How Long Can a 12V Battery Power a 220W Appliance Using a 300W Inverter?

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SUMMARY

The discussion centers on calculating the runtime of a 220W appliance powered by a 12V 100Ah battery through a 300W inverter. Given an inverter efficiency of 70%, the power drawn from the battery is 314W, resulting in a current draw of 26A. Consequently, the estimated runtime before the battery is fully discharged is approximately 3.8 hours, assuming a purely resistive load. The analysis highlights the importance of considering inverter efficiency and load characteristics in such calculations.

PREREQUISITES
  • Understanding of basic electrical concepts, including voltage, current, and power.
  • Familiarity with battery specifications, particularly amp-hours (Ah).
  • Knowledge of inverter efficiency and its impact on power calculations.
  • Ability to perform basic electrical calculations involving Ohm's Law.
NEXT STEPS
  • Research "Inverter efficiency calculations" to understand how efficiency affects power usage.
  • Learn about "Battery discharge rates" and how different loads impact runtime.
  • Explore "Inductive vs. resistive loads" to comprehend their effects on power consumption.
  • Investigate "Power factor" and its relevance in AC circuits for more accurate calculations.
USEFUL FOR

This discussion is beneficial for electrical engineers, DIY enthusiasts, and anyone involved in off-grid power systems or battery management, particularly those looking to optimize the use of batteries with inverters.

Muh1982
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Hello, I have a question, I've googled to find the answer but I didn't find any.

I have 12v 100amp battery, 12v-220v 300watt inverter and 220w 220v appliance.

I want to run the 220w appliance on the 12v battery by using the inverter.

My Question is: How long will it last until the battery is fully discharged?

Please write the equation so it will help me in the future, Thank you.
 
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That would be a 100 amp-hour battery.

It would be useful to know the eficiency of the inverter, but make a guess and call it 70 %

Power into the inverter from the battery = (100 % / 70 %) * 220 watts or 314 watts.

Current into the inverter from the battery = 314 watts / 12 volts = 26 amps.

The battery is 100 amp - hours so the time it would run is 100 amp-hours / 26 amps or 3.8 hours.

However, I have assumed that the load is not inductive or capacitive which could make the result worse.
What are you actually trying to do?
 

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