Battery (dis)charger and capacity monitor

Forum 2005-2010 (read only) Hardware Interfacing
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Hi,

For a project I need a lithium-ion battery charge/discharge circuit that is able to monitor the battery capacity. This is done by serial logging a discharge of the battery to a predetermined voltage. Battery capacity is calculated by integrating the current/time-to-discharge graph, more information: http://www.tsp.ece.mcgill.ca/~jthiem/projects.html. After that the battery is charged again (a lot of these cycles will be performed to investigate battery degradation).

This is what I've come up with so far. It is a discharging circuit (USB is the serial connection and arduino power) which should work fine and a charging circuit. My concern is the charge part. It utilizes a MCP73833EV evaluation board kit for charging the battery, up to 1A.

circuit diagram in the following post

I know some electronics, but I do not have a lot of experience. So forgive me if the following questions seem to be trivial:)

  1. Somehow I have to cut the charging circuit when a discharge should be performed. What is the most strategic way to do this? Placing a MOSFET on one of the lines, interfaced with the Arduino?

  2. I would like to monitor the batteries' voltage when charging, is this possible or will the charging circuit damage the analog ports of the Arduino?

Thanks in advance! Any other comments are welcome as well.

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