What resistor to simulate a 2CR5 under load (homemade battery tester)?

Discussion in 'Digital Photography' started by Jack Blake, Jan 1, 2005.

  1. Jack Blake

    Jack Blake Guest

    Hello, and Happy New Year to everybody.

    My battery tester uses a (too weak) 10mA load for its 6V test.

    I'm guessing that a 2CR5 Photo Lithium battery should be tested at
    150mA, under load.

    Any electronics geniuses out there? What type/size resistor should I
    connect to the battery, while testing with my battery meter, to
    simulate a Canon SLR's load, and provide me with an estimation of the
    usability of my 2CR5 (and other 6V lithium) batteries?

    I also have a DMM.

    Thanks for all advise and tips.
     
    Jack Blake, Jan 1, 2005
    #1
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  2. 40 Ohms (or about) will work. 2-W is a good power rating.
     
    Charles Schuler, Jan 1, 2005
    #2
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  3. Jack Blake

    kahout Guest

    Assuming:
    1) your camera represents a 1500 mA load
    2) the battery has a 6 volt potential

    Then R = V / I, so that R = 6 /1.5 =4
    Then W = V x A. so W = 6 x 1.5 = 9

    You would need a 4 ohm, 9 watt minimum resister load.

    If the load is a factor of ten lower (150 mA), then the resistance would be
    40 ohms at 1 watt.

    Kevin
     
    kahout, Jan 1, 2005
    #3
  4. Jack Blake

    Bob Williams Guest

    Digicams are really tough on batteries. I would guess that a camera with
    the LCD screen on, would probably draw 1,000mA.
    So, I would connect a 6 Ohm, 5-10 Watt resistor across the battery
    terminals while measuring the voltage. I'd leave the load on for 5-6
    seconds and see how much the voltage drops in that time.
    For a fresh Lithium Battery, I'd expect the voltage drop to be no more
    than about 0.2-0.3V
    Bob Williams
     
    Bob Williams, Jan 2, 2005
    #4
  5. Jack Blake

    Al Dykes Guest

    Google for "2CR5 specifications" and you'll find manufacturer's pages
    that have electrical specs for the battereies that include
    voltage/current/time graphs.
     
    Al Dykes, Jan 2, 2005
    #5
  6. Jack Blake

    wayne Guest

    I find a light bulb works pretty good at the right voltage and wattage as
    you can see the drain. so a 6V 10 watt should work or an equivalent 12V
    should work fine.

    Wayne
     
    wayne, Jan 2, 2005
    #6
  7. Jack Blake

    Guest Guest

    ( R = E/I ) = ( 6V /.150A ) = 40 OHMS

    ( P = I * E ) = ( .150A * 6V ) = .9W


    A 40 ohm, 2 watt resistor will provide the correct load.


    THO,
    It might be better to go to your local RadioShack,
    get a;

    6v, 100ma bulb
    and a
    6v 150 ma bulb

    for your tester.
    That way, you'll have a quick "visual"
    re the state of your battery.

    ( I'm thinking 100ma load should be adequate for tests )




    <rj>
     
    Guest, Jan 2, 2005
    #7
  8. Jack Blake

    secheese Guest

    A light bulb initially provides close to a dead short across your
    battery because the tungsten starts off relatively cold. I wouldn't
    do this to my camera battery. I think using a resistor as others have
    suggested, is the better plan.
     
    secheese, Jan 2, 2005
    #8
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