The following data wasprovided by Mr. Syed through email:
I saw that people are getting educated by your post. So, i think you should explain people about this schematic.
This circuit has astable mutivibrator based on transistors as you did. The capacitors c1 and c2 are the 0.47 for getting output frequency about 51.xx Hz as i measured but it is not constant in all cases.
The MOSFET has reverse high power diode that is used to charge the battery there is no need to add a special diode to the circuit. I've shown the switching principle with relays in the schematic. RL3 must be used with a cutt off circuit.
This circuit is very simple and i've tested it already. I am going to test another design of mine will share with you as soon as test is done. It controls output voltage and stabilize that using PWM. Also in that design i am using transformer 140v winding for charging and BTA16 for controlling the charging amperes. Lets hope for the Good.
You're doing best. Never Quit, Have a wonderful day.
Syed Asim Ali Xaidi
Sam Technology Professionals
Contact : 0320-4058052