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how to cut off supply?

Discussion in 'General Electronics Discussion' started by sid2286, Nov 27, 2012.

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  1. sid2286

    sid2286

    102
    1
    Aug 24, 2011
    I've a battery of 4.8v/350ma and a charger wit 6.8v and 1A
    the problem is once the battery is charged , it heats up the battery and the charger and it heats real bad!
    I want to cut off the battery supply once the battery is charged.

    how should I do it?

    regards,
    Sid
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,497
    2,839
    Jan 21, 2010
    Use a proper charger
     
  3. sid2286

    sid2286

    102
    1
    Aug 24, 2011
    thanks Steve !
    I'm aware of that solution, however I'm not able to find a proper charger! I've these chargers in stock so if I get a cut off circuit I can use them :)

    thanks once again though!
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,497
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    Jan 21, 2010
    OK, but you must tell us what sort of battery it is, what sort of charger you're using, and how you intend to determine that the charge is complete.

    Otherwise all we can do is say things like I did above, or other (even less useful) things like "With a switch"
     
  5. sid2286

    sid2286

    102
    1
    Aug 24, 2011
    the battery is nickelcadmium battery wit voltage 4.8v and 1600maH.

    the charger I has got 7.5v 1amp rating on it!
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,497
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    Jan 21, 2010
    Get a proper charger.

    Alternatively you could turn off the charging when the cells get warm.

    You really want to track the rate of change of temperature, but perhaps you can get away with detecting a temperature some number of degrees higher than ambient.

    edit: Here is a fairly simple option.
     
    Last edited: Nov 27, 2012
  7. sid2286

    sid2286

    102
    1
    Aug 24, 2011
    thanks Steve!

    what I did now is connected a Zener of 4.7v between battery terminals.

    I guess that should work, what is your suggestion?
     
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    It may be better than nothing.

    See here.
     
    Last edited: Nov 27, 2012
  9. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    It's links like that, that remind me that I need to build a new charger for my Paslode impulse nailer, there was always a vacant charger on the jobsite so I never bothered replacing my broken one... But, now when I want to use it around the house for a project I need the charger :p
     
  10. Harald Kapp

    Harald Kapp Moderator Moderator

    11,644
    2,691
    Nov 17, 2011
    Steve, that last link of yours is mean :D
     
  11. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    Yeah the fact that you need to purchase the $25 PIC chip kinda defeats any DIY cost effectiveness...
     
  12. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    That is the very article that got me back into electronics. I had two drill drivers that kept wearing out their batteries with its dumb charger. I didn't want to pay for his PIC though, so I got my own and one plussed his design by using a buck converter controlled by the PIC. This was my first of many PIC projects.

    Bob
     
    Last edited: Nov 27, 2012
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