If you use batteries frequently then this project is just for you, ever wondered about how to extend the life of your battery or the amount of charge stored? The first thing is the easiest part first discharge before recharging, but the commercial chargers with this function are quite expensive, the second is more complicated because you must measure the batteries internal resistance.
This project has it all, software controlled charge/discharge rates, monitoring functions, resistance measurement. The interface software has a simple interface with a large plot, which can be exported in .bmp format after each cycle or manually.
What I like mostly about this project is the simple schematic, doesn’t uses micro controller, everything is made trough the parallel port, this way anybody can built it, without the need to dig for programmers, compilers. The necessary ADC and DAC is implemented with discrete components, the ADC used or voltage measurement has 12bit resolution and SAR(sequential approximation register) architecture, the DAC used for current control has only 4 bit resolution. This is a good example to understand these circuits used in many micro controllers internal circuit.
PC controlled battery tester: [link]