EV Battery Testing Equipment | Battery Energy Storage System Tester

EV Battery Testing Equipment

Battery Energy Storage System Tester 

Functional description:

The battery system tester is an energy feedback type EV battery testing equipment and battery energy storage system tester with powerful test functions.

The battery system tester can provide diverse outputs, such as constant voltage, constant current, constant current converting to constant voltage, pulse, constant power, constant resistance, current phase step, voltage ramp, current ramp and variable power modes etc.; in the meantime, any steps can be programmed to operate in any combination of operating modes to execute charge/discharge test and the modes can be switched quickly.

Applicable range:

The battery system tester is specially designed to test the high-power secondary battery packs, such as EV battery packs and battery energy storage systems, etc.

The battery system tester can execute variable power curve output at the millisecond level and carry out battery simulation test according to the real use condition of the battery pack with excellent accuracy and flexibility.

Features: 

1) Energy-feedback design

With high energy-feedback efficiency, the discharged energy can return to the power grid or be used by the battery system tester, which saves power.

2) Execute working condition simulation test according to the actual use conditions

The actual working condition data of the battery system can be transformed to the simulation test technology so that the users can develop their own test working conditions.

3) User-friendly operational software

3.1) With simplified operational software, the battery system tester integrates "working condition simulation" and "charge-discharge function".

3.2) The battery system tester has diverse outputs ("step design"), such as constant current, constant voltage, constant current converting to constant voltage, pulse, constant power, constant resistance, current phase step, voltage ramp, current ramp, variable power, cycle and rest etc.

3.3) Test step: ≥9999 steps; cycle index: ≥9999 times; unlimited program storage.

3.4) Set the jump and end conditions according to the conventional variables (voltage, current, time, capacity, energy, power and temperature) and custom variables (BMS variables and other collectors).

3.5) The battery system tester & working condition simulation system adopts “menu-type programming”. It supports real-time working condition file (EXCEL format) import. The working condition files can be obtained by artificial editing and working condition acquisition system.

4) Data report

4.1) Data report function: XLS-format report can be generated. The report includes channel data, step data, result data, real-time data etc and the report can be converted into graphs.

4.2) Data analysis function: the user can simultaneously select 4 parameters on Y axis and thus generate the needed graphs.

4.3) Data storage: the data can be exported one by one or all exported by multiple choices; the data can be named by barcode No., administrator ID or item name etc.

5) Sophisticated protection functions

5.1) Sophisticated input and output power-off protection function can ensure the security of the battery system tester, test data and test objects. Flexible programming modes can meet the test requirements of the complex techniques.

5.2) Input protection: overvoltage, overcurrent, default phase and over-temperature protection.

5.3) Output protection: overvoltage, overcurrent, short-circuit, temperature, undervoltage, battery polarity reversal and external short-circuit protection.

5.4) Power-off protection: after power off, the battery will disconnect from the battery system tester.

5.5) Battery cell protection: cell undervoltage, cell overvoltage, cell overtemperature and reversed polarity protection. The protection limit value can be set.

5.6) The control software can set the protection conditions: software overvoltage protection, software undervoltage protection, software overcurrent protection, auxiliary temperature protection, auxiliary voltage protection. The protection voltage and current values can be set, displayed, prompted and recorded on the list after channel protection.

5.7) Emergency-stop protection: under abnormal situations, the battery system tester has emergency stop function. All the channels can be stopped simultaneously.

6) Output of a single channel

The high-power battery pack working condition simulation test system contains 2 channels. Each channel is composed of a 1000V800A bidirectional DC/DC power. The max. power of each channel is 250kW.

7) Parallel-connected channels extend the application scope

7.1) The battery system tester is composed of 2-channel 1000V800A power systems and the 2 channels can be used in parallel to realize the 1600A output.

7.2) The flexible parallel connection of multiple channels helps users reduce the device investment.

8) System integration

Integration of liquid-cooling system, vibrostand, environment chamber, cell voltage & temperature acquisition system and electronic load braking system etc (the integrated equipment should be charged):

8.1) After integrating with constant temperature and humidity chamber via the software, the battery system tester can execute synchronous set-up conditions matching with cycling test and reserve RS232, CAN and Internet interfaces.

8.2) After integrating with cell voltage and temperature acquisition system, via software, the battery system tester can collect and analysis the Li-ion battery cell temperature in real time and reserve CAN and Internet interfaces.

Test items:

1) Contrast of parameters in some BMS addresses.

2) Accuracy test of BMS static total voltage

The sampling comparison of BMS and the battery system tester.

3) Current accuracy test of BMS sampling

The comparison of current measured by BMS and the battery system tester.

4) DCIR

Can be added according to the requirements of users.

According to BS EN 61960, the following test waveform can be used and the DCIR value can be calculated by the voltage difference.

Compute mode 1: apply one current pulse on the two poles of the battery, then the terminal voltage of the battery will change suddenly. Here, in the DCIR formula: ΔI is the current pulse; U (t) is the terminal voltage at t (time); U0 is the original terminal voltage. In most cases, DCIR includes ohmic IR and partial polarization IR. Therein, the proportion of polarization IR will be affected by the current loading time t.

Compute mode 2: change the current on the two terminals of the battery, then the terminal voltage will also change. In the DCIR formula: ΔI is the current change; ΔU is the voltage change.

5) Cycle life test of battery module/pack

The battery charge discharge test is required for all the batteries. In this test, the evaluator will repeatedly test one same battery according to the defined charge-discharge conditions. Then count how many periods the battery has gone through until access to the end conditions of the test. The counted periods are the cycle periods of the battery. The more the cycle periods are, the longer the service life is. After that, test different kinds of batteries according to the same test conditions so as to evaluate the quality of the batteries or the most suitable charge-discharge and working conditions of a certain battery.

6) Capacity test of battery module/pack

In most cases, the measurement of battery module/pack capacity is affected by the discharge current and time. Though every battery has a specification provided by the manufacturer and its capacity test will be conducted with low charge-discharge rate, the power battery should be charged and discharged with high charge-discharge rate. If set the battery capacity according to the provided specification, there will be some deviation with the actual capacity. Therefore, the battery cell should be tested according to the final charge-discharge rate of the power battery so as to get a more accurate capacity.

7) Charge/discharge test of battery module/pack

Li-ion battery often adopts the charging mode of constant current converting to constant voltage. At the beginning, the battery voltage is low and the charge current is constant, viz. constant current charge. Then the battery voltage rises to 4.2V gradually and the charger switches to the constant voltage charge. The fluctuation of the charge voltage should be kept within 1% and the charge current reduces gradually. When the current decreases to a certain range, here comes the trickle charge, viz. maintenance charge. Under the state of maintenance charge, the charger will keep charging with a certain charge rate until the charge completes.

With different discharge rate, the battery voltage changes greatly. The larger the discharge rate is, the lower the battery voltage of the corresponding surplus capacity is. If the discharge rate is 0.2C, the rated capacity will be discharged when the battery cell voltage decreases to 2.75V. If the discharge rate is 1C, 98.4% of the rated capacity will be discharged.

8) Pulse charge/discharge test of battery module/pack

It is well known that the diffusion rate of the Li-ion battery between the two poles decides the charging speed of the Li-ion battery. If the diffusion rate is too slow, the concentration polarization will be caused, especially in the charging process of large current. On account of concentration polarization, the terminal voltage of the battery will rise to the charge end voltage rapidly.

On conquering these difficulties, we applied pulse charging technology into the Li-ion battery, viz. inserting idle time and discharge pulse into the charging process. The idle time and discharge pulse can effectively eliminate the concentration polarization and increase the power transmission rate. In this way, the use ratio of the active materials can be enhanced and the charging time can be shortened.

9) Charge retention and recovery capability test of battery module/pack

In the charge retention and recovery capability test, the capacity retention status can be measured after the Li-ion battery has been stored for some time. After the charge retention test, recharge the battery and measure the capacity recovery status according to a certain test procedure.

10) Charge-discharge efficiency test of battery module/pack

The running cost and service life of the battery module/pack are closely related to its power performance. So, it is very necessary to study the charge-discharge efficiency of the battery pack so as to build up an optimal charge-discharge performance model, shorten the charging time, increase the released energy and ensure the stored energy can meet the requirements of the vehicle during its whole service life.

The charging efficiency is decided by the charging system and the discharge depth of the battery before charging, while the discharge efficiency is related to the total resistance loss and discharge current.

11) Consistency test of battery module/pack

There are some problems in the application of power batteries in EV power systems, such as durability, reliability and safety etc. One of the main reasons for these problems is the inconsistency of battery cells.

The inconsistency of power batteries mainly displays on the discrepancy of the battery cell performance parameters and the working status. The former one includes the differences on battery capacity, internal resistance and self-discharge rate; the latter one is the difference on the charging state and the working voltage.

12) Temperature test of battery cell

The capacity of the Li-ion battery will be influenced by different temperatures. Under the same charge-discharge condition, the higher the temperature is, the larger the capacity is. On the contrary, the lower the temperature is, the lower the capacity is.

Technical specifications