Sorry for being less specific.

The circuit goes like this.

Control Board -- AT89C52 Based main controller Board
Display Board -- 16-1" LCDs using 7211 Display Driver
Keyboard -- 16Key Keyboard
Keypad Display -- 20 Charactor LCD with Backlight
Optical Pulser -- 3 Optical sensors
Relay Board -- 2 Solenoid relays and 1 main motor relay

Now this is a system used for measuring & controlling liquid flow.

Here I have an SMPS as my main power supply (5V/3A) and I have a 6v/10Ah battery which will support the backup for controller card for keeping the Display board, Keypad & Keypad dispaly active even when the mains power is broken.

Kindly suggest.

Sachin