Samlex America BATTERY MONITOR BW-03 User Manual
Battery monitor bw-03 | owner's manual, Description, Features
 
SAMLEX AMERICA, INC.
| 1
Read OwneR's Manual caRefully BefORe installing Bw-03.
Description
The BW-03 is a smart battery monitor that can measure and display the voltage 
of one or two battery bank(s). It can also generate an alarm for overvoltage, 
undervoltage and voltage differences. 
Features
- Shallow mounting depth
- Multiple battery monitoring
- Open Drain alarm output
- Programmable alarm thresholds
- Very low power consumption
Layout
Layouts of the top and back of the unit are shown in Fig 1A & 1B, respectively.
Installation
Warnings
- The unit should be installed only by skilled installers / electricians who are
aware of regulations for working with batteries.
- Live parts must never come into contact with the housing of the BW-03.
- Use of poor quality material and/or excessively low diameter cables for 
making the connections can damage the BW-03.
- A short circuit between the Positive and Negative terminals of the battery
may cause severe damage to your system.
- Always use fuses (of the correct value) as shown in the connection
diagrams (pages 3 & 4).
Various connection configurations are shown in Figs 2 to 7. Please strictly follow the 
order of connections given below:
Monitoring 1 Battery Bank 
(Figs. 3 and 4):
1. Connect the Negative of the battery bank to the Minus Input Terminal
marked (MIN).
2. (Optional) Connect the external alarm relay / LED from the battery Positive
to the Alarm output Terminal (OUT) - See Fig 2.
3. Connect the Positive terminal of the battery to the Positive Input Terminal
marked (BAT1).
Monitoring 2 Battery Banks 
(Figs. 5, 6 and 7):
1. Connect the Negative of the 2 battery banks to the Minus Input Terminal
marked (MIN).
2. (Optional) Connect the external alarm relay / LED from the battery Positive
to the Alarm output Terminal (OUT) - See Fig 2.
3. Connect the Positive terminal the first battery bank (any one of the two
battery banks) to the Positive Input Terminal marked (BAT 2) .
NOTE: It is important the this first connection is made on Terminal
(BAT 2) and NOT on Terminal (BAT1).
4. Connect the Positive Terminal of the second battery bank to the Positive
Input Terminal marked (BAT1).
Operation
Immediately after connection, the voltage of BAT 1 is displayed to an accuracy of 
one tenth of a Volt. If use is also made of the BAT 2 terminal, then the BAT 1 point 
(1B, Fig 1A) will flash slowly (1x per 2.5 second). This is to indicate which battery 
voltage is actually being displayed. When the Programming Button is pushed briefly 
(for less than 2 seconds), the voltage of BAT 2 appears on the display. The associated 
indication point, BAT 2 (1D, Fig 1A), now flashes slowly.
Alarm
BW-03 can generate an alarm for three different situations. These are alarms for 
undervoltage, overvoltage and voltage difference (programmable values are given 
in Table 1). As soon as an alarm starts, the display will continuously switch between 
showing the alarm that has been activated (“lo”, “hi” or “diF”) and the voltage value 
of the selected voltage input. The buzzer and Alarm Out Terminal (OUT, 
Fig 1B) will also be activated.
An alarm lasts for one minute, or until the Programming Button (2, Fig 1A) has been 
pressed for two seconds. After this, the alarm state continues in silence. This means 
that the buzzer and Alarm Out Terminal (OUT, Fig 1B) have now been deactivated 
and the display – just like normal – continuously indicates the reading from the 
selected battery. One of the Battery 1 (1B, Fig. 1A) or Battery 2 (1D, Fig. 1A) points 
will now start to flash quickly (± 2x per second) to indicate there is an alarm. In the 
case of a difference alarm, both points will flash quickly. The alarm is fully reset as 
soon as the voltage reaches a normal value once again. 
Power Saving Mode
If a voltage is connected to BAT 1 that results in the activation of an undervoltage 
alarm, the display will be switched OFF 10 minutes after the starting of the alarm. 
The application will continue to work in the background and if another voltage level is 
exceeded, the alarm will activate. In this case, the display is also (temporarily) switched 
ON. The display is also switched ON if the Programming Button is pushed or if the 
voltage of the BAT 1 input rises.
As long as the voltage has not risen above the charging voltage for three days (12.8V 
for a 12V system and 25.6V for a 24V system), there has been no alarm and the user 
has also not pressed the Programming Button, then the application will reduce power 
consumption further by suspending all activities. Briefly pressing the Programming 
Button switches OFF the Power Saving Mode and the BW-03 operates normally 
again.
Programming
Programming functions are carried out with the help of the Programming / Select 
Button (2, Fig 1A). This button performs the following functions:
1. Changing the displayed voltage.
2. Resetting the alarms.
3. Discontinuing Power Saving Mode.
4. Configuring alarm values (see Table 1).
The first three functions have been covered earlier in this manual so that only the 
programming of the software still remains.
As soon as the Programming Button is pressed for four seconds, the display will 
turn OFF for a moment to indicate that the Programming Menu has been activated. 
Next, “lo” appears in the display, followed by the value 10.8V (21.6V), the default 
value – see Table 1. This means that the undervoltage alarm can be adjusted and 
that it is currently set to 10.8V (21.6V). This value can be changed by pressing the 
Programming Button. If this is done, the value will be increased by 0.1V for each 
press. This continues until the value of 12V is reached. If the button is pressed again, 
the lowest value in the table – 10.5V – is displayed. As soon as the desired value is 
displayed, there is a 4 second delay until “YES” is displayed. This indicates that the 
value chosen has been accepted.
Next, the display remains blank for a moment once again followed by the text "hi". 
Immediately after this, a voltage value (default value of 14.8V (29.6V) - Table 1) is 
displayed once again. This is the overvoltage setting alarm value. This can also be 
adjusted by pressing the Programming Button.
Differential Voltage Alarm
For a 24V system with a centre terminal (see Fig 7), there is also the additional 
option of activating and adjusting a differential voltage alarm. After the overvoltage, 
the display will turn OFF for a moment again followed by the display of “diF”. 
Here again, a voltage value can be selected (default is OFF “---” see Table 1). The 
difference from the previous two values is that now, the value displayed is in millivolts 
and not Volts. Another difference is that here also, the option “---” can be chosen. If 
this is done, the voltage differential alarm is switched OFF.
BATTERY MONITOR BW-03 |
OWNER'S MANuAL
- Auto 12V / 24V detection
- Power Saving Mode 
- Easy to install
- Splash resistant on top