We are looking for Uninterruptible Power Supply (UPS) 
As all well aware that Pakistan Facing Shortage of power supply 
from its Sources and Power Supply Company imposes 
load shedding ( Power Brake Down ) to all over the Pakistan. 

Every one is not in a capacity to generate Power from Generator, 
So looking for Provide Elec Power supply at low cost. Like UPS

In Pakistan we normally use UPS with External Battery 
UPS charged the 12 or 24 Volts Battery when Power on and 
While power cut off Convert this 12 or 24 VDC to 220 VAC. 
Regarding Backup of this system depend on Battery size which 
may very upon requirements (from 60 AMP to 200 AMP Each,  
one or Two 12VDC ) 

Our Requirements are as follow
When Power ON
Input (for Charging )
180~240 VAC
50/60Hz

Out Put for Charging
18 Volts (for 12 V Battery)
28 Volts (for 24 V Battery)

When Power Off
Input ( for Power Supply)
12 or 24 VDC

Out Put ( for Power Supply)
220VAC + - 2%
50/60 Hz

Working Room Temp
0 ~ 50\'C
Converting time  2~4 MS

As we need long time backup like from 1 hour to 8 hour so 
we need with out batteries.

but if you can provide us Maintenance free battery with Long 
Backup that also ok for us.

Automatic voltage rectify and stable voltage output
Intellectualized CPU control of low battery, recharging, discharging 
protection, and surveillance Indicators by LED for Low Voltage, 
Battery Full, Running on DC or Charging or LCD Screen