Field of invention

This invention relates to the development of solar charger controller that protects battery from over charging and also cost effective. This charger controller is designed and developed using microcontroller. The purpose of microcontroller is to maintain power as well reduce the cost of the board.

Background of the Invention

The existing microcontroller based charger controllers are costly. Our low cost charger controller provides a constant voltage source to battery

Objective of the Invention

This project involves a real time charger controller that works efficiently and provides a constant power to the battery for charging. The main purpose of this charger controller is to protect the battery from over charging and also cost effective.

Summary of the invention

This invention is highly suited to protect the battery from overcharging. Solar panels generate power and this power is not given directly to batteries to avoid over charging. Thus the life time of battery is increased. To protect the battery our charger controller maintains a constant voltage and constant current. Thus delivers a constant power to battery. The maximum input voltage to the charger controller is about 18V and the maximum input current is about 5.5A. The overall capacity of the charger controller is about 100W. This low cost microcontroller based charger

controller can act as an automatic switch for Street lights and also used to control the load like DC fans, DC LEDs etc.

Detailed Description of the invention

A charge controller is an essential part of nearly all power systems that charge batteries, whether the power source is PV, wind, hydro, fuel, or utility grid. Its purpose is to keep your batteries properly fed and safe for the long term.

The basic functions of a controller are quite simple. Charge controllers block reverse current and prevent battery overcharge. Some controllers also prevent battery over discharge, protect from electrical overload, and/or display battery status and the flow of power. Let's examine each function individually.

Photovoltaic panels work by pumping current through your battery in one direction. At night, the panels may pass a bit of current in the reverse direction, causing a slight discharge from the battery. (Our term "battery" represents either a single battery or bank of batteries.) The potential loss is minor, but it is easy to prevent. Some types of wind and hydro generators also draw reverse current when they stop (most do not except under fault conditions). In most controllers, charge current passes through a semiconductor (a transistor) which acts like a valve to control the current. It is called a "semiconductor" because it passes current only in one direction. It prevents reverse current without any extra effort or cost. In some controllers, an electromagnetic coil opens and closes a mechanical switch. This is called a relay. (You can hear it click on and off.) The relay switches off at night, to block reverse current. If you are using a PV array only to trickle-charge a battery (a very small array relative to the size of the battery), then you may not need a charge controller. This is a rare application. An example is a tiny maintenance module that prevents battery discharge in a parked vehicle but will

not support significant loads. You can install a simple diode in that case, to block reverse current. A diode used for this purpose is called a "blocking diode." When a battery reaches full charge, it can no longer store incoming energy. If energy continues to be applied at the full rate, the battery voltage gets too high. Water separates into hydrogen and oxygen and bubbles out rapidly. (It looks like it's boiling so we sometimes call it that, although it's not actually hot.) There is excessive loss of water, and a chance that the gasses can ignite and cause a small explosion. The battery will also degrade rapidly and may possibly overheat. Excessive voltage can also stress your loads (lights, appliances, etc.) or cause your inverter to shut off.

Preventing overcharge is simply a matter of reducing the flow of energy to the battery when the battery reaches a specific voltage. When the voltage drops due to lower sun intensity or an increase in electrical usage, the controller again allows the maximum possible charge. This is called "voltage regulating." It is the most essential function of all charge controllers. The controller "looks at" the voltage, and regulates the battery charging in response.

The voltages at which the controller changes the charge rate are called set points. When determining the ideal set points, there is some compromise between charging quickly before the sun goes down, and mildly overcharging the battery. The determination of set points depends on the anticipated patterns of usage, the type of battery, and to some extent, the experience and philosophy of the system designer or operator. Some controllers have adjustable set points, while others do not.

Claims

We claim that

1 .This hybrid circuit consists of buck and boost devices.

2.Microcontroller without external crystal oscillator.

3.This charger controller makes higher charging efficiency.

4.Longer battery life.

5.Reduces battery overheating.

6.Minimizes stress on the battery.