MCP73831 Li-Ion / Li-Polymer Battery Charger With Charge Complete Status.

Introduction: MCP73831 Li-Ion / Li-Polymer Battery Charger With Charge Complete Status.

Hi and welcome to my 1st instructable.
I have made my own board using Eagle and hade it made by OSH :) It is shared here: Oshpark This instructable will be a little rough around the edges, as it is my 1st one. The project came about since I tried finding something similar, that would show you when the charge is complete and also have the option for "100" mA / "500" mA. The reason was two fold, one, is that smaller batteries can be charged, and the other, that you can still charge using an older style USB 1.1/ 2.0 Hub, that some only provide 100 mA per port.

Step 1: MCP73831 Li-Ion Charger With Both Charging and Charge Complete Led's and 100 / 500 MA Option.

Tools you will need:

  1. Headband Magnifyer highly recommended
  2. Hot air gun/ Hotair rework station or oven
  3. Tweezers
  4. Power adaptor or portable charger
    1. Note: If you are using a smart charger, like the one pictured, do not expect to see the green led, as it will power off due to low current draw!

Steps to assemble:

  1. Solder the switch.
  2. Add the smallest parts to the board and solder them on low fan speed, else they will move away as soon as the solder paste becomes liquid! - Do not put a lot of solder paste, as they will swim!!!
  3. Solder the IC's
  4. Solder the USB
  5. Last, the through hole connector.

Now for those that want to, they can add a standard switch and solder wires to the board. You will need a SPDT switch.

For soldering, I used a hot air gun. you can do the same, or if you have an oven, you can use that.

I have attached the eagle files for those that may want to change around a few things.

In the word document, there are direct links to the products and also for some further reading.

Also, you can watch the video on Youtube, in a slide show version with no audio.

It is located here:

Youtube version

I did take video footage, but it was slightly out of focus, and the sound for the hot air makes it annoying.

Enjoy and happy building.

Total cost: Under $7Aud per board. much more if you do not have the items already.

You are allowed to use the board for personal use. Business/ Professional use not permitted, and also please give due credit if you share this design :)

There is another version with mostly Through hole and of a similar size, of which I will publish over time, and another version is in the works with 10 more LED's and 10 charging levels.

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    6 Discussions


    3 months ago

    How big is this board?


    Reply 3 months ago

    The dimensions are outlined in the first PDF, of which has the following dimensions in mm: 18.72mm = 19mm width by 29.84mm = 30mm height. Converted to cm, including the rounding, that would be 1.9cm or say 2cm x 3cm.
    I hope that helps.
    Also, if you will be using the same switch, please remember to leave a small 5mm (0.5cm) cutout by 1.2mm(0.12cm). Yes, it is a very small switch. Also an opening for the micro-usb and for your charging cables.
    A small clear case is advised for viewing of the led's, else, they can be mounted off-board and attached with fine wires to the case ;-)

    Your options are plenty.

    Wish you all the best with your construction.
    p.s. Click on the image attached to expand it, it is the same as the one from the pdf.

    PCB Dimensions for Charger with inverter V2.JPG

    8 months ago


    i'm really grateful for this info, its going to help me design a similar board, like im wanting the 10-led's for status of charge, havent looked to see if youve already made that version yet, but nevertheless, this is an EPIC-EXPERT-LEVEL piece of awesomeness !!!!

    As i sit here in awe, i sincerely hope you keep up this very inspiring work on open source boards and the use of CadSoft's Eagle for tinkering with, without people like you the world just wouldnt ADVANCE !

    Once again, thanks loads man, totally hats off to ya !


    2 years ago

    In short, with the values of the resistors chosen, you will charge at 80 mA and 465 mA with a charging status, and charge complete status.
    This post is in anticipation of inquiries :)


    2 years ago

    Thanks for sharing :)


    Reply 2 years ago

    Your'e welcome. Thank you for the feedback.