Battery powered cell phone charger. Pls help!!!

[holax12]

Hello,

connecting in series 4 x 1.5v @ 1500mA, i got 1500mA @ 6V. This should be sufficient enough to charge an 850mA phone battery. However this set up does not seem to charge the phone yet the phone displayed charging for hours and then finally goes off. What is wrong? Thanks in advance for your response.

 

[blueroomelectronics]

As the external battery voltage drops the phone might switch off the charger mode.

 

[magnatro]

dont use anything other than recommended rating for charging..

 

[holax12]

As the external battery voltage drops the phone might switch off the charger mode.

the external battery voltage is still enough to charge the phone, is it that there is not enough current or what??

 

[ronv]

What is the voltage for the cell phone battery? Does it show more bars after its charge?

 

[4pyros]

connecting in series 4 x 1.5v @ 1500mA, i got 1500mA @ 6V

Probably not. That is max output ratings, you probably are getting much less. Andy

 

[RCinFLA]

It depends on phone but most phones now days have larger batteries, in 1000 mA-Hr or higher.

To charge these batteries the phone relies on the charger to provide a current limit to match the required charge rate for given battery. This relieves phone of having to regulate high currents and increase heat dissipation within phone.

The phones do monitor charge current and battery voltage. They go into linear regulate mode when battery is at 4.2 vdc and the current tapers off.

If you put 4 - AA batteries direct to charger contacts the phone will either detect excessive current and quit charging or perhaps damage the charge regulator in the phone. You need to regulate to 4.5 to 5.0 vdc and current limit to phone battery needs.

If charger input is also USB port then you may also require a 1.5k pull down on D- line for phone to activate its charger circuitry.