BQ2057WSN Charging issues

[aakash dey]

I have designed a battery charging Module using BQ2057WSN IC to charge a 7.4V,6600mAH Li-ion battery. According to my calculation the charging current is set at 625mA.

The input power source to the Charging module (DC+) is 12VDC, 2A SMPS and the circuit is drawing 625mA from the Power source (SMPS). Now, I have connect a multi meter in series with the battery pack as shown in picture to see how much current the battery is drawing. I have found the multi meter reading as 250mA. The measure battery voltage is 7V, which means the battery is not fully charged.

So, my question is, if the charging circuit is drawing 625mA from the power source, why only 250mA current is drawing by the battery while charging? The battery should also draw the same amount of current (625mA), isn't it?

[jbb]

Thanks for posting schematics.

First thought: is anything getting hot?

Second thought: do you have a second multimeter?  It could be that when you connect the multimeter in series with the battery, the burden voltage (i.e. drop across multimeter innards and test leads) is quite high.  This could make the battery charger reduce the charging current.  Try measuring the voltage across Rsns with a second meter if you can.