Make:

Dan has a cool low cost Arduino based galvanostat/potentiostat, he writes -

What?
The Ardustat is my open source successor to Jonny Galvo. It uses a standard USB-Arduino unit with a custom designed daughterboard to provide:

* A galvanostat with a current range from .1 µA to 10 mA
* A potentiostat with a potential range from 0 to 5V with 5 mV resolution.

These features are provided from a single USB port on a testing computer. A java based GUI (again, open sourced, written with Netbeans) allows complete control of the ardustat unit, and a custom scripting language, JonnyScript (based on DUALFOIL convention) allows multiple potentiostat and galvanostat commands to be strung together. This lets the ardustat cycle batteries or capacitors for weeks on end with complex charging/loading parameters.

Each Arduino stat costs ~$60 in parts and involves minimal, simple soldering (no surface mount parts, etc). The software runs on just about any modern platform (tested on Windows XP, 2000, Mac OS X, Ubuntu Linux, Fedora Linux).

As a bonus I've written a small php package that allows Ardustat file management and plotting (via gnuplot) over the web. Currently this has only been tested with Ubuntu Linux. A stand alone gnuplot script will work with most any gnuplot distribution. The following links detail the software, hardware

Why?
Email any major manufacturer of battery testing equipment for a quote, wait three days, and see that a basic galvanostat/potentiostat costs $5,000 a channel, without software. The Ardustat does not replace these units (completely, at least). The Ardustat does enable easy, accurate and cheap long term cycling and pulse testing far more easily than most commercial solutions, and again, at a fraction of the price.