Here is a easy way to build your own battery backup to power your computer tv or whatever

Step 1: The Parts

You will need

1 12V car battery or 2 6V car batterys

a car battery charger

a 400 Watt power inverter

some wire

and depending on your battery bolts

Step 2: The Assembley

if your battery has posts replace the bolts with posts

Screw the bolts to the battery and put the battery charger clamps on them

Then wrap the wires from the inverter on the bolts (be sure to check the polarity on all conections before turning anything on) plug the charger in and let it charge the battery

Then when the power goes out plug your stuff into the inverter and you can get several hours of use.