ZAHNER EL300 User manual

Electronic
Loads
Installation & Operation
Manual
EL300
EL1000
03/2020

Electronic Loads -1-
Table of Contents
Unpacking.............................................................................................................................3
Basic .....................................................................................................................................4
EPC42 ................................................................................................................................4
Selecting an external device ...............................................................................................4
Changing devices ...............................................................................................................6
Potential in electronic loads EL ...........................................................................................6
Safe operation conditions (SOC).........................................................................................7
EL300 ....................................................................................................................................8
Cell connections .................................................................................................................8
1. Full cell configuration ....................................................................................................8
2.a. Half-cell configuration - Cathode ..................................................................................9
2.b. Half-cell configuration -Anode ......................................................................................9
3. Partial cell configuration ................................................................................................10
4. Application with an additional power supply ..................................................................10
Built-in buffer amplifier......................................................................................................10
EL1000 ................................................................................................................................11
Measuring floating objects ................................................................................................11
EL1000 connection ...........................................................................................................11
Cell connections ...............................................................................................................11
EL1000 operation steps ....................................................................................................12
1. Full cell configuration ..................................................................................................13
a. Current setting in EL1000 ................................................................................13
2.a. Half-cell configuration - Cathode ................................................................................14
2.b. Half-cell configuration - Anode ...................................................................................14
3. Partial cell configuration ............................................................................................15
a. PAD4 connections ...........................................................................................15
4. Application with an additional DC sink/load ...............................................................16
4.a. DUT connected with DC load and EL1000 .................................................................16
4.b. DUT connected with DC load and EL1000 (in parallel)...............................................17
5. Applications with an additional power supply .............................................................18
5.a. Charging batteries......................................................................................................18
5.b. Electrolysis of fuel cells ..............................................................................................19
5.c. Compensation of voltage drop (Zero Volt Option).......................................................20
6. Applications with an additional power supply (external input) ......................................21
Built-in buffer amplifier......................................................................................................23
Grounding circuit ..............................................................................................................23
Specifications....................................................................................................................24

Electronic Loads -2-
CAUTION
Prevent the input panel of the device from electrostatic
discharge! This may damage the device.
Do not connect active objects such as batteries or fuel cells to
the power outputs of the device when the device is off!
This may damage the device.

Electronic Loads -3-
Unpacking
Zahner products are carefully produced, calibrated and tested to achieve a high quality standard. Also
the assembling of the accessories and packing is done with great care. Please check the shipment
directly after receipt to ensure that the device and all accessories are undamaged.
The shipment must contain the following parts:
EL1000
•EL1000
•cable for connection of the EPC42 (D-Sub9 - Lemosa)
•twisted sense cable (Lemosa plug, blue & green cables)
•power cord
•this manual
EL300
•EL300 with installed control cable for connection of the EPC42 (Lemosa plug)
•2 thick cables (blue and red) with high current banana plugs (∅12mm)
•twisted sense cable (Lemosa plug, blue & black cables)
•power cord
•this manual

Electronic Loads -4-
Basics
Today, dynamic measurements on electrochemical objects are of great interest. Modern instruments
for impedance measurements, cyclic voltammograms and pulse response experiments provide a
broad frequency range from µHz to MHz. At the same time, they provide a huge impedance range
from µΩto GΩ. However, for most instruments there is one restriction left, they have a limited current
range of few Amperes. In the field of electrochemical power generation, for example, this is only
sufficient for “small” systems.
The electrochemical workstations of the Zennium family provide a current range of ±4 A (Zennium X)
and ±3 A (Zennium Pro) and measure impedances down to µΩ. Therefore, we provide external
devices (EL, PP-Series and XPOT) which can extend the application field of the Zennium systems.
The electronic loads EL300 and EL1000 are designed as additional potentiostats to allow dynamic
investigations on technical systems up to 100 A (EL300) and 200 A (EL1000). Their main applications
are discharging tests on (rechargeable) batteries and fuel cells.
The electronic loads are easily integrated in the Zennium system using EPC42 controller cards. All
functions are controlled directly from the Thales software. Up to 16 electronic loads may be controlled
by one Zennium system using up to 4 EPC42 cards.
EPC42
The EPC42 is able to control up to 4 external devices like the EL300/EL1000, the XPOT,and the
PP201/211/241. Up to four EPC42 cards can be used for installing a total of 16 external devices in a
Zennium system.
Each port provides analogue and digital interfaces for the communication of the external devices with
the Zenniumsystem. The analogue part of the port feeds the device with the DC potential at a
resolution of 16 bit and the AC amplitude. Measured current and potential are sent from the external
device to the Zennium to be treated there in a same way as signals from the internal Zennium cards.
The EPC42 has a bandwidth of 250 kHz.
A bi-directional serial communication line allows to digitally control the functions and measuring
ranges of external devices.
!
Plug or unplug external devices only when both, Zennium AND the external devices,
are switched off. Otherwise the devices may get damaged.
Selecting an external device
All external Zennium devices are directly controlled by the Thales software. Each device has a unique
device number which is identical with the EPC42 port number. So, if a device is connected to EPC
port 3, you address it with the device number 3. Device number “0” is reserved for the internal
potentiostats of the Zennium system.
If an RMUX (relay multiplexer) card is installed, the device numbers of the external devices
(ELs/PPs/XPOTs) start with 17, not with 1, because then the device numbers 1 to 16 are reserved for
the 16 RMUX channels.

Electronic Loads -5-
To select a device, call the Test Sampling page by
clicking on the “control potentiostat” option.
Click on “Device” on the left side of Hippo. This will
open an input box. Insert the EPC port number in
which the external device is connected. Here
EL1000 is connected with port 1 of EPC42.
In addition the external device can be calibrated by
clicking on the “calibration?” icon
If no device has been connected to the addressed
EPC42 port, an error message is displayed and the
software automatically selects the internal
potentiostat.
If the selected device is present but has not been activated then the software starts to calibrate it
automatically.
If an external device is changed then the new device has to be calibrated before use. The calibration
is carried out only for the selected device. All other calibration data remains unchanged.
If a device number other than 0 is selected, the parameters of the Test Sampling page now are valid
for the designated device.
The following methods are available for external devices:
EIS
impedance measurement
C/E
Parameter based impedance measurement
I/E
current potential curve recording
MIE
Multiple parallel current potential curve recording
AS
series measurements
To change the potential range of the electronic load (here EL1000), click on “check cell connections”
icon.

Electronic Loads -6-
In check cell connections, you can set the desired
potential range and choose a reference electrode.
Here for convenience, the EL1000 connection
scheme with the 3rd party DC load is also shown.
At the bottom of the page “Parallel Impedance
Setup” is provided to setup the PAD4 connections.
Once all the desired settings are complete then click
“Esc” or click on to go back to the last window.
Now connect the sense cables from EL1000 to the
device under test (DUT). Here a battery is used as a
DUT.
Connect blue sense cable to the – terminal and
green sense cable to the + terminal of the DUT. This
will show the correct polarity and a negative potential
will be shown in the DC VOLTAGE window.
Now connect the power cables for the desired EL1000
arrangement. Please note that with the connection of
the power cables the potential should not change
considerably (connect power cables as shown for
your preferred arrangement in the manual below).
If parallel impedance spectra are to be measured then
click on the “Parallel Impedance Setup” in “Check
Cell Connections”. This will open a new window
where different channels from the PAD4 cards can be
chosen. Here first 3 channels are selected which are
analysing the individual cell of the DUT (battery).
Also click on “Enable Impedance” to allow the
impedance measurement from the PAD4 channels. At
bottom right, the voltage and current from the sense
cables of EL1000 can also be seen.
Changing devices
When changing the device number, the now inactive device will hold its DC conditions such as DC
potential and on/off status as long as it is selected anew or the system is shut off. On the other hand
only the selected device is internally connected to the FRA. Therefore only this device is able to output
an AC signal superimposed to the DC potential.
Potential in electronic loads (EL)
Chemical reactions in the batteries and fuel cells provide us with energy. In the field of
electrochemistry such reactions are shown on a negative potential (energy) scale. However potentials
in the field of electronics and electrical engineering are shown with a positive sign. Hence to facilitate
the chemists in comparing the reactions and carrying out different experiments, the potential’s reading
in electronic loads (EL) is reversed. e.g., if one measure a potential of a battery by a voltmeter and it
reads +2 V then the EL300/EL1000 will read it as -2 V.

Electronic Loads -7-
Safe operation conditions (SOC)
1. Pay attention to the wire connections and strictly follow the guidelines of this manual. A
reverse polarity may damage your device (especially EL300)
2. During operation, potential on + terminal of EL1000 should be at least 1 V higher than the –
terminal of EL1000
3. Always turn ON the electronic load (EL) after turning on the external load or external power
supply
4. Always turn OFF the electronic load (EL) before turning off the external load or external power
supply
5. Properly connect (with screws) the EPC42 cable with the electronic load. An accidental
unplugging of the EPC42 cable during operation may damage your device
6. Remove all metallic jewellery/watches when working with high currents
7. Don’t touch the electrical connections during the operation
8. Never apply potential higher than the 12 V for EL300 and 100 V for EL1000.
9. The maximum current through the + terminal of EL1000 must never exceed 200 A
10.The maximum current through the shunt resistance of EL1000 must never exceed 680 A

Electronic Loads -8-
EL300
The EL300 external electronic load is a One-Quadrant-Potentiostat. This means that EL300 is only
able to sink current but cannot source current. Typical applications are discharging experiments at
(rechargeable) batteries and fuel cells. The EL-series potentiostats can be operated in both
potentiostatic and galvanostatic modes, controlled by the Thales software. For low ohmic objects,
galvanostatic mode is recommended. The output panel as well as the input panel are electrically
isolated from ground.
The EL300 is air cooled for operation till 25 A and needs water cooling when loaded with more than 25
A. For water cooling you find an inlet and an outlet at the backside of the EL300.
!
The EL300 may get damaged if more than 25 A are applied without water cooling!!!
Cell Connections
It is important to know that EL potentiostats SINK current from the device under test (DUT) and
therefore the cell connections must be as short and as thick as possible. Otherwise the
measurements may be faulty and it may even seem that the EL is defective. For this reason, the
standard cable set shipped with the ELs should be shortened as much as possible.
It is also important to connect the DUT with the correct polarity to the EL potentiostat. Whereas typical
one-cell-voltages of 0.8 V or 1.2 V do not damage an EL when being connected with the wrong
polarity, cell stacks can do very well. Therefore, we recommend connecting the sense inputs as
described in section. 1 (Full Cell Configuration). Call the Test Sampling page of the Thales software
and check for the potential polarity by connecting sense cables. It must be negative. Now connect the
power cables according to section. 1 with the potentiostatic/galvanostatic mode switched OFF. The
displayed potential must not change significantly when connecting the power cables.
With the correct polarity the DUT may be connected to the EL potentiostat in one of the following
ways:
1. Full cell configuration (Standard Kelvin Scheme)
This configuration is used with DUT like (rechargeable) batteries
and fuel cells if a complete cell is to be investigated.
!
Potential ≤4 V / 12 V
The potential will be indicated as negative in EL.
The measured current must be positive I ≥0
Always ensure the correct polarity by connecting the sense cables.
Afterwards properly connect the power cables.
The potential will be shown as negative in the Thales software.
ZAHNER
e le k trik
power
EL101
sense
lin e
a c tiv e
anode
pole
pole
cathode

Electronic Loads -9-
2.a. Half-cell configuration – Cathode
This configuration is used with DUTs like (rechargeable) batteries
and fuel cells if only the cathodic part of the cell has to be
investigated.
!
Potential ≤4 V / 12 V
The potential will be indicated as negative in EL.
The measured current must be positive I ≥0
Depending on the type of the reference electrode the measured
potential may be different from the real potential at the reference
electrode site. The real potential can be calculated from the meas-
ured potential by subtracting the potential of the reference elec-
trode.
2.b. Half-cell configuration -Anode
This configuration is used with DUTs like (rechargeable) batteries
and fuel cells if only the anodic part of the cell has to be
investigated.
!
Potential ≤4 V / 12 V
The potential will be indicated as negative in EL.
The measured current must be positive I ≥0
Depending on the type of the reference electrode the measured
potential may be different from the real potential at the reference
electrode site. The real potential can be calculated from the meas-
ured potential by subtracting the potential of the reference elec-
trode.
ZAHNER e le k trik
power
EL101
sense
lin e
a c tiv e
anode
pole
pole
cathode
ZAHNER e le k trik
power
EL101
sense
lin e
a c tiv e
anode
pole
pole
cathode

Electronic Loads -10-
3. Partial cell configuration
This configuration may be used, if a certain part of a battery or fuel
cell stack has to be investigated.
!
Potential ≤4 V / 12 V
The potential will be indicated as negative in EL.
The measured current must be positive I ≥0
Depending on the type of the reference electrode the measured
potential may be different from the real potential at the reference
electrode site. The real potential can be calculated from the meas-
ured potential by subtracting the potential of the reference elec-
trode.
4. Applications with an additional power supply
This configuration may be used if the voltage
drop on the power lines is too high to reach
the high-current test conditions. In addition it
allows experiments on passive objects and
batteries under charging conditions and elec-
trolysis cell
Built-in buffer amplifier
The built-in buffer amplifier may be used to increase the potential range of the EL up to +/-12 V. To
select the buffer amplifier select the corresponding voltage range (±4V / ±12V) at the check cell
connection page.
!
Potential ≤4 V / 12 V
The potential will be indicated as negative in EL.
The measured current must be positive I ≥0
0
20
40
60
80
Amper e
0
20
40
60
80
Volt
current l imit finecoarse
potenti al
output
Z
ZAHNER elekt ri k
power
EL300
sense
line
active
ZAHNER e le k trik
power
EL101
sense
lin e
a c tiv e
anode
cathode

Electronic Loads -11-
EL1000
The EL1000 external electronic load is a One-Quadrant-Potentiostat. This means that it is able to sink
current (but cannot source current) in a given polarity. Hence when EL1000 is connected with a
battery then it can only discharge the battery and charging is not possible without a 3rd party source.
Typical applications of EL1000 are discharging experiments at (rechargeable) batteries and fuel cells.
The EL-series potentiostats can be operated in both potentiostatic and galvanostatic modes,
controlled by the Thales software. For low ohmic objects like batteries and fuel cells the galvanostatic
mode is strongly recommended.
Measuring floating objects
On the rear of the EL1000 you will find two connectors with a jumper.
Silver banana jack (earth ground) ⇔black banana jack (system ground)
If the device under test (DUT) is floating (no metallic or electrolytic contact to ground) it is necessary to
set the jumper. Then the EL1000 signal ground (- Terminal of EL1000) is connected to earth ground
via a 100 Ωprotective resistor.
If any part of the cell is grounded, the jumper must be removed. Then the EL1000 power stage is only
AC coupled to earth ground.
!
When investigating floating objects the jumper must be set and vice versa.
EL1000 connection
EL1000 must only be connected or disconnected to the Zennium system if both, the Zennium and the
EL1000 are switched off.
If you want to use the EL1000 as a stand-alone device, unselect it in the Test Sampling page of the
Thales software (you may e.g. change the device number to the main potentiostat). The inactive
device will hold its DC conditions such as DC potential and on/off status as long as it is selected anew
or the system is shut off. Now you may unplug the EL1000 at the EPC42 connector. For regaining
access to the EL1000, connect it to the EPC42 and select it in the Test Sampling page of the Thales
software.
Note: AC potential is modulated by the FRA in the Zennium device; hence a stand-alone EL1000 can
only provide the DC potential (without internal connection to FRA). For AC signalling, it is necessary
that the EL1000 is in contact with the Zennium device.
Cell connections
It is important to know that EL potentiostats SINK current from the DUT and therefore the cell
connections must be as short and as thick as possible. Otherwise the measurements may be faulty
and it may even seem that the EL is defective.
It is also important to connect the DUT to the EL potentiostat with the correct polarity. When being
connected with the wrong polarity, the EL1000 has a protection circuit and will indicate polarity error.
Therefore, we recommend connecting the sense cables as described in EL1000 operation steps. Call
the Test Sampling page of the Thales software and check for the potential polarity. It must be
negative. Now connect the power cables according to scheme provided below with the
potentiostatic/galvanostatic mode switched OFF. The displayed potential must not change significantly
when connecting the power lines.

Electronic Loads -12-
EL1000 operation steps
11. Check if the device under test (DUT) is grounded or not. Then adjust the grounding of
EL1000 accordingly.
12. Turn ON external power supply/load (if any is required)
13. Turn ON Zennium device and EL1000 (allow for 15 minutes warm up time)
14. Start Thales software
15. Select the EL1000 device in the Test Sampling Window. This will start a calibration of
EL1000
16. Select desired potential range and reference electrode
17. Connect the sense cables to the DUT with correct polarity -connect blue sense cable at
negative terminal and green sense cable at positive terminal of the DUT -
18. Potentials in test sampling window must be negative
19. Potential difference between the positive and negative terminal of EL1000 must not exceed
100 V (in any input voltage range: 4V/100V)
20. Connect power cables to DUT (to external power supply or load/sink) -according to the
preferred configuration-
21. Connect PAD4 cables (if required) and choose PAD4 option from the Thales software.
22. Choose potentiostat/galvanostat mode and turn ON (for low ohmic DUT, galvanostatic mode
is recommended)
23. Perform the desired experiment
24. Turn OFF the potentiostat/galvanostat mode
25. Shut down the Thales software
26. Turn OFF the EL1000 and Zennium
27. Turn OFF the external power supply/load
28. Remove all the cables (sense and power cables).
NOTE: If the external power supply is required to power the DUT then skip last two steps (section 6).
With the correct polarity, the DUT may be connected to the EL1000 potentiostat in one of the different
ways described in the rest of this manual.

Electronic Loads -13-
1. Full cell configuration (Standard Kelvin Scheme)
This configuration is used with DUTs like (rechargeable) batteries and fuel cells if a complete cell has
to be investigated. Here, first the sense cables are attached to the DUT with the correct polarity and
then power cables are connected. Since EL1000 is a one quadrant potentiostat so it cannot act as
source but only work as load. Hence it is recommended to use as short and as thick as possible
cables to minimize the resistive losses during operation.
!
Potential ≤4 V / 100 V
The potential will be indicated as negative in EL
The measured current must be positive I ≥0
Graph 1: One-Quadrant representation showing battery or fuel cell
connection with the EL1000
Graph 1 shows the one quadrant representation of the EL1000 connection with the DUT (3 V battery
or fuel cell). In this graph the X-axis represents the – terminal of EL1000 and Y-axis represents the +
terminal (with the maximum potential limit of 100 V). In part a, the anode (negative electrode) of the
DUT is connected with the – terminal of EL1000 and is at system ground. While the cathode
(positive electrode) is connected to the + terminal of EL1000 (connected to Y-axis via blue line). Here
the potential is positive but it will be indicated as negative in Thales software. In this representation the
current flow is counter clockwise (current > 0). EL1000 will read the potential with sense cables
(around DUT – battery) and will always read -3 V. However between the +and – terminals of the
EL1000, the output potential will be less than 3 V. This decrease (see Graph 1b) is due to the voltage
drop (V = I*R)within the system. This voltage drop depends on the current flowing through the system.
Hence if the current is high then the voltage drop will also be high. When sinking high currents from
low cell potentials (like big single fuel cells) the input potential (at EL1000 + terminal) can become less
than 1 V. In such conditions, the EL1000 will not work properly. Hence when controlling current, keep
in mind that high currents will increase the voltage drop and pay attention to the input potential.
Current setting in EL1000
EL1000 has 3 terminals at the back side of the device labelled as positive (+), negative (-) and
external positive (EXT +) terminals. EL1000 is a one quadrant potentiostat and can only work as a
load. So it allows current (I) flow only in one direction (clockwise inside EL1000) between its +and –
terminals (see Fig. 01). This means that a DUT (e.g., battery) can only be connected with EL1000 in
one polarity. If that DUT is connected with EL1000 in wrong polarity, the polarity error LED will indicate
this. However, when EL1000 is used with an external power supply via Ext + terminal (see chapter 6)
then the current (i) can flow in both direction between the EXT + and –terminals.

Electronic Loads -14-
In EL1000, the +terminal is thinner as compared to –and EXT + terminals because the maximum
allowed current which can flow from +terminal is 200 A whereas between –and EXT + terminals, a
maximum current of 680 A can flow.
2.a. Half-cell configuration – Cathode
This configuration is used with DUTs like (rechargeable)
batteries and fuel cells if only the cathodic
part of the cell has
to be investigated.
!
Potential ≤4 V / 100 V
The potential will be indicated as negative in EL
The measured current must be positive I ≥0
Depending on the type of the reference electrode, the
measured potential may be different from the real potential at
the reference electrode site. The real potential can be
calculated from the meas
ured potential by subtracting the
potential of the reference electrode.
2.b. Half-cell configuration -Anode
This configuration is used with DUTs like (rechargeable)
batteries and fuel cells if only the anodic part of the cell is to be
investigated.
!
Potential ≤4 V / 100 V
The potential will be indicated as negative in EL
The measured current must be positive I ≥0
Depending on the type of the reference electrode, the
measured potential may be different from the
real potential at
the reference electrode site. The real potential can be
calculated from the meas
ured potential by subtracting the
potential of the reference electrode.
Fig 01: Current flow direction between +and –terminals and –and EXT + terminals of EL1000
For ease, we will distinguish the current between the +and –terminals of EL1000 with Iand current
between EXT + and –terminals of EL1000 with i.

Electronic Loads -15-
3. Partial cell configuration
This configuration may be used, if a certain part of a battery or
fuel cell stack has to be investigated.
!
Potential ≤4 V / 100 V
The potential will be indicated as negative in EL
The measured current must be positive I ≥0
Depending on the type of the reference electrode, the
measured potent
ial may be different from the real potential at
the reference electrode site. The real potential can be
calculated from the meas
ured potential by subtracting the
potential of the reference electrode.
PAD4 connection
A PAD4 card provides 4 additional channels
for impedance measurements. These channels
allow for a simultaneous investigation of
different parts of the DUT. With Zennium X, up
to 4 PAD4 cards can be installed and 17
parallel impedance measurements can be
carried out. An application of such a setup is
simultaneous investigation of 17 cells in a
battery. A schematic of such a system with 3
PAD4 channels is shown.
NOTE: The +, -and EXT + terminals are
provided at the back of EL1000 whereas the
sense cable connection is at the front of
EL1000.

Electronic Loads -16-
4. Applications with an additional DC load
4.a. DUT connected with DC sink and EL1000
This configuration may be used to sink more current through the DUT than 200A. The total amount of
current from the EL1000 and the additional electronic load must not exceed 680A!
The maximum power dissipation in EL1000 should not increase the EL1000’s limit of 1000 W.
Example:
DUT: Battery of 48 V potential at 210 ADC and measure EIS with 5 A amplitude:
EL1000 part of the DC current: 10 A
EL1000 AC amplitude: 5 A
EL1000 power dissipation: 48 V * 15 A = 720 W (<1000 W)
External load DC current: 210 A - 10 A = 200 A
EIS settings in the control potentiostat menu: Galvanostatic, DC current 210A, Amplitude 5A
Note:–Maximum allowed current through EL1000 in above example = 1000 W / 48 V = 20.8 A
Here PAD4 cards can also be used to investigate the individual cells of a battery or fuel cell. The
potential range of a PAD4 cards is fixed at ±4 V with the compliance voltage of ±100 V. Higher input
voltage ranges can be achieved by special sense cables (±5 V, ±10 V, ±12 V, ±20 V, ±24 V). However
!
Potential ≤4 V / 100 V
The potential will be indicated as negative in EL
There are two current loops and both currents flow through the EL1000 shunt
1) From EL1000 to DUT
2) EL1000 Ext + to 3rd party load to DUT
The measured current (total of both current) must be positive I
≥
0
The total current must NOT EXCEED 680 A (max. 200 A from EL1000)
Ensure to switch ON the external load before switching ON EL1000
Ensure to switch OFF EL1000 before switching OFF the external load
During EL1000 startup and calibration do not sink external DC current
EL1000 DC current has to be defined as sum of both currents -
> The EL1000 controls the
current through the DUT

Electronic Loads -17-
with increasing potential range, the resolution of the impedance spectra measured by PAD4 will
decrease.
4.b. DUT connected with DC load and EL1000 (in parallel)
To sink more current from DUT than allowed by an EL1000, an external load can also be connected in
parallel to the DUT and EL1000 as shown below. This allows for an independent control of EL1000
and external load on DUT
In Graph 2, the X-axis represents the – terminal of EL1000 and the Y-axis represents the + terminal
of EL1000. Graph 2 illustrates the two independent current loops for the parallel connection of the
Graph 2: EL1000 and an external load in parallel connection with a DUT (battery/fuel cell)

Electronic Loads -18-
EL1000 and an external load with the DUT. Here the current flowing through the external load (I2)
does not flow through EL1000 and can be independently controlled by the external sink and limitations
from EL1000 do not apply to I2. Since the current flowing through the external load is not flowing
through the EXT + terminal of EL1000 hence it is not labelled with ibut I2.
Resistance box (R) in Graph 2 represents the voltage drop in EL1000 current loop during operation.
5. Applications with an additional power supply (serial)
This configuration may be used if the voltage drop on the power lines is too high to reach the high-
current test conditions. In addition it allows experiments on passive objects and batteries under
charging conditions and electrolysis cell. Here EL1000 is connected in series with DUT (inversed
battery) and the external power supply.
5.a. Charging batteries
This configuration is used for experiments on batteries under charging conditions and electrolysis
cells.
Graph 3 follows the same scheme as described previously in this manual. The X-axis represents the
– terminal of EL1000 and the Y-axis represents the + terminal of EL1000. Graph 3 (Part a) is same
as shown in Graph 1(a). As explained in previous graphs that the EL1000 allows current flow in one
direction (counter clockwise) and here this current flow is represented as I+. When EL1000 as a load is
connected with a battery then it discharges the battery. For charging the battery, a reverse current (I-)
should flow through the battery which is not possible with EL1000. Hence to charge a battery during
experiment with EL1000, an external source is required as shown in Graph 3(b). This external source
applies a potential against the battery and changes the current direction in the battery, charging it. It
should be noted down here that the potential of the external source should be higher than the battery’s
!
The DC potential applied must not exceed
Umax = 100 V.
Potential
≤
4 V / 100 V
The potential will be indicated as positive in EL
(because the
battery connection is reversed
with sense cables)
The measured current must be positive I ≥0
Graph 3: EL1000 in series connection with a battery and an external source (power supply).

Electronic Loads -19-
potential. Graph 3(c) indicates the same situation as described in Graph 3(b), however here voltage
drop in the system is also taken into account. The blue line at the y-intercept shows the potential
output between the +and – terminals of EL1000. A simple schematic is Graph 3(c) is also shown
below to clearly indicate the connections of battery (reversed) with EL1000 and external source.
Note: Normally a cathode (positive terminal) of battery is connected with the + terminal of EL1000
(Graph 4a) however during charging (Graph 3b,c) the anode (negative terminal) of the battery is
connected with the + terminalof EL1000. Hence it is also described as the reverse connection of
battery with EL1000.
Fig. 02 shows the same connection as shown in Graph 3(c). Here, EL1000 will read a potential of less
than 1 V between its +and – terminals. Here the potential applied by the external power source
should be increase up to an extent that the total potential becomes positive after compensating for the
opposing battery potential and the voltage drop (R).
5.b. Electrolysis of fuel cells
This configuration is used to allow experiments during electrolysis of
fuel cells. Electrolysis of the fuel cell has the same cell connection as
for the section of 5.a. Charging batteries.
!
Potential ≤4 V / 100 V
The potential will be indicated as positive in EL.
The measured current must be positive I ≥0
The graphical representation for fuel cell will also look similar as the
Graph 4 for batteries. However since the individual fuel cell has a
potential of nearly 1.1 V so an external power supply with less
potential is normally used.
In section 5.a and 5.b, the currents can be disrupted directly from
EL1000. Since external power supply is in series with EL1000 so by
stopping the current in EL1000, the current flow by the external power
supply will also seize.
Fig. 02: EL1000 in series connection with a battery (reversed connections) and an external power source.