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Lithium-Ion Lithium-Polymer Battery Charger Using MCP73831Author
Panagiotis Kalogeris
August 11, 2013

In this page i will present you a miniature Single cell fully intergrated Li-Ion, Li-Po battery charger using microchip's MCP73831. It is a very simple and reliable solution because of the existence of the MCP73831 Ic which does all the "hard" job. This chip provides constant current and constant voltage method which is necessary to be used in order to charge these types of rechargeable batteries.
As you will see only few external components are required (Only 2 resistors, 2 capacitors, and 1 led) which makes it perfect solution for a simple, reliable and cheap Li-Ion, Li-Po battery charger.
Below you will see a small PCB i made (1,6cm x 1,3cm) where Kam developed and soldered it.(Thanks Kam!!!)
The desigh was taken from the MCP73831 datasheet.
Read the worklog and the reference sections for detailed information.


Charger Photos

The Tiny Lithium Charger. Another view of the size. The Pcb in a sided view.

The back side of the Pcb. I will etch the marked area to
use a cable as a vias for better IC cooling.
The charger while charging a Li-Ion battery.

The starting current supplied to the battery. Somewhere in the middle of the charging cycle. That was the last measurement before the chip stopped the charging cycle.

The charging cycle has stopped, and the led switched off. Another type of Li-Ion battery i used. The charger plugged on the battery.

Some measurements i did...

The charging cycle started at 17:42 and ended at 18:38 (56minutes) And the capacity of the battery was 860mAh
The measurements below were made with a Mastech multimeter MY64 (wish to had a Fluke) but someone i know :-)
is going to buy one soon so i will see the reliability according to Fluke's measurements in a while...

0.46A --> 17:42h......(IREG = 1000/2200 =0.454 which makes it correct!!!! Look on the worklog section)
0.41A --> 17:45h
0.43A --> 17:56h
0.37A --> 17:58h
0.32A --> 18:00h
0.29A --> 18:02h
0.22A --> 18:06h
0.19A --> 18:08h
0.15A --> 18:13h
0.10A --> 18:19h
0.07A --> 18:24h
0.06A --> 18:27h
0.05A --> 18:30h
0.04A --> 18:37h
0.00A --> 18:38h

   Continue reading. Click here to view the worklog.



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  • At 1 February 2016, 0:31:26 user mike wrote:   [reply @ mike]
    • I was unable to find suitable polarised connectors so instead I use three pin headers and sockets wired minus/plus/minus so it doesn't matter which way round you plug them in.

  • At 19 January 2016, 10:44:07 user Thien Nguyen wrote:   [reply @ Thien Nguyen]
    • Hello Panagiotis,
      Your circuit is great. So, I really want to see a its schematic. However, I can't open that file. Can you upload it with pdf or send me file pdf?
      Thank you very much!

  • At 10 September 2015, 9:57:19 user Ben wrote:   [reply @ Ben]
    • --Does this charger work for BOTH Li-ion AND Li-polymer cells?

      Yes the MCP73831 works for both battery types.

  • At 7 February 2015, 13:53:59 user Panagiotis Kalogeris wrote:   [reply @ Panagiotis Kalogeris]
    • Hello Declan
      Well I made one more mistake in my last post I wrote (Vcc). I should have written (Vdd) for common anode LEDs and the opposite for common cathode (Vcc). Also the rush schematic I did , it's not very clear (since text editor) if don't understand the way you should connect it I will upload a schematic to the page.
      Regards Panagiotis

  • At 7 February 2015, 8:59:37 user Declan wrote:   [reply @ Declan]
    • Hi Panagiotis,
      Many thanks for your advise.
      I will try both options and let you know how I go.

      ps. have a look at www.ecowatch.co.za

  • At 7 February 2015, 0:30:56 user Panagiotis Kalogeris wrote:   [reply @ Panagiotis Kalogeris]
    • And another way more easiest is to buy a bicolor common anode 3 pin led and connect the common anode to (Vcc) and the other two pins to Stat pin of the Mcp...

      Regards Sorry for the multiple answers...

  • At 7 February 2015, 0:23:11 user Panagiotis Kalogeris wrote:   [reply @ Panagiotis Kalogeris]
    • Forgive me i missed something critical......
      You will also have to connect another one resistor to ground....

      stat pin----------bicolorled----- ----------resistor Vdd
      |----------resostor Vcc

      Hope to understand.


  • At 7 February 2015, 0:10:33 user Panagiotis Kalogeris wrote:   [reply @ Panagiotis Kalogeris]
    • Hello Declan
      You dont need any more schematics to achieve your goal.
      Just buy a bicolor led with 2 pins (not 3) and connect it as the led in the schematic.
      Advise the status output of the mcp where can be found in the worklog tab in order to see how to connect it according the output and your desire.

      ATTENTION>>>> This trick works only with MCP73831 not MCP832

      If you have any more questions feel free to ask again


  • At 4 February 2015, 19:39:00 user Declan wrote:   [reply @ Declan]
    • Great post - I used it and have built a charger that works great.
      How would I connect a bi-color LED?
      Please could you show me a circuit?
      many thanks

  • At 15 September 2014, 10:19:36 user computerman wrote:   [reply @ computerman]
    • Hello Allan,

      I have a question.
      I have 1 cell with this specification 3.7V 2000mAh.
      Did i say it write that i can use a 2K resistor and than the batterij is full in 4 hours.
      Please let me now.
      many thanks.

  • At 15 September 2013, 7:13:26 user Panagiotis Kalogeris wrote:   [reply @ Panagiotis Kalogeris]
    • Hello Allan. The connectors i used are very common in an electronic shop.I found them as "polarized headers" and i think that their designation is due to the fact that you can't place them in an opposite direction.
      Most electronic shops have them in their showcase.
      Now...If you look in the datasheet of the chip says that it can be used for BOTH TYPE batteries. But my friend beware and charge them in a rated current of 1C!!!Look my worklog section for more info.

  • At 5 September 2013, 17:59:56 user Allan wrote:   [reply @ Allan]
    • Thank you, Panagiotis, for taking time to share your work.
      What two-conductor connectors did Panagiotis use to connect/disconnect the cell? Does this charger work for BOTH Li-ion AND Li-polymer cells?

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