amps question

Discussion in 'General Electronics Chat' started by aac9876, May 22, 2007.

  1. aac9876

    Thread Starter Active Member

    Dec 9, 2006
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    0
    this is similar to previous... if a device has a built in 3.6 rechargable
    battery and it says to not charge it onboard with a power supply that exceeds 200 ma...5v.....I thought that any wart 4.5-6 with at least 200 ma is ok.
    do you think that they were wrong or what??? why would they say that??
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    I would tend to take the manufacturer's word for it. Certainly not to exceed the stated maximum voltage. No wall wart regulates well enough to really trust the label, unless you feel like living dangerously.
     
  3. aac9876

    Thread Starter Active Member

    Dec 9, 2006
    124
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    what I meant is the battery will just take what it needs and no more ,right?
    I thought that was the way it worked....
     
  4. mrmeval

    Distinguished Member

    Jun 30, 2006
    833
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  5. cumesoftware

    Senior Member

    Apr 27, 2007
    1,330
    10
    However, you can make one battery recharger based on an op-amp (as a comparator) to monitor the voltage on the battery terminals. You need a transistor in series with a resistor so you can control the current going to the battery (you must always limit the current).
     
  6. Gadget

    Distinguished Member

    Jan 10, 2006
    613
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    What sort of battery..? 3 x NiMH ?? 3 x NiCd ??? 1 x Lithium Ion.. ????

    Capacity... ???
     
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