when Cell phone battery suppose to b fully charged ???

[drbizzarow]

ASA 2 all
i am working on a cell phone battery charger. usually Lion battery comes 3.6 or 3.7 volt can any body told me at which voltage battery suppose to be fully charged while charging???

Regards

 

[Tahmid]

Hi,
Check for current flow with a shunt resistor. When it comes below 0.05C maybe, charging is complete, at around approximately 3.8V.
Hope this helped.
Tahmid.

 

[drbizzarow]

i have cheked my cel phone battery voltage when its fullly charged, battery voltage was 4.2 volt.

any comments on my observation ?

 

[Tahmid]

Okay, so in your circuit, check for 4.2v or 4.x volt for full charge. Use the ADC of your microcontroller and when the voltage reaches 4.2v, cut off the charging. Which microcontroller are you using? If it is PIC or AVR, I might be able to help with the code and circuit if you need it.
Tahmid.

 

[matbob]

Hi drbizzarow,

Cellphone battery is basically a Lithium-Ion battery and it requires great care for long life. You can't simply charge the battery by providing a constant current or voltage. The charging algorithm used is a constant current charging followed by a constant voltage charging. This would be difficult to implement using discrete components or ADC+ microcontroller. Search for battery management ICs like: BQ2057, ISL6294, etc.

 

[drbizzarow]

yah u r write ... i am using same algo wich followed by simcom. Ie: on deep discharge charge by 5ma constent current at some voltage level with 25ma cc and on third level more then that ....... u can find these values on simcom 300cz
hardwear discription manual.


Regards