Manual; Battery Capacity - Victron energy Phoenix 12/300 User Manual

5.

BATTERY CAPACITY

If the power ratings are known of the equipment to be powered by the
Phoenix inverter and the duration that the inverter is expected to power the
equipment for, the minimum battery capacity can be calculated.
Make a list of all equipment to be powered by the Phoenix inverter and
sum up each single power consumption multiplied by the duration of time
in hours, during which power will be consumed (Watt-hours). Add the
internal loss of the Phoenix inverter.
The calculation on the internal loss is a two step process. First we calculate
the loss when the inverter is supplying power to a load. The efficiency of
the inverter in this state is 85%, adding roughly 15% to the power
consumption. When the inverter is not supplying power to a load, power
consumption is approximately 8.5W in 'on' mode or 2.5W in 'economy'
mode.
Determine the number of Ah by dividing the power consumption by the
nominal battery voltage (for example 24 V ). The result is the electrical
DC
consumption in Ah's. The result is the total battery capacity-consumption
in Ah's. Multiply this value with a safety factor of 1,7 and the result is the
recommended minimum battery capacity.

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