The originator of this circuit idea is Mr. Uttam Sadhukha, Howrah. He is a circuit designer, and works for helping hobbyists.
This circuit is for 3in1 emergency light. For loadshadings, we need light as well as a fan in summer. Normal emergency lights comes with tube, torch and blinker, as space required for fan is much. But in circuit design it doesn’t matter.
The circuit describes it all. If you need clarification in some areas, please comment below your questions. All parts that are needed is listed in the schematics itself. The charging require 9-0-9 transformer for quicker charging, but keep in mind that it may overcharge the electrolyte so, switch off mains after full charge,
You can easily separate parts of this total circuit to build a 6V charger, or 6V emergency light, or blinker, etc.