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Can we charge a battery using a power supply?

Discussion in 'Power Electronics' started by FlorianB, Aug 13, 2015.

  1. FlorianB

    FlorianB

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    Aug 13, 2015
    Hi!

    Is there any difference between the 2 following scenarios:

    A: I charge a battery using a basic electronically controlled charger that will stop when it judges necessary.
    B: I power the battery with a lab power supply to a voltage slightly above the battery voltage, and I stop once the current is getting close to zero.

    And that leads us to a curiosity question: how does an electronically controlled charger work exactly?

    Thank you!
     
  2. martin the warrior

    martin the warrior

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    Aug 10, 2015
    they measure voltage of the battery once it reaches full it stops. it knows its charged because of voltage/amp readings. here is a link i found by google it: http://www.batterychargers.com/faqs/
     
  3. ADRT

    ADRT

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    Nov 25, 2014
    Depends on what kind of battery. You cannot charge an NiMh battery the same way you charge a lead acid battery.
     
    davenn likes this.
  4. davenn

    davenn Moderator

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    Sep 5, 2009
    as ARDT said, batteries are different and as such all have different charging methods

    so, with that in mind, did you have a particular type of battery in mind ?

    Dave
     
  5. FlorianB

    FlorianB

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    Aug 13, 2015
    Thanks for your replies.
    Yes, Acid battery (12V 7Ah).
    What I'm wondering then is how do they measure the voltage... that means they have to stop charging for a while I guess?
     
  6. ADRT

    ADRT

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    32
    Nov 25, 2014
    Not sure how they do it, but I have done it with an Arduino. Using a voltage divider circuit to cut the voltage down to a safe voltage range for an analog input on the arduino and then calibrating with a bench top PSU to stop charging at about 14.8 vdc. Use a relay to open the circuit to the battery. Automotive relay works great for this. I can give more details if interested.
     
  7. Alec_t

    Alec_t

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    Jul 7, 2015
    Gryd3 likes this.
  8. AnalogKid

    AnalogKid

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    Jun 10, 2015
    Nope. You can measure the battery terminal voltage while it is being charged by connecting the battery terminals to a voltage monitor circuit. Also, if you put a small resistor in series with the battery, you can measure the voltage across the resistor and determine the charge current. Generally speaking, a battery charge circuit does not know what it is attached to. You program it, either digitally for some controllers or with resistors for analog controllers, to tell it at what voltage to shift from full power charging to float, and at what currents to hold at for charging or decrease to for float, or signal an alarm for a damaged cell.

    Linear Technology, maxim, and Unitrode (now TI) make battery charger controllers. Their datasheets and app notes are full of information.

    ak
     
  9. BGB

    BGB

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    Nov 30, 2014
    as others have noted: no.

    rather, you limit charging current to a certain amount (say, 1A). if the battery wants more than this, then the voltage to the battery drops. when the battery nears being fully charged, then the voltage rises to match the charger voltage, and current drops off. depending on the specific charger, it will then switch to a mode where it supplies a fixed voltage (say, 13.6 or 14v), and just sits there (the remainder of the charging happens gradually, with the current dropping to "pretty much nothing" when the battery is done charging).

    the ideal charge current limit depends some on battery capacity and other things. it is typically around 0.3C (say, 2.1A for a 7Ah battery), and is sometimes stated on the battery.
     
  10. Colin Mitchell

    Colin Mitchell

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    Aug 31, 2014
    There are 3 completely different types of Lead Acid Batteries. Which one do you have?
     
  11. FlorianB

    FlorianB

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    Aug 13, 2015
  12. HellasTechn

    HellasTechn

    1,407
    195
    Apr 14, 2013
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