From: http://freechargecontroller.com/ Welcome! Welcome to the main website for the open source Free Charge Controller project. The goal of this project is to design a charge controller with maximum power point tracking (MPPT). Maximum power point tracking allows a solar panel, wind turbine, etc to achieve maximum efficiency and deliver maximum power to a load. In this case, a load can be a battery, inverter, or the grid. What Is A Charge Controller? A charge controller is an essential part of any alternative energy system. In its simplest form, a charge controllers job is to make sure the power source (such as a solar panel) 'plays nice' with the load (such as a battery). The simplest implementation of this is a single diode placed in between a solar panel and a battery. This ensures that the battery does not discharge into the solar panel at night. A more sophisticated implementation would be adding the ability for the charge controller to disconnect the solar panel when the batteries are fully charged - in order to prevent over-charging damage to the batteries. An advanced charge controller would implement features such as MPPT. Project Information The Free Charge Controller project has just released its fourth hardware revision! Version 4.04 focuses on implementing a charge controller with MPPT for charging a 12V battery with an 60 Watt (or less) solar panel. The hardware is built on top of an Arduino shield protoboard and is controlled by an Arduino. This is both an open source hardware and an open source software project. All documents, files, and anything you find on this website is free under the terms of the Creative Commons Attribution-Share Alike license. With enough help, it is hoped that future versions will support different battery voltages, off-grid and grid-tied systems, as well as other power sources such as wind turbines, micro-hydro turbines, etc. The Free Charge Controller project is still in its infancy. Version 4.04 represents the first working version. The focal point of effort at this time is encouraging people to build the circuit, use and contributing to the documentation, and assist in the development of a custom PCB Arduino shield. Progress on these fronts, as well as general support, can be viewed on the project mailing list. The current version of the open source Free Charge Controller is based on Tim Nolan's design and article which describes how to build a software controlled buck converter for charging batteries. The hardware (a buck converter) is built on top of an Arduino protoshield and controlled by an Arduino. A buck converter steps down voltage from a higher DC voltage level to a lower DC voltage level. In this case, it would step voltage down from the 18 volts of a solar panel to the 12 volts of a battery. Since the converter is software controlled, it can be programmed to charge any battery chemistry, change its drive frequency to achieve maximum conversion efficiency, as well as implement MPPT to allow a solar panel to deliver maximum power - all without any changes to hardware. We are actively looking for members from the hardware and software communities to help us on our endeavor. Please join us in empowering people to generate their own power. Micropower generation gives people freedom from dependence on foreign oil as well as bills and taxes from the grid. Give people the freedom to use open source hardware and software to enrich their lives. This website is the public face of this project. If you would like to become an active member, you should also join our Yahoo! group where all discussions on future development happen. You can also find out more about the subject of solar and MPPT by exploring some of our Links. Hardware Product Roadmap The Free Charge Controller is composed of four main hardware blocks: Power Supply Buck Converter Voltage and Current Sensing Circuitry SD Card Interface RS232 Interface All schematics and board layouts are designed in Eagle v5.x.