Get a UPS of your choice and power, I use Mecury; get a 15v, 5Amps Dc power supply or transformer and convert; then buy a 12v battery of your choice, I use 100Amps deep cycle and connect it to the terminals of the UPS. At full charge 10hours noiseless power supply is guarateed every night or day, sequel to your load. note, you can disable the UPS beep; the 15v transformer is the charger, the UPS can charge the battery but it will take a long time. Disconnect the battery from the UPS when charging the battery and disconnect the charger when the UPS is connected.