Manual EM-box 3
Hardware 3.1 - REV 3B - JAN 20
Page 19
5.4 Fuse monitoring
SHB bolt fuses are used for the main protection of the consumer connections. The bolt fuses are electronically
monitored by the EM-box at the respective connections. For each connection a red LED indicates the failure of the
corresponding fuse (error message).
If the nut of an unused consumer connection is not tightened or is loosely tightened, this can also lead to an error
message.
5.5 Own consumption EM-box
The EM-box has an own power consumption of < 10 mA in idle mode. This corresponds to a maximum daily
capacity loss of 0.25 Ah/day. Even if the main switch is switched off, this can lead to a complete discharge of the
connected batteries if recharging is not possible.
Therefore, the connection cable from the service battery to the EM-box must be removed if it is not used for a
longer period of time (> 1-2 months, depending on battery capacity) to prevent a deep discharge of the batteries.
Alternatively, a small solar panel (> 20 W) can be used to cover the EM-box's own consumption and to provide an
additional buffer for the batteries.
The EM-box goes into active mode as soon as
a) the discharge current is greater than 1 A or
b) a charging current via the connections 6.7 (combined inverter) is greater than 200mA
c) a charge current across terminals 4 (starter) is greater than 200mA
d) the voltage at terminals 1, 2 (alternator, charger) is greater than 0,5 V of the lowest battery voltage.
e) a voltage is present at the ignition lock signal input on X3
5.6 Overload / Overtemperature / Übervoltage
The EM-box can carry currents up to 250 A (short time). The maximum load capacity also depends on the ambient
temperature. If the currents exceed the maximum load capacity of the EM-box during operation or if the temperatures
measured in the EM-box are too high, the EM-box tries to protect itself. The first step is to display a message on the
PSM monitor indicating that the EM-box is in overload. The second step is to reduce the current. This is only possible
if the EM-box has influence on the charging source. The last step is to interrupt the charge or switch off the main
switch relay to protect the EM-box from destruction.
5.7 Deep discharge disconnect
The EM-box is equipped with a deep discharge protection. This protects the connected batteries from a dangerous
deep discharge. If the battery voltage drops below 9-11 V during discharge, the corresponding main switch is switched
off. A corresponding warning message "Battery X is empty!" appears additionally on the system monitor. If the battery
is to be used in an emergency, a further discharge can be activated by switching on the corresponding main switch
again for 5 minutes. The new disconnection is triggered repeatedly after 5 minutes as long as the (charging) battery
voltage does not exceed 12.0 V for a 12V battery.
