LI-ION Battery Charger

[rahulshah]

Presently I am making one robot for which i require 12 v source. I have a 12.6V LI-ION battery pack (contains three 4.2V, 1400mAh cells in series), but the problem is I dont have the charger for it. The charge in the market costs high.
So how can I make a charger for the same which is cost effective as well as which can charge fast???
Can I use simply the voltage regulator 78xx series IC???
And what are the things taken to care while designing a charger???
If anyone has a charger circuit please post that to me on my mail ID.
rahuls_shah7388@yahoo.com

Pls reply fast......Its urgent....
Thanks in advance...

With Regards
Rahul Shah

 

[Hero999]

No one's going to email you, it defeats the purpose of a forum devoted to helping everyone. Posting your email is also a bad idea because it can result in spam.

I am also interested in simple ways to charge Lion batteries and would be pretty annoyed if someone sent you a circuit rather than posting it on the open forum where I can see it.

 

[mvs sarma]

Incidentally, it is not out of place to fear, that the batteries might be working, how long back it was charged etc etc. if Rahul knew the source of these batteries, the same source would also have a charger for the same. Yes, LI-ION cell charger might cost more, as sold as a product. as you rightly said, if a mail could reach him indicating a circuit, there is no certainty of its correctness to the extent of not damaging the batteries, leave alone charging. while schematic on the forum is subject to hell of check and critical study by many experienced persons, thus reduce the chances of damage.

 

[audioguru]

A Lithium battery will catch on fire if it is incorrectly charged or discharged. The fire is extremely hot like magnesium and water makes a lithium fire burn hotter.

Lithium battery cells in series each must be monitored because one cell might reach over-charge when the other cells are still charging.

Use a battery charger IC that is made for a lithium type of battery.

 

[Funny NYPD]

Do a quick internet search, you should be able to find one less than US$12 with good quality and all kinds of protection circuits.

 

[rahulshah]

I did searched the net.....but unfortunately there is no such charger at that low cost....

Anyway thanks for your help guys....

 

[Funny NYPD]

Try **broken link removed**
It seems they carry lot of li-ion battery and recharger, such as:
**broken link removed**
**broken link removed**
Find a suite one, it seems all items are worldwide free shipping at this site.
Best Wish

 

[rahulshah]

Try **broken link removed**
It seems they carry lot of li-ion battery and recharger, such as:
**broken link removed**
**broken link removed**
Find a suite one, it seems all items are worldwide free shipping at this site.
Best Wish

Thanks a lot.

 

[audioguru]

The cheap Chinese charger is 4.2V. It won't charge the 12.6V 3-cells in series battery. It doesn't say if it shuts off when the batteries are fully charged.

 

[Funny NYPD]

There might have many different staff which have protection features, you need dig it out. Have fun.

 

[GonzoEngineer]

Goggle the Linear Technology site and you will find a wealth of applications circuits to build a charger, and a detailed explanation of everything you need to monitor and charge them correctly.

I did this about four years ago, and used a circuit right out of their application notes. It worked fantastic, and has never died!