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Charge in the battery after charging for a certain time

  1. Sep 15, 2011 #1
    1. The problem statement, all variables and given/known data

    An ideal 9V battery is connected to a resistive divider consisting of a 330 Ohm and a 600Ohm resistor. A 1.5V rechargeable battery in series with a 1.5k Ohm resistor is connected in parallel with the 330 Ohm resistor. The battery has a capacity of 1200mAh and is half charged. How much charge does it hold after 10 hours?

    [​IMG]

    2. Relevant equations

    V=R*i

    battery charging time = capacity of the battery / charging current power output of the charger:
    hr = mAh / mA

    AAA – AA – C – D sizes rechargeable batteries:
    hours ( charging time ) equals to 12 x Ahr OR 12/100 x mAh ( 12/100 x mAh = hrs )

    Power = V*i

    3. The attempt at a solution

    I tried to find the current going to the 1.5k Ohm dc source. I first combined the R1 and Ri2(internal) as parallel.

    1/Req = 1/330 + 1/1500
    Req= 270.5

    Then I combined R1 to Req since they are in series:

    270.5 + 600 = 870.5 Ohm

    The the total Req is 870.5 Ohm

    Then I tried to find the current passing through the total Req:

    V=Ri
    i=9V/870.5
    i=0.01033

    Then I will use the equation:
    battery charging time = capacity of the battery / charging current power output of the charger:
    = 1200mAH/0.01033
    = 116166 .. wow

    At this point I am totally confused. Since this is such a large number, I feel like I am doing it wrong.

    Any help is appreciated.
     
  2. jcsd
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