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Technical Information
Single Cell Voltage Measurement Device
Measuring instrument for recording of individual cell voltages.
LENA-PRO 3.X is a high-quality, inexpensive device for recording and monitoring of the tensions on each individual fuel cell stack of a fuel.
• base unit with 32 analog input ports
• base unit internal cascadable for 32/64/96/128 analog input ports
• intelligent signal processing through microprocessor technology
• galvanic isolated RS232 communication port
• average determination utilizing eight measured values
• determination of the three lowest voltage values linked to respective
measuring points
• determination of total voltage based on all single cell voltage values
• measuring of total voltage for direct comparison
• direct voltage supply from fuel cell possible
• shielded enclosure 145 x 87 x 37 mm³
leno pro 3.x


Supply voltage:
5 ... 26 VDC
Power input:
30 ... 120 mA
Operating temperature:
-5 ... +40 °C
Measurement voltage:
0 ... 1 V
Measurement resolution:
10 bit
Measurement accuracy:
± 3 mV
Sampling rate (64 cells):
1 Hz
Communication speed:
19.200 Baud

Operating Conditions :

Ambient temperature:
-10 ... 50 °C
Operating temperature:
-5 ... 45 °C
Ambient humidity
(non condensing):
0 ... 90 %

Connection form LENA-PRO 3.X system to fuel cell stack:

Connection of single cells to the LENA PRO 3.X system is achieved by 37 pole SUB-D connectors. Depending from configuration the unit is equipped with 1 up to 4 SUB-D connectors.


lena pro 3-32


lena pro 3.64


maximum 32 cells maximum 2 x 32 cells
w: 45 mm
h: 105 mm
d: 154 mm
w: 45 mm
h: 105 mm
d: 154 mm
Figure 1 Dimensions and wiring diagramm up to 64 cells
Notice: The second SUB-D connector is rotated by 180 ° in opposite to the first one.
LENA PRO 3.128

leno pro 3.96


lena pro 3.128


maximum 3 x 32 cells maximum 4 x 32 cells
w: 80 mm
h: 105 mm
d: 154 mm
w: 95 mm
h: 105 mm
d: 154 mm
Figure 2 Dimensions up to 124 cells

To achieve the best measuring results we strongly recommended to connect all unused analog inputs from LENA-PRO 3.X with the last used input pin.

lena pro funktioneller aufbau
Figure 3 functional system design of LENA-PRO 3.X

Connection form LENA-PRO 3.X System to PC or PLC/controller:
The connection to SPS or controller system is achieved via an RS232 interface.

Communication Connection:

SUB-D 9 pole connector power supply / RS232
Power ground PIN 1
Power Supply 12 to 26 V PIN 4
RS232 ground PIN 5
Limit value connector cell 1 - 32
(dry contact)
PIN 6 + PIN 7
Limit value connector cell 33 - 64
(dry contact)
PIN 8 + PIN 9
Notice: Limit value detection consists of dry contacts with a maximum load rating of 0,5 A and 30 VDC. They are assigned a fixed limit value of 400 mV. If measured value falls below the limit, the dry contact is going to open. During normal operation, contacts are closed. Upon reaching limit value, contacts will open for at least 1 second. For connection to standardized RS232 interface of a PC a null modem connector cable must be used!

Specification of RS232 interface:

Data bits: 8
Stop bits: 1
Parity: non
Baud rate: 19200 Baud/s

Description of interface software:

The unit works fully autonomous and aquires the measurement values with maximum speed. Measured values are stored inside the unit.
Sending the ASCI character [S] (call for data) causes the transmission of the measured values via RS232 interface from the unit to the controller or PC. They are formatted as follows (all ASCI characters):

  [s] (start of data sequence)  
  value of cell 1  
  value of next cell  
  up to value of last cell  
  lowest value 1  
  cell number of lowest value 1  
  up to lowest value 3  
  cell number of lowest value 3  
  total voltage value  
  CR/LF (end of data sequence)  
The measurement unit of the transmitted values is mV. Separation of values by semicolon [;], start of sequence [s], end of sequence [CR/LF]. The cell to be measured is assigned by transmitting [Z+numeric digit(s)+CR/LF]. Command confirmed output of [z;>Number<].


LENA-PRO system will put out following string after initialisation on power-up:
[LENA M8.64.2] [CR/LF] [z;64] [CR/LF]

M8.64.2 denominates software version of unit, [z;64] denominates number of cells where 64 will take the value of cells actually measured.

This string will also be put out upon changing cell number in order to confirm change command. A RESET will be initialised through the integrated watchdog-timer. The timer has been set at a default value of 1 second and is reset interally after each cycle.

In the event that instead of [S] (call for data) or [Z] (change of cell number) a different character is transmitted, it will provoke the watchdog-timer to immediately proceed with a RESET. The change of number must be transmitted in the sequence shown above within one second. Otherwise the watchdog-timer will proceed with a RESET.


Please follow the installation instructions on CD.

When data logging is activated, the measured data will be stored in a file sorted into the following columns:

... CellXX

Measured values are in mV.

The LENA-PRO 3.X devices are designed on the basis of the current state of technology and approved safety-related regulations. However the incorrect or not intended utilisation may cause danger for life or physical condition of the user or third party or rather damnification of the devices and other real values. The devices are meant to be a single cell voltage measuremtent system for PEM-fuel cells. Another or any other utilisations beyond this are not in accordance to the use of the LENA-PRO 3.X system. The manufacturer/supplier takes on liability for resulting damages. The risk is taken by the user.

Item and Price:

Price in Euro
on request
on request
on request
LENA PRO 3.128
on request

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Fuel Cell Technology
Danziger Straße 8
DE-73035 Goeppingen

phone +49 (0)71 61 / 94 63 18
fax +49 (0)71 61 / 94 63 19
e-mail: quintech@quintech.de