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Mobile phone emergency charger

  1. Mar 31, 2012 #1
    Dear Experts

    I bought a single-AA battery emergency cell phone charger.

    It is rated at :
    output : 5.6 v +/- 5%
    current : 400ma

    I plugged it to my samsung note and the phone detected the current and showed it was charging.

    At that time, the battery was charging from 75% level.
    After 5 minutes , I checked and found the charging was on-going but the battery level has dropped to 72%.

    How could it be so?

    I measured the output of the charger and it showed 5.3v at the time it was charging , connected to the phone.

    But sometimes, it shows it was only 3.6v and the phone is still showing its being charged.

    I was wondering could forum experts give me some clues as to what is happening?

    Thanks for reading.

    Have a nice day.

    Best regards
    Ramone :)
  2. jcsd
  3. Mar 31, 2012 #2
    Well, you should provide further information. If it's really charging at 400mA/5.6V, I would expect your AA battery to be dead in about an hour, excluding any losses.
    What's the current flowing from your charger to your phone?
    About the voltage drop, in spite of your phone saying it's being charged, that's gonna be a very slow recharge. It may have happened due to a drop in your battery voltage.
  4. Mar 31, 2012 #3

    jim hardy

    User Avatar
    Science Advisor
    Gold Member

    repeat your measurements with meter set to measure AC volts.

    My guess is the duty cycle changes as AA cell runs down.

    just a guess, though
  5. Apr 6, 2012 #4
    Hi The General and Jim,

    Thanks for your comments.

    Unfortunately, my amp meter is out of order. I have noted your suggestions. Thanks.

    Best regards
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