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how to cut off supply?

sid2286

Aug 24, 2011
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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
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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Use a proper charger
 

sid2286

Aug 24, 2011
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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!
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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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"
 

sid2286

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

the charger I has got 7.5v 1amp rating on it!
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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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.
 
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sid2286

Aug 24, 2011
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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?
 

CocaCola

Apr 7, 2012
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edit: Here is a fairly simple option.

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
 

BobK

Jan 5, 2010
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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
 
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