Inverters and Batteries

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The total rated wattage of the fans is the minimum rated wattage of the inverter unit that must be selected for the duty. Take the total wattage of the fans and multiply by 0.33 hours (assuming "20mts" means 20 minutes run-time on the battery) to give the electrical energy needed during that time in watt-hours. Divide watt-hours by the voltage of the battery pack supplying the inverter to give a battery capacity in amp-hours. Divide by an efficiency of, oh, say 85% to give a required battery capacity upstream of the inverter. Add batteries of similar voltage wired in parallel until the amp-hour ratings of all the batteries added together exceeds the requirements.

Either that or select DC battery-driven fans instead and do away with the inverter.

all izzz well.....but wat is the need for dividing Ah by efficiency.

Efficiency of the inverter - The ratio between the out put power and the input power fed to the inverter. That is the power lost in the conversion. Say your requirement is 100Watts at 110Volt to get this your inverter requires say 12 volt at 10Amps. Then the efficiency of the inverter is 100 watts / 120 watts that is 83.33%. You have to account for this loss in choosing the AH for the battery.

seetharaman

To determine ur battery capacity, check ur load current and compare it with the Amp Hour capacity rating of the battery. If ur load current is 5 Amps, U will need a 60AH battery for (60/5) 12Hrs approximately. Note some energy is consumed in the transformer area that further limits the battery^,s time (not considerably).

Dickson

switch your fan motor to a dc motor, forget trying to build an inverter.