USB charger for mobile charging circuit problem!

[P_rakhunde]

I want to know is it possible to change mAmps rating of mobile charger for safe charging in car.
I want to have circuit; rating like 5V, 800mAmps for my mobile phone battery(Li-ION) charging.
kindly provide the link to this or new power circuit diagram for such ratios.
One more can we calculate the components rating required for such circuits.

 

[jiripolivka]

Be careful- Li Ion battery needs a special charging regulator which can be bought with the particular cell phone only. If you try to build yours, you can destroy the battery quite fast.
I would best check if your phone DC power supply really is 5.0 V, 0.8 A. It means that it has an internal charging regulator and then you can safely use ANY 5V, 0.8 A DC power supply.

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From 12 V car power you can use a 7805 voltage regulator to get 5.0 V, up to 1.0 A. Include a 1 A fuse in the output.