Charge Controller

Overview


A charge controller, charge regulator or battery regulator limits the rate at which electric current is added to or drawn from electric batteries. It prevents overcharging and may prevent against overvoltage, which can reduce battery performance or lifespan, and may pose a safety risk. It may also prevent completely draining ("deep discharging") a battery, or perform controlled discharges, depending on the battery technology, to protect battery life. The terms "charge controller" or "charge regulator" may refer to either a stand-alone device, or to control circuitry integrated within a battery pack, battery-powered device, or battery recharger.

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

Details
The Open Source Charge Controller for Open Farm Tech was originally being designed in tandem with the Free Charge Controller project; but as of June 2011, it has branched off and become its own project.

The main goal of the Open Source Charge Controller is to: design and produce a robust and multi-use charge controller for the open-source community. When the Open Source Charge Controller project began, the Free Charge Controller was already on hardware revision three, but was behind on firmware. Collaboration then began between Chris Troutner of the Free Charge Controller Group and AJ Manoulian of the Open Source Charge Controller project.

The Open Source Charge Controller hardware design is now being brought over from EagleCAD to KiCAD. While Eagle does offer a free version of its PCB design suite, it is a limited version. KiCAD is a multi-platform (Windows/Linux/OSX)PCB design suite, and is fully open-source; which helps to maintain the full open-source idea behind the project.

The hardware currently supports the charging of a lead-acid battery by a 60 watt solar panel. The charging algorithm is based on the MPPT or Maximum Power Point Tracking theory.

Currently, the firmware originally written for Free Charge Controller is being brought over to the Arduino platform, since it is using the Atmel ATmega16 AVR Chip, to increase the amount of open-source components of the project.

Research

 * Wikipedia: Charge Controller
 * Wikipedia: Maximum power point tracking


 * Free Charge Controller
 * | Arduino Peak Power Tracker Solar Charger
 * 555 charge controller
 * Arduino PPT Solar Charger