Automatic Voltage Compensation - Victron energy Phoenix 12/30 1+1 Manual De Instrucciones

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4.13. Automatic voltage compensation

The charger compensates for the voltage drop over the DC cables by gradually
increasing the output voltage if the charging current rises.
The fixed voltage offset is 100mV. The voltage offset is scaled with the charge
current and added to the output voltage. The voltage offset is based on 2x 1-
meter cable, contact resistance and fuse resistance.
Example calculation for the 12/50 (1+1):
The cable resistance R can be calculated with the following formula:
�� × ��
�� =
��
Here R is the resistance in ohms (Ω), ρ is the resistivity of copper (1.786x10^-8
Ωm at 25°C), l is the wire length (in m) and A is the surface area of the wire (in
m²).
A widely used distance from charger to battery is 1 metre. In this case the wire
length is 2 metres (plus and minus). When using a 6AWG cable (16mm²) the
wire resistance is:
−8
1,786 × 10 × 2
���������� = = 2.24��Ω
−6
16 × 10
Installing a fuse close to the battery is highly recommended. The resistance of a
standard 80A fuse is:
���������� = 0.720��Ω
The overall resistance of the circuit can then be calculated with the following
formula:
������������ = ���������� + ����������
Therefore:
������������ = 2.24��Ω + 0.720��Ω = 2.96��Ω
The required voltage drop compensation over the cable can be calculated with
the following formula:
�� = �� × ������������
In which U is the voltage drop in volts (V) and I is the current through the wire in
amperes (A).
The voltage drop will then be:
�� = 50 × 2.96��Ω = 148���� for the full 50A charging current.