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| Solar powered garden lights |
WORKING OF CIRCUIT:
Solar panel forms the backbone of the above circuit. The above circuit can be classified into two sections Charging section (From Panel to battery) and Lighting section (From battery to LED's). The Charging section serves the purpose of charging the battery whereas Lighting section powers up the LED's connected to it.
CHARGING SECTION:
The above circuit uses a solar panel rated 16v/5w to charge the battery during day time. A voltage regulator was used to regulate the voltage flow to the battery to avoid fluctuations in the voltage level from panel to battery. An LED was added to indicate the charging of the battery and Diode D1 to avoid panel damage from reverse flow of current during night time.
LIGHTING SECTION:
The Battery is the first thing to consider in the lighting section. This circuit uses a 12v/1Ah (1 ampere current for 1 hour) rated Lead Acid battery to power the whole lighting section. We should ensure that the load didn't draw more current than the specification since it may make the battery dead by draining the charge completely.. A switch was used here to turn the loads on and off by the user.
White LED's are chosen here to do the lighting job in the above circuit since it possess high luminosity and light efficiency. White LED's drop 3-3.5 v and consumes 30mA for working. The Resistors R3,R4....R7 act as current limiters to prevent the damage of the LED's.Now we know both the specification of the battery and LED's used. So lets do some math to calculate the amount of LED's that battery can lighten for the required time period.
This Lead Acid battery can provide 1 ampere current for one hour period. We are here using 15 LED's of five parallel sets in which they are connected in series. We all knew that current through a series connection will be same so summing up the current consumption for 15 LED's as per the above connection we obtain
30mA x 5 = 150mA
Since battery rated 1Ah it can source power to our lighting section for
Battery Source period = 1000mA / 150mA = 6.6 hours
So the battery can source the above 15 LED's around 6 and half hours when its fully charged. But for efficient and long lasting functioning of a battery you must use only 80% of its charge. Hence in the above circuit battery should be used only 5 continuous hours before recharging it for efficient usage.
NOTE:
- You can use other rechargeable batteries in this purpose after calculating load current and the time period your battery can source the load.
- The count of LED's can also be increased but make sure your battery source is robust enough to source the LED's for required time period.
UPDATE:
The Solar panel used to power the circuit was modified to 16v/5W instead of 12V/5W since the 12V panel cannot source sufficient voltage to charge the battery due to the voltage drops by the diode and 7812 IC. If you are intend to use 12V panel itself then kindly replace the 7812 linear regulator IC with Step up Voltage regulator which is capable of providing 12v as output in spite of voltage drops in input.
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Image may be NSFW.
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Image may be NSFW.Clik here to view.
Image may be NSFW.Clik here to view.
Image may be NSFW.Clik here to view.
Image may be NSFW.Clik here to view.
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