How difficult to build a DIY Lithium Ion Battery Charger?

[Galteeth]

Not asking for a schematic, more a notion of roughly how challenging this will be.

 

[0xDEADBEEF]

I read a bit on wikipedia, and it doesn't seem that hard. You charge with a constant current which depends on the battery type until you hit a certain voltage according to the manufacturer's specs around 4.2V per cell, which you hold until there is almost no more current. Does that sound complicated to you? I am sure that there are already ICs available for common Li-battery types.

 

[Bob S]

I read a bit on wikipedia, and it doesn't seem that hard. You charge with a constant current which depends on the battery type until you hit a certain voltage according to the manufacturer's specs around 4.2V per cell, which you hold until there is almost no more current. Does that sound complicated to you? I am sure that there are already ICs available for common Li-battery types.

National has a chip. Look up National Semiconductor’s LM3622 Li-Ion
Battery Charger Controller chip. See also
http://www.national.com/appbriefs/files/AppBrief101.pdf
for a USB-based lithium ion battery charger circuit.
Bob S

 

[Galteeth]

National has a chip. Look up National Semiconductor’s LM3622 Li-Ion
Battery Charger Controller chip. See also
http://www.national.com/appbriefs/files/AppBrief101.pdf
for a USB-based lithium ion battery charger circuit.
Bob S

Interesting thanks. With the chip it seems easy enough.

 

[bjacoby]

National has a chip. Look up National Semiconductor’s LM3622 Li-Ion
Battery Charger Controller chip. See also
http://www.national.com/appbriefs/files/AppBrief101.pdf
for a USB-based lithium ion battery charger circuit.
Bob S

And I would note that you can buy LI Ion batteries on the internet that have a charging/protection circuit built into the end of the battery (I think they are AA cells) which simplifies charging circuits.

 

[YupHio]

BAAADDD IDEA! Charging these beasts is dangerous as it is. I don't mean to be overcautious but I've had one explode in my backyard and it's very dangerous.

 

[YupHio]

Charging these batteries is easier than charging NiMh or NiCad's. I think it would be farly straight farward to detect when charging is completed as there is a very noticable change.