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how to charge a 12V battery?

Discussion in 'Electronic Basics' started by StreetMania, Sep 2, 2006.

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  1. StreetMania

    StreetMania Guest

    Hi All, You can see I am a noob. I would like to know how to charge
    batteries? For example, if I have a 1.5v AA battery, what circuit can I
    use to charge it? Resistors? Caps? what about 12V batt? Thanks, Brian
     
  2. Chris

    Chris Guest

    Hi, Brian. Most AA batteries aren't rechargeable. What kind do you
    have?

    Chris
     
  3. You need a power supply with a slightly higher voltage than the
    battery to b e charged, and something (possibly just a resistor) to
    limit the charging current to an acceptable level.

    For a 12 volt car battery, the charging source should be about 14.4
    volts, reducing to 13.6 as the battery approaches full charge.


    --
    Peter Bennett, VE7CEI
    peterbb4 (at) interchange.ubc.ca
    new newsgroup users info : http://vancouver-webpages.com/nnq
    GPS and NMEA info: http://vancouver-webpages.com/peter
    Vancouver Power Squadron: http://vancouver.powersquadron.ca
     
  4. Puckdropper

    Puckdropper Guest

    *snip*
    That looks like 20% of the battery voltage dropped to 10%. Just out of
    curiousity, are you posting from experience, or according to that ratio?

    Puckdropper
     
  5. Experience, and a knowledge of lead-acid battery characteristics.

    A fully charged "12 volt" lead-acid battery (as used in cars) will be
    about 12.6 volts at rest, some time after the charger is disconnected.

    13.6 volts is the "float voltage", at which the battery may be left on
    the charger indefinitely, and will be maintained at full charge. With
    the engine running, a car's electrical system will be somewhere in the
    13.4 - 13.8 volt range, depending on engine speed.

    Further information is available from the battery manufacturers, and
    from "alternate energy" web sites.


    --
    Peter Bennett, VE7CEI
    peterbb4 (at) interchange.ubc.ca
    new newsgroup users info : http://vancouver-webpages.com/nnq
    GPS and NMEA info: http://vancouver-webpages.com/peter
    Vancouver Power Squadron: http://vancouver.powersquadron.ca
     
  6. Bill Bowden

    Bill Bowden Guest

    How about changes in the weather? Does temperature have any effect on
    the "rest" and "float" voltages for a lead acid battery?

    -Bill
     
  7. Bill Bowden

    Bill Bowden Guest

    How about changes in the weather? Does temperature have any effect on
    the "rest" and "float" voltages for a lead acid battery?

    -Bill
     
  8. Ken

    Ken Guest

    Yes. Temperature Compensation
    http://www.ibt-power.com/Lead_acid_tech/lead_acid_tech.html

    To obtain optimum life from the battery, it is recommended that,
    if the battery is to be operated continuously above or below +20°C,
    the charger should be fitted with temperature compensation to prevent
    over and under charging. With an increase of temperature the charge
    voltage should be reduced and, conversely, with a decrease of
    temperature the charge voltage should be increased.
    The temperature coefficient is:

    (1) For cycle use – 5m V / °C / cell

    (2) For standby use (trickle charge of float charge)
    – 3.3m V / °C / cell

    For short-term temperature changes of between 5°C and 35°C it is not
    essential to apply temperature compensation, although it is recommended.
    For temperature fluctuations below 5°C or above 35°C, temperature
    compensation is necessary. Refer to Figure 5 for further details with
    regard to charge voltage set points in relation to temperature.
    Two curves are shown: one for cyclic applications and the other
    for stand-by use.
     
  9. StreetMania

    StreetMania Guest

    Hi Chris,

    I have the 1.5 AA battery from Duracell, they are rechargable but I
    don't have a charger. I like electronics so I like to build a charger
    to charge my 1.5v AA. It's 2500mAh

    Brian
     
  10. Buy their charger.
     
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