Quick Answer
To size an RV inverter, calculate the total wattage of appliances, consider the inverter's efficiency, and account for surge currents to determine the required power rating.
Calculating Total Wattage
To determine the total wattage of appliances in your RV, make a list and calculate the power consumption of each device. For example, a 12V refrigerator might draw 60W, a laptop 60W, and a 12V water pump 200W. Sum these values to get the total wattage used by appliances.
Considering Inverter Efficiency
Most inverters are not 100% efficient, so you need to account for their efficiency when sizing the inverter. For instance, a 2000W inverter with 85% efficiency will only produce 1700W of usable power. Consider the efficiency of your chosen inverter when selecting the size.
Surge Current and Overload Protection
When calculating inverter sizing, it’s also essential to consider the surge current of appliances, which can be several times their continuous power rating. A 200W water pump, for example, may surge to 400W when starting. Ensure your inverter can handle these surges and has adequate overload protection to prevent damage. A general rule of thumb is to size the inverter 25% above the total appliance wattage to account for surges.
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