Help me in analyzing the circuit diagram of 12v dc UPS!

I've designed a 12v DC UPS.. Anyone good at electronics kindly analyze the circuit i've designed in the image tagged,,, If you feel any problem, kindly help. Also please check for the values of the components used..
Is there any quick transistor switch by which I can replace the BC148B and SL100? as all know the ups need to be very quick... Please help..

If a Lead Acid Battery is in use, you will need some sort of charging regulation to prevent battery damage.

Here is a circuit with description for a sealed lead acid.

http://talkingelectronics.com/projects/BatteryCharger-12vSLA/BatteryCharger-12vSLA.html

As for quick switching, I took an old battery backup apart once,
The battery and rectified DC out where just paralleled with diode isolation. So when the AC dropped the battery just worked, for it was always connected.

It seems T2 base is fixed at the -ve potential so there is no way to switch T2 (and hence T1) on.