All year round Solar garden light by Lodestone

Last crawled date: 2 years, 12 months ago

I was motivated to design this solar light because I was fed up with the poor performance from commercial lights.
The solar panel is one watt and the battery storage is a 10Ah rechargeable D cell. I'm using a 100uH inductor which gives 10mA into the LED and 33mA drain from the cell this gives a very adaqate light and the LED is very over rated for the job so long life and low phosphor degradation will hopefully be the outcome.
The chip used is a QX5252F this is commonly available from eBay an this wonderfully pragmatic design which has other uses I'm sure, here is the data sheet which is not comprehensive. http://www.mikrocontroller.net/attachment/158139/QX5252.pdf
The solar cells in the round design are very old monocrystalline cells they are very thick and hard to break and easy to work with I have hundreds of them, I realise this is not fare on you and have produced two alternative panels with modern cells which can be obtained from eBay.
There are two types; 19mm x 52mm cells two series banks of four connected in parallel to give two volts at 500mA. And ; 38mm x 52mm cells connected in series to give two volts at 500mA. I have tried both options some skill is required when soldering these cells as they are VERY easy to break. There are encapsulated cells 53mm x 18mm which I have not tried which in theory would fit but only give half the output.
The Perspex top is 4-5mm thick and is easily bent to shape with a hot air paint stripper the shape does serve some purpose as this diffracts and reflects light around. This would work with a plane square top but not be so effective. The Perspex top is glued with epoxy to the panel and the body is fixed to the panel with acetone for ABS (which I am using) and epoxy for PLA (don't know how long this lasts outside).
I have made channels in all the parts to accommodate the wiring and make it easy to assemble without a PCB which maybe novel I'm not sure and would not want to steel any credit.
The D cell holder has extra pads on the corners to stop it lifting and bridging supports on the socket groove all need removing.
The negative contact on the D cell is just a strip of phosphor bronze .2mm thick. I had some knocking around but I see that Rapid sells it.
The spike is a piece of 8mm stainless steel but a bit of zinc plated studding would do if that's what you have.
The connectors I have used are turned pin header and socket which comes in strips and can be cut to size. The output I have plugged onto the end of the LED wires as a plug seemed an unnecessary luxury.
Ill include lots of pictures which I hope will help with construction but please ask if you would like to make one and you have issues.
PS
The funny L shape on the Large square panel is an insulator as one tabbing strip passes over the other.