PIC 16F690 - MCP73811 charger for Li-Po (5 cells)

[thunderer]

Hello,
I designed this LiPo charger with a forum fellow. I did the Mikrobasic programming and debugging, he did the hardware (concept and testing).

The project monitors the 5 LiPo cells charged by MCP73811 and displays the DC voltage for the 5 LiPo cells on a 16x2 LCD. When reached 4.21V per cell, a corresponding output shuts-down the charging circuit (logic state "0" on the output for shut-down) after approximative 5 minutes.

The LCD displays as follows:
             ------------------
            |Cell #1: 4.146V   |
            |ON Status: 12345|
             ------------------
The display is updated every second to show the next cell voltage, and so on... The ON status is displayed as long as the 5 minutes have not passed after reaching the 4.21V (=4.209V in reality). When output is put in "0" the corresponding number dissapeares from the screen (i.e. for output 2 OFF line 2 is ON Status: 1 345). When all cells are charged the messages, as follows, apear:
"Charge completed"
"on all 5 cells"
"Press RESET to"
"restart system"

When Reset button is pressed, the PIC is reset and it restarts the cycle. Obviously, if all (or just one) is already charged (4,21V) it will do what I said above. Remember the cells are managed by MCP73811 which protect the cells.

The download link is below. The documentation does not contain PCB, as you guys can choose your own layout based on the packages you have. Schematic (PDF) and source/HEX is all there so you can customize this project on your taste.

If you feel that any improvement is to be made, I encourage you to share your knowledge.

[Parmin]

Hmm,  MCP73831 would do the battery charging and monitoring with automatic charge termination at pre-selectable voltages.
It would even do auto recharge below a preset voltage.
Ok, not as sexy as yours with LCD status, but much simpler and easier to implement IMHO, LED status.


Good job anyhow, and good share.