The UPS thread

Post your queries regarding UPSs here...

First mine:-)

Can we make a UPS by combining a modified sine wave inverter and a nice 12 volt charger (say 25 amps) and pairing them with a decent battery?

What will be the approx cost of the 25amp charger and a 1500va inverter be here in pakistan and can you name any outlets in Islamabad/Rawalpindi where they might be available.