature extremely low output noise and high measurement accuracy and are applicable for testing small and medium sized energy storage components. The regenerative bi-directional test systems with high efficiency, power saving, low heating, and stable measurement capabilities suit testing medium and large size energy storage components or power type battery cells and fit green energy low carbon emission production.

In addition to the commonly used constant current (CC), constant power (CP), constant voltage (CV), constant resistance (CR), and rest test modes, Chroma 17011 is also equipped with waveform simulation functions and test items including DCIR, HPPC, EDLC capacitance, and EDLC DCR that comply with the international standards, so making program editing and test results analysis much easier.

The Chroma 17011 test system has flexible software editing functions embedded that can create basic charging/discharging or complex cycle tests for each channel to run independently. The program can edit logic decisions to jump or output variables, and pause or resume. It also has data protection functions to securely store the data in a nonvolatile memory in case of a power outage or disconnected communication, as to prevent potential data loss and resume the tests after reboot.

Since safety is crucial for testing lithium-ion battery cells, the design of Chroma 17011 offers a variety of safety protections. Before starting, a contact check and polarity check avoid testing under poor connection. During testing, besides the preloaded hardware circuit protection, the user can customize the firmware to detect overvoltage (OVP), overcurrent (OCP), overcapacity (OQP), voltage / current variation (ΔV / ΔI), loop resistance and other anomalies to safeguard the lithium-ion battery cells.

LINEAR CIRCUIT TEST SERIES

High precision – improving product quality

• Voltage / current measurement accuracy: ±0.015％ of F.S. / ±0.02％ of F.S.
• Wide range of voltage output: Equipped with a 0V to 6V output range, and specific models allow to switch between three built-in voltage output modes. Voltage measurements distinguished up to 0.1mV.
• Multiple range measurement design: Providing various current or voltage ranges (depending on the model) to greatly improve measurement accuracy and resolution. The current range switches automatically and at the constant voltage mode there is no current output interruption.

Fast current response – suitable for a variety of high-speed transient test applications

• Current response time (10% to 90%) < 100 μS *
• Support dynamic waveform to simulate the rapid changing current and power states

*Note: The current response time <100 μS applies to model 17216M-10-6, the impedance of other UUTs will slightly differ.

Dynamic waveform simulation

• Current and power dynamic charge/discharge waveform, simulate the actual battery usage of car driving or other real life applications
• Import the current and power waveforms from Excel file
• Save 1,440,000 points in each channel for long hour dynamic testing
• Minimalize time interval for data output: 10 mS

REGENERATIVE BIDIRECTIONAL TEST SERIES

Energy recycling – optimal utilization of electricity

• Direct recycling: Automatically transfer the discharging energy to the battery cells to be charged with recycling efficiency >80%
• Grid recycling: Recycle the excessive energy to the grid with recycling efficiency >60%
• Low carbon emissions for green energy, preventing waste heat from generating during discharge
• Saving electricity costs with high efficiency power charge and discharge
• Saving air conditioning costs on cooling equipment
• Current harmonic distortion <5% for feedback to grid current
• Power factor >0.98 at rated power

• Voltage accuracy: ±(0.02% of Reading + 0.02% of F.S.)
• Current accuracy: ±0.05% of F.S.

Fast current response – waveform mode

• Current response speed (-90%~90%) < 1mS applicable for all kinds of tests
• Support dynamic waveform to simulate the current and power state of actual car driving with NEDC, FUDS and DST test standards

FUNCTIONS

 

BATTERY DCIR TEST APPLICATION

Battery DCIR test application

The internal resistance value is related to the charge/discharge ratio of a battery. The larger the internal resistance value, the lower the efficiency when temperature rises. According to the lithium-ion battery equivalent circuit model, the ACIR measurement of traditional 1KHz LCR meters can only evaluate the conductive resistance (Ro) of the battery that affects the instantaneous power output, but is unable to evaluate the polarization resistance (Rp) produced during electrochemical reaction. The DCIR evaluation includes the ACIR that is closer to the actual polarization effect of battery under continuous power applications.

The Chroma 17011 includes two types of DCIR test modes: DCIR test (1) calculates the DCIR value using the voltage difference caused by the change of one-step current, DCIR test (2) calculates the DCIR value using the voltage difference caused by the change of two-step current. Users can select the desired test mode and automatically, without any manual calculation, get the results that comply with IEC 61960 standards.

Battery capacity test application

The capacity can be obtained as the integral of the current integrating the current versus time from the start of charging/discharging until the cut-off condition is reached. The comparison results are useful to analyze performance differences between products, and the common test items include current ratio and temperature characteristics tests. Higher accuracy of current, voltage measurement and faster sampling enable to distinguish more accurately the differences in battery cell capacity.

Battery cycle life test application

Cycle life is one of the most important test items for batteries. In accordance with the experimental purpose, it tests the same battery through repeated charge and discharge conditions until the capacity falls to 80%, and calculates the cycle numbers. The cycle life test can be used to evaluate the battery performance or define the applicable conditions of use.

Coulombic efficiency test application

Coulombic efficiency (CE) is calculated by the charge/discharge capacity ratio when the battery is fully charged and then fully discharged. Good batteries have higher coulombic efficiency, and need high precision and stable equipment to distinguish differences. An accurate coulombic efficiency test can estimate the battery lifespan with only a few cycles.

Incremental capacity analysis application

The high precision voltage measurement and ΔV sampling function can draw dQ/dV versus voltage curve diagrams to analyze battery cell characteristics and capacity degradation.

EDLC TEST APPLICATIONS

The equivalent circuit model development of the classical EDLC includes an equivalent series resistance (ESR), a capacitance (C), and an equivalent parallel resistance (EPR). The ESR is used to evaluate the internal loss and heat of the EDLC during charging/discharging; the EPR to evaluate the leakage effect in the EDLC’s long-term storage; the C to evaluate the EDLC cycle life.

These parameters are not easily directly measured in a laboratory; researchers need data analysis and complex calculations to determine these important indicators. Chroma 17011 is equipped with the IEC 62391 testing standards and the user can use charge/discharge tests to obtain the EDLC parameters values, in order to evaluate the EDLC characteristics and cycle life.

EDLC direct current resistance (DCR) and equivalent series resistance (ESR) test application

Chroma 17011 offers EDLC direct current resistance testing function compliant with test standard IEC 62391. Before testing, the EDLC has to be CV charged. The capacity test is to discharge CC via the above discharge current. When the discharge is completed, get the linear section on the discharge curve and extend it to discharge time and then get the voltage difference of rated voltage and discharge current to calculate the DCR value.

EDLC capacitance (C) test application

In accordance with the Straight Line Approximation Method of the IEC 62391 testing standard, before measuring the capacitance (C) value, the EDLC first needs to be fully charged through a CC-CV charging mode. The capacity test is to discharge CC via the above discharge current. Then, the electric potential difference (ΔV) of two reference points on the discharge curve are taken against the time difference (Δt) and the discharge current (I) to calculate the capacitance value of the EDLC.

EDLC combined DCR and C test application

Chroma 17011 also has a direct current resistance (DCR) and capacitance (C) combined test application. Under the same CC-CV charged and CC discharged conditions, the user can use the electric potential in the chosen reference points to simultaneously calculate the DCR and C values of the EDLC to save testing time.

Charge/discharge performance and cycle life test application

The built-in direct current resistance (DCR) and capacitance (C) test modes can be combined with cycle function and variable set testing conditions to test the EDLC load endurance and reliability. After testing, the user can directly export DCR vs Cycle No. and Capacity vs Cycle No. reports to analyze the EDLC failure and deterioration mechanisms.

Coulombic efficiency test application

Chroma 17011 is equipped with low noise, automatically switching current range, and cut-off report as to quickly output accurate current charge/discharge. The coulombic efficiency (CE) is calculated by the charge/discharge capacity ratio, which indicates the EDLC internal capacity conversion as available capacity. A highly accurate CE is an important marker to distinguish differences between products.

Leakage current test application

EDLC leakage current measurements generally need to CC-CV charging until a specific time and then it measures this tiny charging current, which is seen as leakage current. The Chroma 17011 CC-CV mode can automatically change current range without output interruption. Under stable voltage, the current range can be as small as 200μA.

Self-discharge test application

Chroma 17011 also has a built-in self-discharge test mode, when the EDLC is fully charged it can test the charge/discharge for a set time period. When this mode starts, the system will cut off the measuring circuit to provide the ideal open circuit and solely measure the starting potential (V1) and cut-off potential (V2). The software can automatically calculate the electric potential difference (ΔV).

GRAPHICAL SOFTWARE OPERATING INTERFACE

The Chroma 17011 test systems are controlled by computer software with diverse functions for testing energy storage products. The safe, stable and friendly operation interface allows users to perform setting and testing rapidly.

• Support English, Traditional Chinese, and Simplified Chinese languages interfaces
• Real time multi-channel DUT status monitoring
• Security management: set user authority for safe management
• Failure record tracking: independently record abnormalities for each channel, the charge and discharge protection will abort the test when an abnormal condition is detected

SYSTEM INTEGRATION

• Integrate with an environmental chamber through software to synchronize the settings conditions for charge/discharge testing
• Integrate with a multifunctional data logger through software to read and set multiple temperature records during the charge/discharge process. Change these conditions to protection or cut-off conditions

EXTERNAL STRUCTURE

Linear circuit models

The tester can be used stand-alone to take up little space, which fits a handful of tests performed on the desktop. When the tester is configured with more test channels, it can be integrated into a standard 19-inch rack for use. The system can be configured as demanded by the user as the channel numbers are expandable, and up to 64 channels can be controlled by one PC at the same time.

Regenerative models

A charge/discharge tester and an AC/DC bi-direction converter can be integrated into a standard 19-inch rack for use. The system can be configured as demanded by the user as the channel numbers are expandable, and up to 48 channels can be controlled by one PC at the same time.