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BQ51013B: High residue current after fully charging

Part Number: BQ51013B

Hello

I am using BQ51013B and another power management chip (converter 5v to 7.4v and control charging) to charge a 7.4v lithium battery.

The problem is the larger current residue of BQ51013B. Here is the problem. I have a power management chip connected behind the BQ51013B to charge the lithium battery(7.4v). When it is fully charged, the chip BQ51013B still withdraw a large current, range from 100mA up to 400mA. We tested the power management chip by connect a 5V powwe to test. It doesn't consume power when the battery is fully charged, therefore I beleive it is BQ51013B consumes the power. The residue current varies with the coil to the charger(from Anker). If the reception coil is at the center of charger coil, the residue current is smaller. When moves the reception coil slightly far away from the charger, the current increases too. For the circuit, I connect a 20k resistor between the RECT pin to FOD pin. Please give me advice what to do. Thanks

  • Hello

    This is probably a normal condition.

    In a no load condition the RX and TX are still operating.  The RX power consumption will be low but TX will still generate a magnetic field and even in a no load condition this will be high. 

    Moving the RX and TX coil away from each other reduces coupling factor and reduces efficiency, more input power required.

    Also if the RX has metal exposed to the AC field it will increase standby power and heating,