The circuit below is a simple Push Pull CD4047 Inverter circuit diagram which uses only few components. It can output 100W to 150W AC power at 10V to 12V battery and centre taped transformer (12V-0V-12V, 5A).
The Integrated Circuit (IC) CD4047 is wired as an astable multivibrator. The two oscillating outputs are out of phase, the 50K variable resistor determine the frequencies of the oscillations. The power MOSFETs (IRF3205) amplifies each half of the alternating voltage produced by the oscillator to the output power transformer which steps up the voltage from 12V DC to 230V AC. However, you can increase the output power to up to 1000W or more by adding more power MOSFETs in parallel, greater power transformer, and larger battery power bank.
Below is the CD4047 Inverter circuit diagram
See also Simple Power Inverter Circuits 100W to 1000W. You may also want to read calculating runtime of power inverter or UPS and battery maintenance tips. Also, you might find Batteries in Series and Parallel Calculations interesting.