I want to power up my portable DVD player by removing defective li.po 7.4v 1400mah battery and connecting external li.ion 7.2v 3000mah (2X3.6v 3000mah 18650 battery.kindly suggest the charger circuit for the above.
Welcome to ETO!
Google 'Li+ion+charger+2+cells'. That gives you a selection of charge control ICs for 2 cells. It may, however, be cheaper and safer to buy an off-the-shelf dedicated 2 cell Li-ion charger.
I want to power up my portable DVD player by removing defective li.po 7.4v 1400mah battery and connecting external li.ion 7.2v 3000mah (2X3.6v 3000mah 18650 battery.kindly suggest the charger circuit for the above.
Also you can just use the same charger you used for charging your old battery. Both battery types will be 3.6V nominal anyway. And you do not need to worry about the different battery capacities (1400 mA/H and 3000 mA/H) the charger will take care of that. The only difference will be that your portable DVD player will play for at least twice as long with the new batteries.
You can also fit your new batteries in place of the old batteries if they will fit physically that is.