Metrohm Autolab Operating and installation instructions

Autolab/
Electronic Load
Installation Description
Picture Courtesy of Nedstack Fuel Cell Technology BV

Autolab/Electronic load combination
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Autolab/Electronic load combination
The Autolab range of instruments is limited in terms of maximum current or power
that can be supplied to or extracted from an electrochemical cell. When working
with high power energy storage or energy conversion devices, the power
requirements can often exceed those available with a normal Autolab PGSTAT,
even when it is extended with a Booster 10A or 20A.
To meet these experimental requirements, the Autolab can be easily combined
with a third-party programmable electronic load.
Modern electronic loads are capable of reaching over 100 A easily. This
combination therefore extends the measurable range of the Autolab by decades of
current or more.
When the Autolab is combined with an electronic load, the load will sink the
current while the Autolab will measure the voltage across the electrochemical cell.
The combination of the Autolab and the electronic load requires the dedicated
DYNLOAD interface (Article code: LOAD.INT).
Using the DYNLOAD interface, several types of measurements are possible:
•DC measurements at high current densities (up to the maximum current
allowed by the load).
•Electrochemical impedance spectroscopy measurements at high current
density (up to the maximum current allowed by the load).
Most electronic loads can be controlled in four operation modes:
•
Constant current (CC) mode
1
:
current is drawn from the cell until the
specified current value is reached.
•
Constance voltage (CV) mode:
current is drawn from the cell until the cell
voltage reaches a specified value.
1This installation note only covers this operation mode. Please contact Metrohm Autolab for more
information on the other modes ([e-mail]).
Note
It is also possible to combine the Autolab with a programmable power supply.
In this case, the power supply will be used to source high currents to the cell
and the Autolab is used to control the voltage across the cell. The use of a
programmable power supply is not specifically covered in this manual. More
information can be obtained by contacting Metrohm Autolab (info@metrohm-
autolab.com).

Autolab/Electronic load combination
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•
Constant power (CP) mode:
current is drawn from the cell until the
output power reaches a specified value.
•
Constant resistance (CR) mode:
current is drawn from the cell until the
resistance to the current flow reaches the specified value.
The
constant current
(CC)
mode is the most suitable for the combination with the
Autolab, however the other modes are also available but these modes are affected
by ohmic losses and are therefore not accurate.
Warning
When the Autolab is combined with an electronic load, the Autolab will only be
used to control the load and measure the cell voltage. The specifications of the
Autolab are therefore irrelevant for this application and only the specifications
of the electronic load must be selected carefully (see Section 1). The Autolab
PGSTAT204/FRA32M is suitable for all the measurements described in this
manual.

Autolab/Electronic load combination
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Table of Contents
1 – Choice of the electronic load....................................................................... 5
2 – Dynload interface part list ........................................................................... 6
3 – Autolab part list .......................................................................................... 8
4 – Electronic load part list ................................................................................ 9
5 – Polarity convention.................................................................................... 10
6 – Connections to the Dynload interface ....................................................... 10
6.1 – Connections without a FRA module .................................................. 10
6.2 – Connections with a FRA32M module ................................................ 12
6.3 – Connections with a FRA2 module...................................................... 13
7 – Connections to the cell.............................................................................. 14
7.1 – Connections for cell voltages ≤ 10 V ................................................. 14
7.2 – Connections for cell voltages > 10 V ................................................. 15
7.2.1 – Voltage multiplier part list.......................................................... 15
7.2.2 – Connections to the instrument................................................... 16
8 – Electronic load settings.............................................................................. 17
8.1 – Programming the load (TDI) .............................................................. 18
8.2 – Programming the load (Kikusui) ........................................................ 19
8.3 – Controlling the electronic load .......................................................... 20
8.3.1 – Controlling the electronic load (TDI)........................................... 20
8.3.2 – Controlling the electronic load (Kikusui)..................................... 20
9 – NOVA hardware setup .............................................................................. 21
9.1 – Analog input settings ........................................................................ 22
9.2 – Analog output settings...................................................................... 23
10 – Manual control of the electronic load (DC only)....................................... 24
11 – Procedure control of the electronic load (DC only)................................... 27
12 – Recording the output from the electronic load (DC only)......................... 30
13 – Impedance spectroscopy measurements ................................................. 33
13.1 – External settings.............................................................................. 35
13.1.1 – Settings for V ...................................................................... 35
13.1.2 – Settings for X ...................................................................... 36
13.1.3 – Settings for Y ...................................................................... 36
13.1.4 – Settings for Transfer function................................................... 37
13.2 – Frequency scan settings .................................................................. 38
13.3 – Sampler settings.............................................................................. 39
13.4 – Plots settings................................................................................... 41
13.5 – Running a measurement ................................................................. 42
14 – Measurement examples .......................................................................... 44
14.1 – iV/Power curve................................................................................ 44
14.1.1 – Running the measurement....................................................... 44
14.2 – Impedance spectroscopy measurement........................................... 45
Appendix 1 – Specifications of known electronic loads ................................... 48
Appendix 2 – Modification of the FRA2 module.............................................. 49

Autolab/Electronic load combination
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1
– Choice of the electronic load
The electronic load is a critical component of this hardware setup and it should be
chosen carefully. Some electronic loads are more suitable for working with a low
power energy storage device, while other electronic loads are adapted to very
large power output systems.
Many commercially available electronic loads can be used in combination with the
Autolab PGSTAT. However, in order to operate in combination with the PGSTAT,
the electronic load must fulfil the following requirements:
•Analog external programming to control the setpoint (0-10 V range)
•Analog external current monitor for current readout (0-10 V range)
A list of compatible electronic loads can be found in Table 1.
Load
Application
Bandwidth
Kikusui PLZ164WA
Single cells 100 kHz
Kikusui PLZ664WA
Single cells, small stacks 100 kHz
TDI RBL 488
Medium stacks 20 kHz
TDI WCL 488
Large stacks 1 kHz
Agilent 6060B
Single cells, small stacks 20 kHz
Agilent 3300
Single cells, small stacks 20 kHz
Chroma 6300
Medium stacks 20 kHz
Table 1 – Overview of compatible electronic loads
For small energy storage devices, a low power electronic load is sufficient. For
larger devices, more powerful electronic loads are required. Some electronic loads
require active cooling for power dissipation.
As a rule, it is not possible to have the following specifications at the same time:
•Full current output even at 0 V cell voltage
•High bandwidth (> 1 kHz)
•High power
Small electronic loads like the Kikusui PLZ164WA have very high bandwidth
ratings and can operate at maximum current even if the cell voltage is 0 V. The
maximum power of these loads is however limited, which means that these
instruments are suitable for small single cell systems. On the other hand, larger
loads like the TDI RBL 488 have high maximum power and sufficient bandwidth,
but they require a minimum cell voltage to operate at full power (for example, the
TDI RBL 488 requires 3 V DC voltage to operate at 300 A, as shown in Figure 1).
These systems are therefore more suitable for large stacked cells.

Autolab/Electronic load combination
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Figure 1 – Contour map of the TDI RBL 488
2
– Dynload interface part list
The Dynload interface kit includes the following items:
1. The Dynload interface (see Figure 2).
2. 15 V power supply
3. A 2 m long BNC cable
4. A 50 Ω terminator plug
5. 6 BNC to SMB adaptor plugs
6. 3 SMB shielded cables (1 m)
7. A BNC splitter
Note
A special Dynload interface version suitable for the Electronic loads supplied by
the Japanese brand Kikusui is available on request (see Figure 2). This version is
only suitable for the Kikusui loads.

Autolab/Electronic load combination
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Figure 2 – Two versions of the Dynload interface (left – general purpose interface, right – for
Kikusui electronic loads)
The three SMB shielded cables can be fitted with SMB to BNC adaptor plugs.
Depending on the type of FRA module used in combination with the LED Driver,
these cables can be modified accordingly:
•For the FRA2 module, the cables must be fitted with SMB to BNC adaptors
on both ends (see Figure 3).
Figure 3 – Configuration of the SMB cables used in combination with the FRA2 module
•For the FRA32M module, the cables must be fitted with SMB to BNC
adaptors on a single end (see Figure 4).
DYNAMIC LOAD
External prog.DAC-1
DSG
Y-FRA/ADC
I-M
15 V
+
-
To back panel of electronic load
DYNAMIC LOAD
DAC-1
DSG
Y-FRA/ADC
Dynamic load
15 V
+
-
Dynload FRA Y 
Dynl DSG FRA V
E-out FRA X 

Autolab/Electronic load combination
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Figure 4 - Configuration of the SMB cables used in combination with the FRA32M module
3
– Autolab part list
The Autolab PGSTAT is used as a voltmeter in combination with the electronic
load. This means that the WE and CE connectors provided by the Autolab
must
not
be connected to the cell.
The monitor cable is required for the combination with the electronic load and it
must be attached to the front panel of the PGSTAT (see Figure 5).
Dynload FRA Y 
Dynl DSG FRA V
E-out FRA X 
Warning
Never connect the WE/CE connectors of the Autolab to the electrochemical cell
when working in combination with an electronic load. High currents can
damage the Autolab!
Note
The monitor cable for the PGSTAT204 is not supplied with the instrument and it
must be ordered separately. Please contact [e-mail] for
more information.

Autolab/Electronic load combination
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Figure 5 – Monitor cable for the PGSTAT204 (above) and
the Series 8 PGSTAT128N/302N (below)
4
– Electronic load part list
The electronic load must be connected to the electrochemical cell using cell cables
suitable for the expected power drawn from the cell. It is recommended to use
thick cables with very low resistivity to avoid ohmic losses.
Additionally, the cables required to connect the Dynload interface to the
programming port of the electronic load must be sourced by the end user. The
type of cables required depends on the type of electronic load. The connections to
the Dynload interface must be BNC.
PGSTAT204
PGSTAT128N/302N
Note
Please refer to the user manual of the electronic load for more information on
the connection requirements or contact Metrohm Autolab (info@metrohm-
autolab.com) for assistance.

Autolab/Electronic load combination
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5
– Polarity convention
The NOVA software, used to control the Autolab and the electronic load
connected to it, uses the IUPAC convention for potential and current polarity.
Charging (or anodic) currents are indicated with a positive sign. Discharging (or
cathodic) currents are indicated with a negative sign.
For this application, working with an electronic load to discharge energy storage
or conversion devices, cell voltages will be positive and discharge currents will be
negative.
The software can be adjusted to account for this polarity convention.
6
– Connections to the Dynload interface
This section describes the connections required to perform the measurements with
the Autolab in combination with an electronic load. The connections depend on
the instrument type and configuration. In the rest of this document, an N series
Autolab instrument is used, however other instrumental configurations are
possible.
6.1
– Connections without a FRA module
If no FRA module is present in the instrument (FRA2 or FRA32M), the connections
between the Autolab and the Dynload interface should be as described in Figure
6.
Note
The current indicated on the front panel of the electronic load will be positive.

Autolab/Electronic load combination
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Figure 6 – Connections overview without FRA module
1. Connect the DAC164 output one on the front panel of the Autolab
(DAC164 1) to the DAC-1 input of the Dynload interface.
2. Connect the Y-FRA/ADC output of the Dynload interface to the ADC164
input one on the front panel of the Autolab (ADC164 1).
3. The DSG input of the Dynload interface
must be shorted
with the provided
50 Ohm termination plug (see Figure 7).
Figure 7 – A 50 ohm terminator plug must be used to short the DSG input when this input is
not used
DYNAMIC LOAD
External prog.DAC-1
DSG
Y-FRA/ADC
I-M
15 V
+
-
50 Ω
Note
Make sure that the 50 Ohm plug is connected to the DSG input at all times!

Autolab/Electronic load combination
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6.2
– Connections with a FRA32M module
If a FRA32M module is present in the instrument, the connections between the
Autolab and the Dynload interface should be as described in Figure 8.
Figure 8- Connections with the FRA32M module
1. Connect the DAC164 output one on the front panel of the Autolab
(DAC164 1) to the DAC-1 input of the Dynload interface.
2. Connect the Y-FRA/ADC output of the Dynload interface to the ADC164
input one on the front panel of the Autolab (ADC164 1) and using the
provided BNC splitter, connect the same signal to the FRA32M Y input.
3. Connect the Eout signal, provided by the monitor cable to the FRA32M X
input.
4. Connect the FRA32M Voutput to the DSG input on the Dynload
interface.
DYNAMIC LOAD
External prog.DAC-1
DSG
Y-FRA/ADC
I-M
15 V
+
-
Eout
Iout
Ein
Note
For the PGSTAT204, use the Vout and Vin provided by the monitor cable
instead of DAC164 1 and ADC164 1, respectively.

Autolab/Electronic load combination
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6.3
– Connections with a FRA2 module
If a FRA2 module is present in the instrument, the connections between the
Autolab and the Dynload interface should be as described in Figure 9.
Figure 9 – Connections with the FRA2 module
1. Connect the DAC164 output one on the front panel of the Autolab
(DAC164 1) to the DAC-1 input of the Dynload interface.
2. Connect the Y-FRA/ADC output of the Dynload interface to the ADC164
input one on the front panel of the Autolab (ADC164 1) and using the
provided BNC splitter, connect the same signal to the FRA2 Y input.
3. Connect the Eout signal, provided by the monitor cable to the FRA2 X
input.
4. Connect the FRA2 Voutput to the DSG input on the Dynload interface.
DYNAMIC LOAD
External prog.DAC-1
DSG
Y-FRA/ADC
I-M
15 V
+
-
Eout
Iout
Ein
Note
For the PGSTAT204, use the Vout and Vin provided by the monitor cable
instead of DAC164 1 and ADC164 1, respectively.

Autolab/Electronic load combination
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7
– Connections to the cell
The electronic load (+) is connected to the (+ or cathode) of the cell, and the
electronic load (-) is connected to the (- or anode) of the cell.
7.1
– Connections for cell voltages ≤ 10 V
The S and RE cables of the Autolab differential amplifier are connected to the cell
under study. The S is connected to the (+) and the RE connected to the (-). The CE
and WE connections of the PGSTAT are not used.
Warning
Analog programming of the electronic load requires a modification of the FRA2
module to accept analog signal up to 10 V. A hardware and software
modification may be required. More information is provided in the Appendix 2.
Please contact Metrohm Autolab ([e-mail]) or your local
distributor in case of any doubts.
 = 
Warning
The cables connecting the electronic load to the cell must have the lowest
possible resistance and should be able to withstand high current densities.
Keep in mind that ohmic losses cannot completely be avoided. Most electronic
loads have a
voltage reversal detection
circuit which monitors the cell voltage
and shuts down the load when this value becomes negative or lower than a
threshold. For electronic loads that are unable to operate at low cell voltages,
the maximum current that can be drawn from the cell may be affected by
ohmic losses.
Because of ohmic losses, the apparent voltage measured by the load,  is
always smaller than the voltage measured by the Autolab () by a value
equal to the product of and , where is the total resistance of the cables:
Passing 80 A through 10 mΩ cables, leads to 800 mV ohmic drop.
Warning
Never connect the CE and WE from the Autolab PGSTAT to the cell!

Autolab/Electronic load combination
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7.2
– Connections for cell voltages > 10 V
The input range of the Autolab differential amplifier is limited to 10 V. When the
cell voltage is larger than 10 V, for example when measuring on large cell stacks,
the input voltage of the Autolab can be extended to 100 V by using the
Voltage
multiplier
(Item code: VOLT.MULT).
7.2.1 – Voltage multiplier part list
The Voltage Multiplier kit includes the following items:
1. The Voltage Multiplier box (see Figure 10)
2. A red 30 cm long male banana to banana cable
3. A blue 30 cm long male banana to banana cable
Note
It is recommended to connect the RE and S leads from the PGSTAT as close as
possible to the cell.
Important restriction
The Voltage Multiplier reduces the
input impedance
of the PGSTAT
electrometer to ~ 100 kOhm. Only use the Voltage Multiplier when the total
impedance of the DUT is very low with respect to the input impedance
(typically, 100 Ohm or less).

Autolab/Electronic load combination
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Figure 10 – The Voltage Multiplier
7.2.2 – Connections to the instrument
Connect the voltage multiplier to the differential amplifier. Connect the Sense lead
to the S-Pgstat connector and the Reference lead to the RE-Pgstat connector on
the voltage multiplier.
The voltage multiplier provides two connections to the DUT. Connect the S-Cell
connector to the WE banana connector of the PGSTAT and the positive pole of the
DUT using the provided additional red cable. Connect the RE-Cell connector to the
CE banana connector of the PGSTAT and the negative pole of the DUT using the
provided additional blue cable (see Figure 11).
RE-Pgstat
VOLTAGE MULTIPLIER
RE-cell
R4
90kΩ
S-PgstatS-cell
R1
90kΩ
R3
10kΩ
R2
10kΩ

Autolab/Electronic load combination
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Figure 11 – Wiring diagram of the voltage multiplier between the DUT and the PGSTAT
8
– Electronic load settings
Before the measurements can be performed, it is mandatory to program the
electronic load. Please refer to the user manual provided with the electronic load
for more information or contact Metrohm Autolab B.V. for setup guidelines
([e-mail]).
Most electronic loads have a number of common settings which have to be
considered:
•
External control (ON/OFF):
all electronic loads have a switch which
activates or deactivates the external programming capability. This switch
must be set to ON.
+-
Differential amplifier
SRE
GND
SRE
+-
Voltage multiplier
Differential amplifier
SRE
GND
SRE
Warning
Connect the green ground cable from the PGSTAT to the GND connector on
the voltage multiplier! The ground cable must be connected to the voltage
multiplier at all times.

Autolab/Electronic load combination
18 | Page
•
Bandwidth, Slew rate:
on some devices, the bandwidth or the slew rate
can be set manually. If this is the case, the highest possible value should be
used.
•
Mode (CC, CV, CP, CR):
all electronic loads have four operation modes:
constant current (CC), constant voltage (CV), constant power (CP) and
constant resistance (CR). For this application, the constant current mode
(CC) is required for this application.
•
Voltage and current range:
some electronic loads provide different
voltage and current ranges, which have to be set according to the
experimental conditions.
•
Cell switch:
all electronic loads have a manual cell switch which must be
set ON before the measurement starts.
8.1
– Programming the load (TDI)
Figure 12 shows the overview of the front panel of the TDI RBL 488 series.
Figure 12 – Front panel of the TDI RBL 488 series
Follow these steps to ensure that the load is setup correctly for this application:
1. Switch on the TDI load.
2. Set the instrument to constant current mode by pressing the CI button.
3. Select the voltage range and the current range of the instrument by
pressing the corresponding buttons. Set the active current range to the
highest available (300 A for the RBL 488 100 – 300 – 2000).
4. Activate the external programming of the load by pressing the EXT PROG
button.

Autolab/Electronic load combination
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8.2
– Programming the load (Kikusui)
Figure 13 shows the overview of the front panel of the Kikusiu PLZ164WA.
Figure 13 – Front panel of the Kikusiu PLZ164WA
Follow these steps to ensure that the load is setup correctly for this application:
1. Switch on the Kikusui load.
2. Press
SHIFT
key and
SET/VSET
key on the front panel.
3. Using the rotating knob, highlight the Configuration menu item and press
the
ENTER
key.
4. Using the rotating knob, highlight the External menu item and press the
ENTER
key.
5. Using the rotating knob, set change the Control menu item to
V
and the
LoadOn In item to
HIGH.
6. Press the
SHIFT
and
SET/VSET
keys to return to the main menu.
7. Press the
RANGE
key to cycle through the different current ranges and set
the active range to the highest available (33 A for the PLZ164WA).
8. Press the
MODE
key to cycle through the different operation modes and
make sure that the constant current mode (CC) is selected.
9. Press the
SLEW RATE
key and adjust the slew rate to the highest possible
value, using the rotating knob.
10. Switch the load off and then on again to confirm the changes.

Autolab/Electronic load combination
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8.3
– Controlling the electronic load
The control of the electronic load is achieved by providing an analog (0-10 V)
signal from the Dynload interface to the external programming connection of the
load.
The output of the Dynload interface in turn is controlled by the output of the
DAC164 1 of the Autolab and the FRA2/FRA32M Voutput, if applicable.
The conversion settings depend on the type of load and are specified in the
software.
8.3.1 – Controlling the electronic load (TDI)
The TDI RBL 488 (100 V, 300 A, 2000 W) is an electronic load with a maximum
voltage of 100 V and a maximum current of 300 A.
If the load is in constant current (CC) mode, with the 300 A current range
selected, the conversion will be:

=10 
300 =0.03333 /
With a 0 V analog signal from the PGSTAT, the load will operate at 0 A. With a 10
V analog signal from the PGSTAT, the load will operate at 300 A.
The same conversion is used for the current readout. The electronic load has an
analog output corresponding to the measured current. The range of the current
monitor analog signal is 0-10 V, which corresponds to the range of 0 A to
maximum current, which depends on the selected current range of the electronic
load.
The TDI RBL 488 (100 V, 300 A, 2000 W) is an electronic load with a maximum
voltage of 100 V and a maximum current of 300 A. Operating in the 300 A current
range, the current monitor conversion factor will be:

=300 
10 =30 /
With 0 V output voltage measured on the current monitor, the current drained by
the electronic load is 0 A. When 10 V output voltage is measured, the current
drained by the electronic load it the maximum value of 300 A.
8.3.2 – Controlling the electronic load (Kikusui)
The Kikusui PLZ164WA (150 V, 33 A, 165 W) is an electronic load with a
maximum voltage of 150 V and a maximum current of 33 A. The maximum power
is 165 W.