ZAHNER EL1002 User manual

Electronic
Load
EL1002
(Operation Manual)
24/07/2023

Electronic Load – EL1002

Electronic Load – EL1002
1 Electronic load EL1002 ............................................................................. 4
1.1 Packing List.......................................................................................... 4
2 Caution.......................................................................................................5
3 Introduction................................................................................................7
3.1 Modular concept – extension to ZENNIUM series potentiostat........7
3.1.1 EL1002 electronic load ...................................................................7
3.1.2 EPC42 controller card....................................................................8
3.2 Stand-alone mode.............................................................................. 9
4 Operation basics......................................................................................10
4.1 Signals & connections........................................................................10
4.1.1 Conductor rails ...............................................................................11
4.1.2 Safety interlock............................................................................. 12
4.1.3 Signal LEDs & buzzer ................................................................... 12
4.2 Operation steps.................................................................................13
5 Thales software .......................................................................................15
6 Cell connection fundamentals ................................................................18
6.1 Contact resistance.............................................................................18
6.2 Four-electrode cell connection scheme..........................................19
6.3 Two-electrode cell connection scheme ......................................... 20
6.4 Parasitic inductances........................................................................21
7 Connection configurations..................................................................... 24
7.1 Applications for the EL1002 without external devices.................... 25
7.1.1 Full cell configuration (standard Kelvin scheme) ......................25
7.1.2 Half-cell configuration – Cathode...............................................27
7.1.3 Half-cell configuration – Anode ..................................................27
7.1.4 Partial cell configuration ..............................................................28

Electronic Load – EL1002
7.2 General notes for applications with external supply or load.......... 29
7.3 Applications with an additional DC load...........................................31
7.3.1 DUT connected to the EL1002 with an additional DC load
through EXT+.......................................................................................... 31
7.3.2 DUT connected to the EL1002 with a parallel DC load.......... 33
7.4 Applications with an additional power supply in series.................. 35
7.4.1 Electrolysis / charging batteries .................................................35
7.4.2 Compensation for voltage drop (zero-volt option)..................37
7.5 Applications with an additional power supply in parallel using the
EXT+ terminal.......................................................................................... 39
7.5.1 Charging........................................................................................ 40
7.5.2 Discharging ................................................................................... 41
7.5.3 State of charge (SoC)..................................................................42
7.5.4 Summary parallel power supply with PAD4............................. 43
8 Specifications ......................................................................................... 44
8.1 Ranges and tolerances..................................................................... 44
8.2 General specifications...................................................................... 45
8.3 Safe operation conditions................................................................ 46

Electronic Load – EL1002 -4-
1Electronic load EL1002
Zahner products are carefully manufactured, calibrated and tested to ensure our
high-quality standard. Packing of the electronic load EL1002 and accessories is done
with great care to avoid damage during transport. Upon receipt of the Zahner
shipment, please check the device and accessories to make sure they are intact. If
a product is damaged during shipment, please immediately contact your Zahner’s
service partner.
1.1 Packing List
•EL1002
•EPC42 cable
•Sense cable (Lemosa plug to blue & green twisted cables)
•USB cable
•Power cord
•USB Stick:
oCalibration report
oCalibration data
oThis manual (pdf)
•Zahner Analysis license key
•This manual

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2Caution
Please read the risk assessment document before operating the potentiostat.
Prevent the inputs of the potentiostat from electrostatic discharge (ESD)! ESD may
damage the potentiostat. ESD-related damages are not covered by the warranty of
the potentiostat. The user must make sure to discharge themselves from any
electrical charge before touching the potentiostat (TIP: use grounded ESD-matts).
Zahner’s potentiostats require a warm-up time of 30 minutes for optimum
performance.
Do not leave the active objects such as batteries or fuel cells connected to the power
outputs of the potentiostat when the potentiostat is switched off! This may damage
the potentiostat.
To drive high currents with an EL1002, the customer must use a cable set
recommended for high current applications and fasten it to the terminals with
suitable cable lugs.
Pay attention to the cable connection schemes and strictly follow the guidelines of
this manual. A connection scheme with reversed polarity may damage your device.
During operation, the potential directly on the positive (+) terminal of the EL1002
should be at least 1 V higher than the negative (–) terminal.
Always turn ON the EL1002 after turning on the external load or the external power
supply (if any is connected).
No current should flow through the EL1002 immediately after turning on the EL1002.
No current should flow through the EL1002 immediately after selecting the EL1002
in Thales software until the startup calibration is finished.
Always turn OFF the EL1002 prior to turning OFF the external load or the external
power supply (if any is connected).
Properly fasten the EPC42 cable with the EL1002 using screws. Accidental
unplugging of the EPC42 cable during operation may damage your device.
When working with high currents, remove all metallic jewelry/watches which can
possibly create short circuits.

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Don’t touch the electrical connections during operation.
Never expose potentials higher than 100 V to the EL1002.
The maximum current through the positive (+) terminal of EL1002 must never exceed
200 A.
The maximum current through the shunt/current measurement unit of the EL1002
must never exceed 680 A.
The current cables from EL1002 to the test object must be as short and thick as
possible.
During EL1002 start up and calibration, do not sink external DC current.

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3Introduction
Zahner’s electronic load EL1002 can be used as an extension to the ZENNIUM series
potentiostat or in a stand-alone configuration. In the following sections, both
scenarios are discussed.
3.1 Modular concept – extension to ZENNIUM series potentiostat
3.1.1 EL1002 electronic load
Dynamic measurements (e.g. impedance spectroscopy) on electrochemical objects
is a topic of high interest in the field of electrochemistry. Modern EIS instruments
cover a broad frequency range from µHz to MHz and can handle impedances ranging
from µΩ to GΩ. However, the maximum applied current is mostly limited to a few
amperes. For many applications in the field of batteries and fuel cells, measurements
at high currents are desired. For the ZENNIUM series potentiostats, the current
range can be significantly extended using Zahner’s electronic load EL1002.
The EL1002 is a single quadrant potentiostat (it can sink but cannot source current)
and is designed to be used as an extension of the ZENNIUM potentiostat to
investigate high power electrochemical systems. The highly dynamic EL1002 load is
optimized for galvanostatic EIS measurements up to 100 kHz on energy storage and
conversion devices such as proton-exchange membrane (PEM) and solid oxide (SO)
fuel cells.
The EL1002 allows for power dissipation of up to 1 kW in terms of voltages up to
100 V and currents up to 200 A. In combination with a third-party instrument
(electronic loads or sources), measurements at higher currents (up to 680 A) can be
carried out. Moreover, the EL1002 setup can be combined in different ways with
power supplies to allow for measurements on electrolyzers and large format
batteries.
Equipping our ZENNIUM potentiostat with our parallel measurement channel cards
(PAD4), the EL1002 and an optional power supply upgrades the whole system as an
optimal system for all kinds of stack measurements on batteries, fuel cells and
electrolyzers. For the connection of the EL1002 with the ZENNIUM potentiostat, an
EPC42 interface card is also used.

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3.1.2 EPC42 controller card
An EPC42 card has 4 connection ports by which up to 4 external devices (PP2X2,
XPOT2, EL1002) can be connected. Up to four EPC42 cards can be installed in a
ZENNIUM series potentiostat. Therefore, a total of up to 16 external devices (PP2X2,
XPOT2, EL1002) can be connected to a ZENNIUM series potentiostat with four
EPC42 cards.
Each port of the EPC42 card provides analogue and digital interfaces for the
communication between the electronic load and the ZENNIUM potentiostat. The
analogue part of the port feeds the electronic load with a signal which dictates DC
voltage as well as AC amplitude at a resolution of 16 bit. The current and voltage
signals measured by the electronic load are forwarded via the digital part of the port
to the ZENNIUM, where they are processed in the same way as the signals from the
internal cards. This means the signals are quantized with up to 24 bits. The EPC42
card provides a bandwidth of 250 kHz.
A bi-directional serial communication line allows to digitally control the external
potentiostat functions and measuring ranges.
Multiple external power potentiostats or loads can be simultaneously connected to
a ZENNIUM series potentiostat but can only be operated sequentially.
Simultaneously controlling multiple external device in the modular mode is not
possible.
Never plug or unplug the D-SUB connector at the backside of the EL1002 while the
ZENNIUM is switched on. Otherwise, the devices and the object may be damaged.
It is recommended to fasten the D-SUB connector with the screws to prevent
accidental unplugging.

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3.2 Stand-alone mode
Zahner’s power potentiostats or electronic loads (PP2X2, XPOT2, EL1002) can also
be operated in stand-alone mode, for which a Windows 10/11 or Linux computer is
necessary. For software updates, Windows 10/11 is required and the use of a virtual
machine is not permitted. The application of a USB hub for connecting the device is
not recommended.
The PP2X2/XPOT2/EL1002 potentiostat can also be controlled with other third-party
software (e.g., Python). This allows for the integration in already established
experimental setups. The potentiostats provide serial interfaces via the USB serial
port which can be used to communicate with the potentiostat via the SCPI protocol.
In the future, it is planned that the ethernet interface will be activated via a free
software update.
Zahner has prepared a GitHub library for controlling the PP2X2/XPOT2/EL1002
potentiostats with Python via SCPI:
https://github.com/Zahner-elektrik/zahner_potentiostat
And a GitHub repository with examples using the library:
https://github.com/Zahner-elektrik/Zahner-Remote-Python
The API documentation can be found at:
https://doc.zahner.de/zahner_potentiostat
Only DC measurements can be carried out in the stand-alone mode.

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4Operation basics
The EL1002 electronic load is a one quadrant potentiostat. This means that it can
sink (but cannot source) current in a fixed, given polarity. Hence, when the EL1002
is connected to a battery, it can only discharge the battery, while charging is not
possible without a third-party source.
Typical applications of the EL1002 are discharging experiments at (rechargeable)
batteries and fuel cells. The EL1002 can be operated in both potentiostatic and
galvanostatic modes, controlled by the software. For low impedance objects such
as batteries and fuel cells, the galvanostatic mode is highly recommended. The
EL1002 is optimized for galvanostatic impedance measurements.
4.1 Signals & connections
Fig. 1: EL1002 front panel
Fig. 2: EL1002 back panel

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4.1.1 Conductor rails
The EL1002 copper rails feature M10 screw threads for proper mounting of the
cables. The screws should be tightened with a maximum torque of 47 Nm,
corresponding to the torque of screws with a strength class of 8.8. The screws must
be driven through the entire copper rail (15 mm thread depth in the copper). It is
recommended to use screws with a strength class of 8.8 and a length exceeding
15 mm, depending on the thickness of the cable lug.
EL1002 has three terminals at the backside of the device labeled as positive (+),
negative (–) and external positive (EXT+) terminals. The EL1002 only allows current
(I) flow into one direction from the +to the –terminal. This means that a device
under test (DUT) e.g., a battery may only be connected to the EL1002 in one polarity.
Always connect the negative (–) pole i.e., anode of a battery with the – terminal
of the EL1002 and the positive (+) pole i.e., cathode of a battery with the + terminal.
If the DUT is connected to the EL1002 using wrong polarity, the polarity error LED
will light up. However, when the EL1002 is combined with an external power supply
via the EXT+ terminal (see chapter 6), then the current (i) may flow into both
directions between the EXT+ and – terminals.
Fig. 3: EL1002 connection scheme
For simplification, we will distinguish the current between the +and –terminals of
EL1002 with Iand current between EXT+ and –terminals of EL1002 with i.
i
I

Electronic Load – EL1002 -12-
The current Iis limited to +200 A (unidirectional, single quadrant, sink).
The current iis limited to ±680 A (bidirectional).
4.1.2 Safety interlock
The output stage of the EL1002 can be switched off by a potential-free relay contact
by opening the interlock contact. The cable should be as short as possible and
twisted to avoid interferences. The connection from the copper rails EXT+ to - is not
interrupted when the interlock is opened.
The EL1002 and the software do not recognize whether the interlock is open or
closed.
The interlock only interrupts the gate voltage (control voltage) of the power
transistors of the current controller. No relay or anything comparable is opened. If
the power transistors are faulty and short-circuited, they cannot be interrupted.
Carefully read the risk assessment document for the operation of the EL1002.
4.1.3 Signal LEDs & buzzer
The EL1002 is equipped with various signal and warning LEDs on the front panel as
well as a buzzer.
The status LED lights up green when the CPU of the EL1002 is running and the
device is ready for use. When the CPU is busy with a task or command, the status
LED lights up orange. The active LED lights up green when the power supply of the
device is switched on. When the output stage (current controller) of the EL1002 is
switched on, the LED lights up orange.
The polarity error indicating wrong connection between EL1002 and an active object
is only shown by a LED as warning signal. All other errors such as over-current or
over-voltage, power or temperature limits are displayed by LEDs’ lighting up above
certain threshold values and additional buzzers beeping above a second set of
threshold values.
The warning threshold at which the LEDs start to light up is set at about 95% of the
maximum allowed limits, whereas the buzzer sets in when the limit is exceeded.

Electronic Load – EL1002 -13-
4.2 Operation steps
1. Turn ON external power supply/load (if it is planned to be used).
2. Turn ON the ZENNIUM device as well as the EL1002 and allow for 30 minutes
of warm-up time.
3. Start the Thales software.
4. Select the EL1002 device in the Test Sampling Window. This will initiate a
calibration procedure of EL1002. At this time, no current should flow between
EXT+ and - terminals under any circumstances.
5. Select the desired potential range and reference electrode.
6. Connect the sense cables to the DUT with correct polarity – connect the blue
sense cable to the negative terminal and the green sense cable to the positive
terminal of the DUT.
7. The displayed potentials in the Test Sampling Window must be negative.
8. The potential difference between the positive and negative terminal of EL1002
must not exceed the selected voltage range of 4 V or 100 V, respectively
(absolute limit: 100 V)
9. Connect the power cables to the DUT (as well as to an external power supply
or load/sink, if necessary) according to the preferred configuration.
10. Connect the PAD4 sensing cables (if required) and activate the data
acquisition from PAD4 cards in the Thales software.
11. Select the potentiostatic or galvanostatic mode and turn ON (for low Ohmic
DUT the galvanostatic mode is recommended).
12. Perform the experiment.
13. Turn OFF the potentiostat/galvanostat.
14. Shut down the Thales software.
15. Turn OFF the EL1002 and ZENNIUM.
16. Turn OFF the external power supply/load.
17. Remove all the cables (sense and power cables).
If the external power supply is required to supply the DUT, skip the last two steps.

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⚠�Do not sink external DC current during EL1002 start up and calibration. No current
is allowed to flow through the current measuring device, otherwise it will be calibrated
as an offset.

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5Thales software
The EL1002 requires Thales version 5.8.3 or later.
All external potentiostats or the EL1002 are directly controlled by the Thales
software. In Thales, each device has a unique device number which is identical to
the EPC42 port number to which the external potentiostat or EL1002 is connected,
if no RMUX card is installed. For example, if a device is connected to EPC port 3,
then in Thales the device is addressed as “device number 3”. Device number 0 is
reserved for the internal main potentiostat of the ZENNIUM series potentiostat.
If a RMUX4 or RMUX16 (relay multiplexer) card is installed in a ZENNIUM series
potentiostat, then the first 4 or 16 device numbers (per RMUX card) are assigned to
the RMUX channels, respectively. Hence, if one RMUX16 card is installed, the device
numbers 1-16 are assigned to the RMUX16 channels. Similarly, if 2 RMUX16 cards are
installed, the device numbers 1-32 are assigned to the RMUX16 channels.
To select a potentiostat in the Thales software, follow these steps:
1. Start the Thales software in the classic mode.
2. Click on the “EIS” icon.
3. Click on “Control potentiostat”.
4. Click on the “DEVICE” button in “Test sampling & control potentiostat” window.
By clicking on the “DEVICE” button, an input box opens where the user can type in
the device number. After confirming, the device is selected and the type of device
is displayed.
Fig. 4: Selecting an external potentiostat in the test sampling window. DEVICE 1: EL1002 indicates
that the EL1002 is connected to the port 1 of the EPC42 card.

Electronic Load – EL1002 -16-
If no device is connected to the selected EPC42 port, an error message is displayed
and the Thales software automatically switches to the internal potentiostat.
If the selected device is connected, the Thales software automatically starts the
start-up calibration routine of the external potentiostats upon selection.
Thales outputs an error message if no calibration data is found for the device and a
question mark (?) is displayed after the calibration button on the GUI.
Fig. 5: Test sampling page
Connect the blue sense cable to the negative (–) terminal and the green sense cable
to the positive (+) terminal of the DUT. This will lead to correct polarity display and
a negative potential in the DC VOLTAGE window.
When the mouse cursor hovers above a button or input box and the item is
highlighted, the current and voltage displays are not updated.
In “check cell connections” one can set the desired potential range (4 V / 100 V) and
may choose a reference electrode. For convenience, the EL1000 connection scheme
with the third-party DC load is shown in Fig. 6 (same for EL1002).

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Fig. 6: Check Cell Connections page
After choosing the desired voltage range and the reference electrode settings, one
may connect the sense cables from the EL1002 to the DUT. Thereafter, connect the
power cables used for the desired EL1002 arrangement, making sure the correct
polarity. Please note that by connecting the power cables, the potential must not
change considerably (connect power cables as shown for your preferred
arrangement in the manual below). If the voltage changes when the DUT is
connected to a switched-off EL1002, there is probably a fault in the circuit.
When the DUT is connected correctly, the voltage is negative and the current flowing
into the EL1002 is positive.
When changing the device number, the now unselected external potentiostat or
EL1002 will hold its DC conditions such as DC potential or current and its on/off
status until the settings are changed again.
Voltage and current outputs of the unselected external potentiostat are not
measured and are not monitored for defined voltage/current limits.
Only the selected external potentiostat is internally connected to the FRA of the
ZENNIUM series potentiostat. Therefore, only the active external potentiostat can
output an AC signal for EIS.

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6Cell connection fundamentals
All Zahner’s potentiostats follow the same 4-electrode cell connection scheme,
which is also referred to as 4-terminal sensing or Kelvin connection. This includes
connections to the working electrode (copper rail denoted with –), counter electrode
(copper rail denoted with +), working electrode sense (WES), and reference
electrode (RE). These connections are specified by their color code, with WES: blue
and RE: green, while the copper rails are labelled on the rear panel. To minimize
interference due to stray- and mutual inductance, the power cables (current-
carrying cables) should be twisted around each other to the longest-possible length,
and moreover, the green and blue sense cables should also be twisted. For
simplification, twisting is not depicted in the schematic below.
Fig. 7: 4-electrode connection scheme. The current is conducted through the black (WE) and red
(CE) wires. The voltage is measured between the green (RE) and blue (WES) wires.
For high current flow, the 4-electrode connection scheme is highly recommended to
minimize the error margin in the measurement, especially when using the EL1002.
6.1 Contact resistance
Fig. 8 shows a typical electrical wire connection between the potentiostat and the
test object. The resistance of the wire can be divided into two parts, being the wire
resistance and the contact resistance.
Fig. 8: Typical electrical wire used to contact potentiostat with a test object. Resistance of the
electrical wire is divided into two different parts. 1) contact resistance Zcontact and
2) wire resistance Zwire.

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6.2 Four-electrode cell connection scheme
The advantage of a 4-electrode connection scheme is illustrated in Fig. 9. A pouch
cell is connected to the ZENNIUM potentiostat using a 4-electrode connection
scheme. With the WES and RE being directly connected to the pouch-cell, the
contact resistance for the WE and CE can be ignored as they don’t affect the voltage
drop between WES and RE, which cannot be realized in a 2-electrode connection.
a)
b)
Fig. 9: (a) 4-electrode connection scheme for a 2-electrode pouch cell. For optimum measurement
results, the WE and CE as well as the RE and WES cables must be twisted around each other as
separate pairs (not displayed in the image). (b) Electrical equivalent circuit of the cell connection
displayed in (a).
In this chapter, images from the ZENNIUM potentiostat are used for the sake of
simplicity and to explain the two and four electrode connection scheme. When
working with EL1002, the BNC connectors of the ZENNIUM potentiostat shall be left
unconnected and should not be connected to the test object.
The voltage across the pouch-cell can be calculated using the following equation.
The intrinsic cell voltage is neglected in this consideration.