Victron energy BlueSolar MPPT 150/70 Manuel page 9

3.4 Optional connections
3.4.1 Voltage Sense
For compensating possible cable losses during charging, two sense wires can be
connected to measure voltage directly on the battery. Use wire with a cross-section of
0,75mm² and insert a 0,1 Amp fuse close to the battery.
During battery charging, the charger will compensate the voltage drop over the DC
cables up to a maximum of 1 Volt (i.e. 1V over the positive connection and 1V over the
negative connection). If the voltage drop threatens to become larger than 1V, the
charging current is limited in such a way that the voltage drop remains limited to 1V.
The warning triangle on the LCD will blink if the voltage drop reaches 1 Volt
3.4.2 Temperature Sensor (see figure 1)
The temperature sensor supplied with the product may be used for temperature-
compensated charging. The sensor is isolated and must be mounted on the battery
minus pole.
3.4.3 CAN bus interface
The charger is equipped with two CAN bus RJ45 sockets.
The CAN bus on this charger is not galvanically isolated. The CAN bus is
referenced to the minus battery connection.
The CAN bus interface will be referenced to ground if the minus pole of the battery is
grounded.
In case of a positive grounded system, a CAN isolation module will be needed to
reference the CAN bus interface to ground.
To prevent ground-loops, the charge controller has an internal 33 Ohm resistor between
CAN-GND and the battery minus output of the charge controller.
3.4.4 Programmable relay
The charge controller is equipped with a potential-free Single Pole Double Throw relay that
by default is programmed according to option 3 below.
The relay can be programmed to energize on one of the following events:
option 1: when the maximum voltage on the PV input is exceeded
option 2: when the temperature protection becomes active
option 3: when the battery voltage becomes too low (adjustable low voltage limit)
option 4: when the charger is in equalisation mode
option 5: when the charger is in error mode
option 6: when the charger temperature drops below -20° C (-40° F)
option 7: when the battery voltage becomes too high (adjustable high voltage limit)
3.4.5 Parallel charging
Several charge controllers can be connected to the same battery.
The PV inputs should not be connected in parallel. Each charge controller
should be connected to its own PV array.
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