Electrochemical cell analyzers, potentiostats ACK

Electrochemical cell analyzers ACK series are a powerful tool for a variety of tests of electrochemical cells, galvanic cells, accumulators, supercapacitors, and any other chemical current sources.

Page content

• General information about ACK cell analyzers
• What do ACK cell analyzers measure?
• ACK analyzers modifications
• Main parameters of ACK cell analyzers
• Cell connection and parallel operation of channelc
• Testing program
• Cell test modes
• Equivalent Series Resistance (ESR) measurement
• Measuring of capacitance of supercapacitors
• Measurement result files
• Software
• Autonomous operation of ACK analyzers
• Certificates
• Ordering ACK electrocemical cell analyzers

General information about ACK cell analyzers

Electrochemical cell analyzers ACK series tests various sources and energy storage devices, for example:

• accumulators of any type (Li-ION, Li-Po, LiFePo4, LTO, NMC, Ni-Cd, Ni-MH, Pb-Acid, as well as any others)
• supercapacitors (ultracapacitors)
• galvanic cells (primary power supplies)
• electrochemical cells
• fuel cells
• redox cells
• solar cells
• as well as any other chemical and physical sources and storages of energy.

Cell analyzers ACK series contain a controlled power supply and also a controlled electronic load. The power supply can operate in voltage, current or power stabilization modes. The load can operate in voltage, current or power stabilization modes, as well as in resistance stabilization mode.

Due to this, cell analyzers ACK series can provide a wide variety of operating modes. For example, charging, discharging, and cycling charging and discharging the battery. Testing is performed according to a very flexible test program.

Each channel of the ACK analyzer has a very wide operating range of the charge and discharge current of the cell under test. From 2.5 micro Amperes to 2.5 Amperes. Thanks to this, ACK analyzers allow testing both factory accumulators and laboratory electrochemical cells.

Cell analyzers ACK can perform many tests.

For example, the simplest, such as a single charge or a single discharge of the tested cell.

In addition, the instruments can perform cyclic tests, with multiple alternation of charge and discharge. This is relevant for cycle-life tests of cells.

Finally, cell analyzers ACK series can perform complex combination modes that simulate real-life accumulator conditions.

What do cell analyzers ACK measure?

During the tests, the ACK cell analyzers measure::

• cell charge capacity in mAh;
• cell energy capacity in mWh;
• equivalent series resistance of the cell (ESR) in Ohms;
• electric capacity of supercapacitors in Farads;
• efficiency of the charge discharge cycle in terms of capacity (by Ah) in %;
• efficiency of the discharge charge cycle in terms of energy (by Wh) in %;
• and also, average leakage current per cycle in mA.

The analyzer returns measurement results of the parameters of the tested cell in the form of text result files. In addition, software of device automatic plotts of charts of the charge discharge of the tested cell. Finally, software of analyzer automatically builds graphs of degradation of cell parameters (which is convenient, for example, during cycle-life tests).

Modifications of cell analyzers ACK

Electrochemical cell analyzers ACK series are available in several modifications:

• ACK2.5.10.1
• ACK2.5.10.2
• ACK2.5.10.8

These modifications differ only in the number of channels:

• one channel for the analyzer АCК2.5.10.1
• two channels for the analyzer ACK2.5.10.2
• eight channels for the ACK2.5.10.8 analyzer

Multichannel devices allow you to combine channels for parallel operation. The charge and discharge current of the cell under test increases in proportion to the number of parallel operating channels.

The channels of analyzers of various modifications are identical to each other.

The main parameters of the cell analyzers АCК

Each channel of the device has the following main characteristics:

• Operating voltage range: from minus 4.5 to plus 4.5 V;
• Operating range of charge and discharge current: 2.5 μA to 2.5 A.

ACK2.5.10.1

• One channel;
• Dimensions (height x width x length): 70 x 195 x 190 mm;
• Device weight: 1.5 kg (3.3 lbs).

ACK2.5.10.2

• Two independent channels;
• Maximum charge and discharge current during parallel operation of channels: 5 A;
• Dimensions (height x width x length): 120 x 182 x 202 mm;
• Device weight: 2.2 kg (5 lbs).

ACK2.5.10.8

• Eight independent channels;
• Maximum charge and discharge current during parallel operation of channels: 20 A;
• Dimensions (height x width x length): 143 x 483 x 198 mm;
• Device weight: 7 kg (15.4 lbs).

Connecting the cell to the ACK cell analyzer and parallel operation of the channels

Each channel of the ACK cell analyzers is equipped with a contact device. The analyzer contact device allows connecting cell of cylindrical shape.

The length of the tested cells can be from 0 to 70 mm, the maximum diameter is 55 mm.

In addition, any other cells can be connected to the ACK cell analyzers using wires with alligator clips. Alligator clips are supplied with the analyzers.

If the current of one analyzer channel is insufficient, adjacent instrument channels can be connected in parallel. The charge current, as well as the discharge current, increases in proportion to the number of channels.

For example, with the parallel operation of all channels of the ACK2.5.10.8 battery analyzer, you can get a charge and discharge current of 20 A.

Cell testing program on the cell analyzers ACK

Cell testing on the ACK analyzer performs according to a user-configurable test program. The test program has very flexible settings. The user configures the test program before starting the test.

The cell test program may contain:

• up to three test preparation steps performed once;
• up to 42 steps in the cyclic part of the program, executed a given number of times;
• as well as up to 3 steps of completion of the test, performed once before the end of the test.

At each step of the testing program, the ACK cell analyzer can provide the following operating modes:

• Charge with constant current;
• Discharge with constant current;
• Charge with constant power;
• Discharge with constant power;
• Charge at constant voltage;
• Discharge at constant voltage;
• Discharge at constant resistance;
• Voltage scanning;
• Current scanning;
• Rest;
• Power scanning;
• Resistance scanning;
• Current pulse mode;
• Power pulse mode;
• Resistance pulse mode;
• as well as voltage logger mode.

You can configure the repeating of the cyclic part of the testing program over a million times. Therefore, cell analyzers ACK suitable for supercapacitors cycle-life tests.

Cell test modes on the ACK analyzer

Electrochemical cells analyzers ACK can provide multiple modes of operation with the cell under test. Their variety is large enough.

Charge with constant current

designed to maintain a given charge current regardless of voltage changes. Despite the increase in cell voltage, the charge current remains constant and equal to the specified current.

The step ends in the following cases:

• when the voltage reaches a predetermined threshold
• after the specified step time has elapsed
• as well as if the voltage starts to decrease.

Charge with constant power

maintains a given charge power on the cell. As the voltage rises, the charge current will decrease in order to keep the power value at a given level.

Charge at constant voltage

designed to keep the voltage on the cell at a given level after the main charge. The step, for example, helps to complete a two-stage charge in CC – CV mode. The end of the step occurs when the current drops to a predetermined value, as well as after a predetermined time.

Discharge at constannt current

designed to maintain a given discharge current regardless of voltage. Despite the decrease in voltage, the discharge current remains constant and equal to the specified.

The end of a step occurs when the voltage decreases to a specified value, or after a specified time.

Discharge with constant power

designed to maintain the specified discharge power. As the voltage decreases, the current will increase, so the cell discharge power will remain at the specified level.

Discharge at constant resistance

designed to maintain a given cell discharge resistance. With a decrease in voltage, the current will also decrease so that the ratio of voltage and current is equal to the specified.

Discharge at constant voltage

designed to hold the voltage at a given level after discharge. In this mode, the device simulates a zener diode with a given stabilization voltage.

The end of the step occurs when the current drops to a predetermined value, as well as after a predetermined time.

Rest mode

is a pause in the test. In rest mode, the device interrupts the current flow through the cell for a specified time.

Voltage scanning mode

smoothly changes the voltage on the electrochemical cell. The voltage changes from a given start value U1 to a given end value U2 at a given rate.

You can use a combination of the two voltage scanning modes in the cyclic part of the test program. This makes it possible to investigate chemical current sources by the method of cyclic voltammetry in the mode of a potentiostat galvanostat.

Current scanning mode

smoothly changes the current through the cell. The current changes from the set start current I1 to the set end current I2 at a given speed.

The currents I1 and I2 can be either positive (charge current) or negative (discharge current). In addition, one of the current values can be zero.

Power scanning mode

smoothly changes the power on the cell. The power changes from a given initial power P1 to a given final power P2 at a given speed.

The powers P1 and P2 can be either positive (charge power) or negative (discharge power). In addition, one of the power values can be zero.

Resistance scanning mode

smoothly changes the load resistance for the cell. The resistance changes from the initial value R1 to the final value R2 at a given speed.

Current pulse mode

supplies alternating current pulses of set values I1 and I2 through the cell. The current I1 applies for the set time T1, while the current I2 applies for the set time T2.

The currents I1 and I2 can be either positive (charge current) or negative (discharge current).

The step ends when the cell voltage reaches the specified value, as well as after the specified time.

Power pulses mode

supplies alternating power pulses with preset values P1 and P2 to the cell. Power P1 applies for a given time T1, while power P2 applies for a given time T2.

The powers P1 and P2 can be either positive (charge power) or negative (discharge power).

Resistance puls mode

supplies alternating impulses of resistance of preset values R1 and R2 to the cell. Resistance R1 applies for a given time T1, while resistance R2 applies for a given time T2.

Voltage logger mode

on the cell terminals allows you to record changes in voltage over time. In logger mode, the power circuits of analyzer switchs off completely. This provides a high input impedance of the device and, therefore, a small effect on the cell under test.

The logger mode ends when the cell voltage reaches the specified value, as well as after the specified time.

Measurement of the equivalent series resistance of the cell

ACK cell analyzers are capable of measuring cell equivalent series resistance (ESR).

There are few ways for ESR measurement. The most accurate way is to interrupt the charge and discharge current with a specified period for a specified time.

This measurement mode allows you to plot the dependence of the ESR of the battery on the degree of its charge or discharge.

ESR measurement also occurs when changing pulses of current, power or resistance in the pulse modes.

In addition, ESR measurement takes place when changing steps in the testing program.

Measuring of capacitance of supercapacitors

Among other things, ACK analyzers are capable of measuring the electrical capacitance of supercapacitors, in Farads. The capacitance is measured at the constant current discharge step.

C = Ia x Δt / ΔU

Measurement result files

The end result of the work of the ACK cell analyzers are text files of the measurement results. The analyzer stores two types of result files. Several files of primary data, as well as one general file of summary measurement results.

Primary data files are saved one for each charge discharge cycle performed. If the test program requires a large number of charge-discharge cycles, you can customize results files thinning. In this case, the primary data files will be saved, for example, only for every 10th cycle.

Primary data files

contain the following parameters:

• instantaneous values of voltage (V) and current (mA) with a given step of fixing parameters in time
• instantaneous ESR values measured during charge or discharge, Ohm
• given or received capacity, mAh, cumulative from the beginning of the step
• as well as the given or received energy, mWh, cumulative from the beginning of the step.

Based on the measurement results from the primary data files, there can be:

• built charge discharge graphs of the cell
• determined the capacity and energy stored by the cell in a specific voltage range
• built graphs of cyclic voltammetry
• built graphs of ESR changes during charge and discharge
• and also built graphs of voltage, current, capacity, energy and ESR in various combinations.

Summary measurement result files

contain processed data. Each line of the summary results file describes summary data for a whole step, or for a whole cycle.

The lines of the summary measurement results file contain

• full duration of a step or cycle
• final voltage on the cell, V
• final current, mA
• average ESR per step or per cycle, Ohm
• total returned capacity, mAh
• total returned energy, mWh
• measured capacitance in Farads
• ESR values measured at the beginning of the charge, as well as at the beginning of the discharge, Ohm
• average leakage current per cycle, A
• as well as the efficiency of the cell in terms of charge and in terms of energy, %

Based on the summary measurement results, the software can generate graphs of changes in cell parameters depending on the number of charge discharge cycles passed. This is very useful, for example, for cycle-life testing of cells.

Software for cell analyzers ACK

Electrochemical cell analyzers work in connection with special software for user’s computer – Computer Interface Ys128. User should install this software on his computer.

The Ys128 software is versatile. It is suitable for working with all modifications of devices (ACK2.5.10.1, ACK2.5.10.2 and ACK2.5.10.8). We supply the software with the analyzers.

The Ys128 software contains several pages. These pages help to:

• preparing and launching a testing program
• monitoring the progress of tests
• receiving and saving measurement results
• analyzer monitoring
• as well as identifying the reasons for the abnormal termination of testing in case of its occurrence.

“Tasks” page

allows you to set up the testing program.

On the “Tasks” page for each channel you should:

• configure the parallel operation of the instrument channels (if required), then for each channel:
• select and configure the test mode for each step of the test program
• introduce protective voltage and current levels
• select the necessary modes of saving data to measurement results files
• enter cell name
• select the path to the measurement results files
• run the test with the “Start” button

“Graphs” page

displays the graphs of the charge discharge of tested cell.

Here you can see changing parameters of cell in various combinations, for example:

• voltage and current

• power and voltage

• voltage and load resistance

• ESR and voltage

• current and ESR

• voltage and charge

• voltage and energy

as well as special display modes, for example:

• dependence of voltage on the given charge

• dependence of current vs voltage, which is convenient when testing a sample by the method of cyclic voltammetry

“Results” page

allows you to observe the formation of files of measurement results.

“Analysis” page

displays graphs of changes in battery characteristics depending on the number of completed charge discharge cycles.

СтраниThe page allows you to visually observe the change in the characteristics of the battery during cycle-life tests.

“Settings” page

is intended for setting up the connection between the computer and the cell analyzer ACK. Also, the “Settings” page is used to calibrate the device in the factory.

Among other things, the Yp1 software allows you to open and view results files obtained in the past. After opening the files, the software automatic plots of the charge discharge charts, as well as degradation charts.

Historical graphs can be displayed in addition to real-time graphs. This allows you to visually compare the graphs for real-time tested cells with some “reference” graphs for “reference” cells.

Viewing historical files is possible, including in the Off-line mode, without connecting to the device.

Autonomous operation of cell analyzers АСК

The ACK cell analyzers have built-in memory. The memory halps to save the measurement results in case the connection with the computer becomes temporarily unavailable.

When the connection is restored, the analyzer transfers all the accumulated data to the computer. Then the Yp1 software saves the data to the files of the measurement results.

As a result, the built-in memory enables the cell analyzer to operate autonomously for some time after starting the test. This allows you to turn off your computer at night, as well as on weekends or holidays.

Certificates

Ordering cell analyzers

To order ACK cell analyzers, send a request to the email address Yarstst@gmail.com

We supply cell analyzers under a supply contract.

The cost, as well as the delivery time, depends on the required number of devices.