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BQ24165 battery voltage measure

Jake Jung
Expert 1915 points
Other Parts Discussed in Thread: BQ24165

Hi.

I have a question about bq24165 charger ic.

I want to know battery voltage during charging.

For example, when actual battery voltage is 3.5V, I want to measure this voltage at charging state.

When charging state, BQ24165's BAT pin is actual battery voltage=3.5V or VBAT_REG = 4.2V ????

I think BAT pin measured actual VBAT = 3.5V but 4.2V is measured.

Please let me know.

Thanks

  • 0
    TI__Guru**** 153196 points
    The voltage at BAT pin will eventually rise to VBATREG=4.2V. When battery is connected to BAT pin and charging is enabled, V(BAT) = Vbattery + Icharge *(Rbattery+Rconnector+Rtrace/wires) . If you have highly resistive battery or connection, then the charger will be forced into constant voltage mode (i.e. V(BAT)=4.2V) early. To test, disable charging and measure V(BAT).
  • 0 in reply to Jeff F
    Expert 1915 points
    Thanks. Jeff.

    My question is BAT pin's voltage = actual battery voltage + (Ich * impedance) or VBATREG (4.2V)

    For example)
    Charging Voltage = VBATREG = 4.2V
    Battery Total Impedance = 0.1 Ohm
    Charging Current = 1A
    Actual Battery Voltage = 3.5V

    Question)
    When Charging state
    BQ24165's BAT pin voltage is 3.5V + (1A * 0.1 Ohm) = 3.6V ?
    Can I measure 3.6V on BQ24165's BAT Pin?
  • 0 in reply to Jake Jung
    TI__Guru**** 153196 points
    V(BATpin) = V(BAT) + 0.1ohm*Icharge. BAT pin voltage will only be less than battery voltage during discharge when current is flowing the other direction.
  • 0 in reply to Jeff F
    Expert 1915 points

    Thanks Jeff.