Slow charging help !

[yusuf]

hello friend I have 5.0v and 700ma mobile charger !

and I have 1000mah l-lion battery..

If i use the above mentioned charger then the battery gets full in approx. 1hr 30 minutes..

I am learning slow charging topic..

so if suppose i want to charge this battery in 10hr. then what should I do !

 

[MikeMl]

You have to know something about the chemistry of the battery, and how that particular type of battery shows you that it is charged. It is different for every battery chemistry. Here is some info about LiOn

 

[second286]

To slow the charging time down to 10 hrs, you must decrease the 700 ma output of the charger! Look up the various methods in doing this.

Time to charge = 1000 mah/700ma = 1.43 hr or 1hr and 0.43 hr*60 min/hr = 1hr and 26 min to charge, confirmed by your answer of "approx. 1 hr and 30 minutes..." above.

To charge the battery in 10 hrs, you must decrease the current from 700 ma to;

1000 mah/x = 10 hr

x = 100 ma

This is based on a 5 volt fixed voltage output of your charger, as you indicated in your message.

The charger you are using is the most common charger used in small devices such as cell phones, mp3 players... using a fixed 5 volt source at a specific current level. Most of these small devices are SMART and have built in charging circuits that determine their rate of charge needed from these fixed rate chargers. If not then certain charge parameters may need to be taken into account per battery type. For example in charging lead acid batteries - depending on their state of discharge - will dictate the timing and amount of charge current allowed during the charging cycle.

 

[yusuf]

To slow the charging time down to 10 hrs, you must decrease the 700 ma output of the charger! Look up the various methods in doing this.

Time to charge = 1000 mah/700ma = 1.43 hr or 1hr and 0.43 hr*60 min/hr = 1hr and 26 min to charge, confirmed by your answer of "approx. 1 hr and 30 minutes..." above.

To charge the battery in 10 hrs, you must decrease the current from 700 ma to;

1000 mah/x = 10 hr

x = 100 ma

This is based on a 5 volt fixed voltage output of your charger, as you indicated in your message.

so how should I decrease the output current to 100ma..
can resistor will do the job...

 

[audioguru]

The charger circuit for the Li-ion battery in a cell phone is in the phone. The "charger" is simply a power supply.
Where is your fairly complicated charger circuit?

1) The charger circuit must detect if the battery cell has a voltage lower than about 2.8V then charge at a low current until the voltage rises to about 3.2V.
2) The charger circuit must limit the charging current.
3) The charger circuit must monitor the voltage rising in the battery cell and limit the voltage accurately to 4.20V.
4) The charger circuit must monitor the charging current and shut off when the current drops to about 1/40th of the cell's mAh rating.
5) The charger circuit must monitor the voltage of the discharging battery cell and disconnect it when the voltage drops to about 3.2V.

If you do not follow these rules (use a battery charger IC) then the battery will probably catch on fire. The fire is extremely hot and water makes it burn hotter.