I have a battery powered sensor circuit including a BQ24092. I have used that device to successfully charge a range of Li-Ion 4.2V 10K NTC batteries, with a charge current of about 540mA. Recently, I tried a new battery, one that hasn't been used before, which is a 280mAh 2C 4.2V 10K NTC, the same as the others. However, whilst charging this device I observed 50mA fluctuations the charge current, with a period of about 30ms, most often during the constant voltage phase of the cycle, usually, but not exclusively, as the current drops to about 100mA . In addition, once the termination current is reached, the charger appears to apply about 100mA decreasing back to the termination current over a few seconds, at a rate considerably below the normal top up period. Disconnecting the TS pin completely stops this behaviour.
I was wondering if you had any advice as to how I could go about understanding these observations.
