Charging lithium-ion batteries

[AtomSoft]

hey all back to the battery stuff. I have a lithium-ion battery which is 3.7v @ 1000mAh.

Any thoughts on how to charge it? Some links perhaps?

I read some stuff but not sure. What is this stuff about cells?
How do i know how many cells are in the battery if its a square solid? Or is that just 1? lol

I was looking at :
**broken link removed**

would that be good enough?

 

[Leftyretro]

hey all back to the battery stuff. I have a lithium-ion battery which is 3.7v @ 1000mAh.

Any thoughts on how to charge it? Some links perhaps?

I read some stuff but not sure. What is this stuff about cells?
How do i know how many cells are in the battery if its a square solid? Or is that just 1? lol

I was looking at :
**broken link removed**

would that be good enough?

The basic Li-ion battery chemistry has a single cell nominal voltage of 3.7vdc, therefore in your case you have a single cell. Basically they have a charge method of using a constant current (amount depends on cell MA rating) followed by using a constant voltage once it approaches 4.2 volts. It's important not to overcharge as fire is a real possibility. Also a cell can suffer permanent damage if over discharged, so most items using these kinds of batteries have a auto-turn off when cell reaches around 3 volts or so.
Lots of literature out on these cells and their proper use. Many devices designed to utilize these type cells have a special charger chip embedded into the device.

 

[AtomSoft]

I found this nice info:
https://www.electro-tech-online.com/custompdfs/2008/12/AN10338_1.pdf

Im sure i can apply it to a PIC with out to much work

Also:
https://www.electro-tech-online.com/custompdfs/2008/12/51626a.pdf

which uses a MCP73833 = Stand-Alone Linear Li-Ion / Li-Polymer Charge Management Controller

And its $20 for: MCP73833 Li-Ion Battery Charger Evaluation Board (00117)
and $1.21 for the: MCP73833

Just noticed the packages available ... too small for me but the upside is "MCP73861" its a SOIC and does the same job!(from what i can see)

 

[Chippie]

Why not use Scott Henion's charger? Very versatile and has been built and used my many....I even built and modified it to charge SLA batteries....link is here: SHDesigns - Lithium Ion Charger

 

[AtomSoft]

Thanks ill look into it

They look nicely made and seems pretty cheap to create. Thanks ill try it soon!

 

[lazyhut]

**broken link removed**

how to modify to auto cut off when has been fully charged ?

 

[Chippie]

You need a sense circuit to monitor the current flowing into the battery...set the cut off threshold to a value and then arrange some sort of disconnect...could be a relay or you could use a transistor that is placed in the +ve line to the battery which is turned off when the cell is full....

 

[lazyhut]

You need a sense circuit to monitor the current flowing into the battery...set the cut off threshold to a value and then arrange some sort of disconnect...could be a relay or you could use a transistor that is placed in the +ve line to the battery which is turned off when the cell is full....

can u help to sketch out ?

 

[Chippie]

Here's another link:

Mondo Technology - Pic Project

 

[AtomSoft]

cool thanks that looks simple to make