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why is one charger quicker than the other?

Discussion in 'Electrical Engineering' started by Anthony Guzzi, May 21, 2011.

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  1. On my phone, the wall charger is twice or 3 times faster than the one in
    my car. Why? (I'm looking for the technical details)


    Thanks
     
  2. Tom Biasi

    Tom Biasi Guest

    "Anthony Guzzi" wrote in message

    On my phone, the wall charger is twice or 3 times faster than the one in
    my car. Why? (I'm looking for the technical details)


    Thanks

    Read the specs on the chargers.
     
  3. Bill

    Bill Guest

    The answer is probably You! That YOU are not willing to pay more than
    a certain amount for a car charger. (When I say you, I mean consumers
    in general).

    Would you pay less than $20 for this... Probably a lot of people
    would.

    Would you pay $80 for this... Probably most people would not.

    Anyway it all has to do with cost/price. Cell phones need a voltage
    other than 12 volts DC car voltage and other than 120 volts AC from a
    house.

    It is inexpensive to convert AC voltage to a different voltage and
    also provide a lot of power.

    But it is quite expensive to convert a DC voltage to another DC
    voltage and also provide a lot of power (amps/watts/charging time). If
    the amps/watts are small, less expensive components can be used. And
    the total price for the product will be less.

    Something similar are car "inverters" which create 120 volts house
    electricity from a car battery. Notice as more amperage/wattage is
    provided by these gizmos, the box gets larger and the price goes up to
    hundreds of dollars.
     
  4. Rich.

    Rich. Guest

    It's all about heat. A straight DC charge, such as from a vehicle, is a
    constant steady flow of current. While on the other hand, the wall charger
    has a ripple to it due to the AC. What happens with the DC is the battery
    become a load, as a load it absorbs power and heats up in the process. Since
    DC is constant, the battery has no cool down cycle. Now with the wall plug,
    the ripple output give you a high and low cycle, or more loosely put, it's
    on-off-on-off-on-off-etc. The off portion of the cycle give the battery a
    cool down period. This cool down period is what's allowing a higher current
    flow into the battery and the subsequent faster charge rate.
     
  5. Don Kelly

    Don Kelly Guest

    "Rich." wrote in message
    It's all about heat. A straight DC charge, such as from a vehicle, is a
    constant steady flow of current. While on the other hand, the wall charger
    has a ripple to it due to the AC. What happens with the DC is the battery
    become a load, as a load it absorbs power and heats up in the process. Since
    DC is constant, the battery has no cool down cycle. Now with the wall plug,
    the ripple output give you a high and low cycle, or more loosely put, it's
    on-off-on-off-on-off-etc. The off portion of the cycle give the battery a
    cool down period. This cool down period is what's allowing a higher current
    flow into the battery and the subsequent faster charge rate.

    A question is "how does the temperature affect the charging rate?" The
    battery resistance is not a major factor involved. So- any information.
    However,whatever the answer is:

    a)While there is a ripple, the battery is still a load with AC.
    b)Sure the load occurs over part of the cycle only but the thermal time
    constants involved are considerably more than a cycle so cooling isn't the
    factor that favours an AC charger.

    Don Kelly
    cross out to reply
     
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