Romanized Bangla: Vai 550 ba 555 dc motor diye akta fan baniye dakhan emergency jate kore 3 hours backup pawya jai and sathe kore 3. 7 volt battery diya akta pack banaben jeita diya 3 hours backup pawya jabe ar koto mah per battery koto ah battery hole valo hobe all details bole diben please vai humble request