Victron energy BlueSolar MPPT 150/70 Manuel page 5

3. INSTALLATION
This product may only be installed by a qualified electrical
engineer.
Important:
In order to enable automatic system voltage recognition always connect the
batteries before connecting the solar panels.
3.1 Location
The product must be installed in a dry and well-ventilated area, as close as possible to -
but not above - the batteries. There should be a clear space of at least 10 cm around
the product for cooling.
The charge controller is intended for wall mounting.
Mount wall bracket (for top holding), make sure it is level.
Put charger on mounting bracket and secure it with two screws in the mounting holes at
the lower backside of the charger.
3.2 Battery cables and battery fuse
Do not invert the plus and minus battery connection: this will
permanently damage the charger.
In order to utilize the full capacity of the product, battery cables with sufficient cross section
and a fuse of sufficient current rating should be used.
Some basic formulas for copper cable:
Resistance Rc (m @47° C) of a cable with length L (m) and cross section A (mm²):
Or, with Rc in (Ohm):
Power loss Pc (W) in a cable carrying current I (A):
Power loss Pc relative to solar array output Pv in %:
Cable cross section required to limit relative power loss to α (%):
(with total cable length 2L)
Rc = 20*L/A (1)
Rc =0,02*L/A (2)
Pc = I²*Rc = 0,02*l²*L/A (3)
α = (Pc/Pv)*100 (4)
A = 2*2L*I/(α*V) (5)
or:
A = 2*2L*Pv/(α*V²) (6)
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