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Well this is actually my 3rd version 2nd published one
in a attempt a building a self contained system to get part of my lighting and drip hydroponics system off the grid.

What I have done is to link up a 15w, 1.2 A solar pannel to 2 by 7.2 AH batteries. This I run trough a controller that charges the batteries during the day and then runs the lights at night. During the day I use the system to power my hydroponic motor.



Step 1: Setup Charger

Step one was to set up the panel and the charger unit. I took a PB137 voltage regulator, max 40 volt in @ 1.5A and attached it to a heat sink as my panel will supply up to max of 26v at 1.2A 15w. I think took 3 1N5408 diodes connected in series to the earth pin of the regulator to modify the output to 14.4 to charge my 12v batt

Step 2:

I now take the +/- 14.4v (depending on weather conditions and cloud coverage) and pas sit though the relay up to the to the low battery cut out sensor. this is set to 10v to prevent damage to your batteries from excessive discharge. I need this as I often used to forget to turn off the hydroponic pump.

The batteries are off the pic are 3 x 7.2Ah 12 volt batteries the same used in computer UPS linked in parallel 

Step 3:

Step 3
I set up a day night sensor that I got from a electronics website here this is a 2N3904 NPN Transistor, linked to photo transistor and then using a 100k pot to regulate the sensitivity level. This controls the step 2 relay. At night I am running about 100 ultra bright LED's in and around the house to provide off the grid light and security lights. during the day the relay allows me to run my hydroponic pump

Step 4:

Step 4 
I set purchased a timer relay that they use in electric gates to control the run time of the pump. If  you are anything like me you will forget to switch it off so I had to set up some sort of forget me not system. These units are easy to find and cheap about R100.00 (15usd) this unit has a trigger point and a reset so I inserted to switches on to set it off and then to kill it is I need to. You can set them to run for anything from 30sec to 3 hours. 
I like to give my plants 15min water every 3 hours ... this will be the next step is to build in a 24h timer.

So far day 1 on the system so let us see how she handles the changes and I will get back to you with more info.

Comments and suggestions welcome on how to make the system better and fool (me) proof .....

Step 5:

version 4 
this is the next level .... adding in the controller to protect the bat from over charge and the eventual plan is to add a 12v wind generator and a 24h timer that can be set to water the plants every 3h during the day.

so far i expect the cost to run for the entire set up at less than R200.00 ($25 usd) excluding batt.

To give you all a idea of cost the cheapest controller / charger without low batt, day night, and run timer is R350.00 ZAR ( $40 usd)  the full system would bu\ye pre-built 
Controller R350.00
Day night R125.00
Timer R95.00
Low Bat R45.00
TOTAL R615 ($77.00) .... this is excluding a system to link them together this I have no cost for. 
<p>Can you please elaborate on the different circuits used in this instructable?</p>

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Bio: Crafter, Builder, tinker, potter tailor .... Na just a guy that loves to make things especially if it means making a difference to the world and ... More »
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