Free Charge Controller
From Free Charge Controller
Free Energy. Free Ideas.
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.
Latest Release: v2.00
The Free Charge Controller project has just released its second version! Version 2.00 focuses on implementing a charge controller with MPPT for charging a 12V battery with an 60 Watt solar panel. 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.
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.
The current version of the open source Free Charge Controller is based on the Atmel application note AVR450 which describes how to build a software controlled buck converter for charging batteries. A buck converter steps down voltage from a higher voltage level to a lower 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.
Be sure to check out the podcast interview conducted by Open Source Hardware Junkies. It covers a lot of why this project was created, where it's at, and where it's heading.
The Free Charge Controller is composed of four main hardware blocks:
All schematics and board layouts are designed in Eagle v5.x.
How To Build
The software is under heavy development. We are actively seeking an embedded software expert to oversee the development of firmware
To program the charge controller, you will need an inexpensive AVRISP mkII compatible programmer. Here are a few sources:
- Mengjin Su @ Fun4DIY sells an inexpensive kit. All you need are basic soldering skills. (Currently out of stock)
- USBtinyISP AVR Programming Kit sells for $22 at adafruit industries.
- Search for 'AVRISP' on eBay to find many options.
Follow our guide for setting up the development environment on your computer:
Hardware and Software Downloads
- Version 3.00 Schematic in PDF Format
- Version 3.00 Gerbers + Eagle Schematic and Board files
- Version 3.00 Gerbers confirmed to work with BatchPCB
This is the second, prototype board. The design is being radically changed, but these design files are available for posterity.
- Version 2.00 Schematic & Board Layout in PDF Format
- Version 2.00 BOM with ordering information
- Gerber and Eagle files for creating a V2.00 Board
This is the first, prototype version of the board.