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Bob's Battery Life Chart: How long does a battery last?
Great idea for a science project!
Introduction:
  1. First, numerous leading Alkaline brands were tested against each other.

  2. Since they were practically identical in discharge rates, one brand was chosen and appropriate 5 watt resistors were connected to the test batteries in their battery holders.  NiMH rechagable batteries of that same brand were also tested. 

  3. Voltage measurements were taken over a period of just over one week and noted how many HOURS it took to get down to those points.

  4. At no time were the load resistors disconnected.  As such, this was a continuous drain test.  The current values on the chart represent the current that was being drawn at the beginning of the test when the battery was at 100% of full voltage.

  5. As can be seen on the chart:  The higher the current draw, the shorter the battery life.  Along those lines……Two cell (3V) flashlights draw 375mA, four cell (6V) lanterns and flashlights draw 420mA.  A (6V) blow up mattress pump draws 4.5 Amps and a (9V) portable radio will draw from 20mA up to 150mA depending on the volume setting.
    Bob's Battery Life Chart: August 2007 --- V1.03
    Note: This chart shows the number of HOURS that it takes for a battery’s voltage to drop to a particular percentage. 

    9Volt Alkaline:    
           @12mA    @25mA     @50mA   @100mA  @200mA  
    80% Volts   
    38 18 7 3 1
    70% Volts          55 24 12 5 2
    60% Volts          64 29 14 7 3

    1.5V Alkaline: D Cell     
    @100mA     @200mA    @400mA   @800mA     @1.6A
    80% Volts    125 24 14 5 1
    70% Volts 173 79 35 17 3
    60% Volts   218 98 44 20 6

    1.5V Alkaline: C Cell
    @100mA  @200mA    @400mA   @800mA  @1.6A
    80% Volts    52 18 5 2 .5
    70% Volts 79 35 12 5 1
    60% Volts  98 40 18 8 2

    1.5V Alkaline: AA Cell
    @100mA  @200mA    @400mA   @800mA  @1.6A
    80% Volts 18 8 2 1 --
    70% Volts 29 12 5 2 --
    60% Volts  35 14 7 3 .5

    1.2V NiMH AA Cell: (2500mAh rechargeable)
    @100mA  @200mA    @400mA   @800mA  @1.6A
    80% Volts 10 7 3 1 .5
    70% Volts 10.5 7.5 3.5 1.5 1
    60% Volts  12 8 4 2 1.5
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