A simple charger for Lithium-ion (Li-Ion) and lithium polymer (Li-Pol) cells here:
**broken link removed**
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A charger project using the MCP73841 charge management controller chip:
MCP73841Li ion li polymer battery charger electronic project circuit diagram | Electronics Projects Circuits Diagrams and Schematics
The choice of that transistor is not critical at all, almost any small signal NPN transistor will do the trick.
Yes, that's OK.
The circuit is for charging a Lithium battery, not for powering a phone that already has a charging circuit inside.
I was pretty convinced you are trying to charge the LiPol ‘battery’ outside the mobile phone. :-D
Usual phone chargers do not require a very accurate voltage output. A large number of phones accept USB charging mode, and it’s OK to supply let’s say 5V up to 7V to the phone, (maximum 300-400mA load current ), so try using any 5V IC power supply.
I want to design a circuit for a cellphone charger. I have found lots of circuits in the net but I can't find a suitable output enough to charge a 3.7v cell phone battery. I tried using 7805 regulator because it is the closest to 3.7v, how do I make the 5v output lower to 3.7v? By the way the power source is a 12v battery 100A. Thanks
Can you check the mobile charger (the one you plug on the wall mains), there should be a label with the rating of the voltage and current .
If we know the voltage that the mobile expects it would be easier to give you an answer.
You don't need to provide the same current, this is just the max current that the specific charger can provide, the internal circuit will get as much as it needs so you can easily use a 5v 1A
0.07A is very low are you sure it is not 0.7A?
Alex
7805 can provide about 1A assuming that the power source can provide it and that you are not exceeding the consumption limits that can create too much heat which triggers the protection.
The battery charging current does control the duration of the charge but in this case you are not in control of the charge current, this is controlled from the internal phone circuit.
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