Li ion battery


I want to connect single lithium ION battery to VBATT and charge it through 12V car battery.
Can somone tell What needs to be connected to CHG_IN pin of the module exactly.
Can I control the charge / discharge cycle through OPEN AT.


Hi suvidh,

if you want to charge your battery with a 12V car battery,
you need a 12V to 5,1…5,5V voltage regulator because the CHG_IN pin allows only a maximum voltage of 5,5V.

You can control the charge with the AT+WBCM command.

A helpful document is the product specification for Q2400 series.



Thanks Skos,
That was true. I neede to limit voltage to 5.5 V
Actually it was mentioned constatnt current sourse.
So at last i figured out it to be a constant current source with max limiting voltage to 5.5 V.This worked fine for the battery.


There are some switching regulators for this…LM257x and LM259x are the most devices used today…see in After configuration the basic step down circuit, add one current limiter connected through enable pin of the step down regulator.