Solar Charge Controller (Version 2) for Street Lamp

An improved design of the Charge Controller is made. It consume lower current and uses a 4 stage charging cycle:

1. Bulk Charge,
2. Absorption Charge,
3. Equalization Charge and
4. Float Charge.

This method extends the life of the lead acid battery by desulphating the battery.

The schematic and PCB board is shown below.

When the sun starts charging the battery, the first stage is Bulk charge. It will quickly charge the battery at full current until the battery voltage reaches 14.1V. The next stage, Absorption Charge, where the baterry voltage is maintained at 14.1V for 1.5 times the duration of the Bulk Charge. The charge controller will enters into Pulse Width Moduation (PWM) mode to maintain the battery voltage at 14.1V. After that the PWM will further increase the battery voltage to 14.9V for 0.5 times the duration of the Bulk Charge to desulphate the battery. Finally the battery is considered fully charged and allow to settle down at 13.7V under the control of PWM.

In the laboratory controlled environment, the lead acid battery 12V, 5A-Hr is charge by the solar charge controller using a power supply (simulated solar charging) set at 20Vdc and limited to 1A.

Bulk charging took 3 hours, followed by 4.5 hours under PWM for Absorption Charge and 1.5 hours of Equalization Charge. Finally ends with Float Charge. The battery is fully charge at 100%.

Prototype Solar Street Lamp

A prototype of a street lamp using UPVC pipes is constructed and incorporated with the solar charge controller. Currently it is undergoing field testing to ensure that the charging cycle is behaving according to the 4 stage cycle and the structure design of the street lamp is suitable for outdoor installation.

An aluminum rod of 1.5m is hammered into the ground to provide support of the 1.5 inch UPVC pole structure.

The 1.5 inch UPVC pole is place over the aluminum rod and held secured by bolt and nut.

 

Control Box (Side View)

 

Control Box (Front View)



The control box is held onto the UPVC 1.5 inch pipe using U Bolts.

  

The whole structure of the strret lamp comprising of 5W solar panel, LED lamp and control box (Battery & Charge Controller) is erected. A simple assembly.



 



The LED lights is shown below.



The street lamp in operation at night. The illumination of the LED lights is bright enough for general light of the compund.