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--- projects:blinker:work_logs:8_solar_cells [2022/04/03 06:04] – tjhowse
+++ projects:blinker:work_logs:8_solar_cells [2022/04/17 23:45] (current) – tjhowse
@@ Line 50: / Line 50: @@
 All of this testing was done on a single 125x125 solar cell. I have another nine of them to experiment with. I would like to see how these cells respond to a CO2 laser. I work with people who built solar racing cars, and so have experience with this kind of thing. We also have a water jet cutter at work, which might be worth a try.
+==== Unearned success ====
+I was at Bunnings (a hardware store) for an unrelated reason and I saw some solar-powered garden lights with various configurations of solar cells. They were mostly under AUD$10 so I grabbed an 8-solar-cell LED light on a stake.
+{{:projects:blinker:work_logs:pasted:20220417-233721.png}}
+{{:projects:blinker:work_logs:pasted:20220417-233636.png}}
+{{:projects:blinker:work_logs:pasted:20220417-234440.png}}
+I drilled a small hole in the bezel to make the LED visible from the front.
+I connected the 8 cell panel to a blinker circuit and it generates enough power to overwhelm the voltage limiting zener and the supercap overvolted to 3.1V. I did some experimentation with covering up cells with tape, but quickly realised that dark cells don't pass current.
+{{:projects:blinker:work_logs:pasted:20220417-234033.png}}
+I dug through the polymer coating with a hot air gun and knife to expose a connector and soldered on a wire that bypassed two of the cells. This gave me the following results under direct sun when connected to the blinker:
+{{:projects:blinker:work_logs:pasted:20220417-234304.png}}
+I was pretty happy with that, however it did sneak pretty close to the voltage limit of the supercap. I decided I would go with a 5-cell array for the final version.
+{{ youtube>lZiL-H9wsoI?large }}
 ==== Success again ====
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 Repeatable results.
-I will solder five cells into one panel and use that in my first resin-potted prototype.
+{{:projects:blinker:work_logs:pasted:20220404-002747.png}}
+Soldered up one five-cell array.
+I used some fine copper wire to join the cells. I used leaded solder, a chisel tip, Chipquik SMD291 flux and 270ºC. I dipped the wire in the flux and laid it across the contact on the panel, wet the iron tip with a good amount of solder then swept across the copper while I held it in place. Once I got my technique sorted it was pretty straightforward.
+Holding this cell in diffuse sunlight gave 2.7V open circuit voltage.
 ===== Videos =====
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 Success:
+{{ youtube>lZiL-H9wsoI?large }}
 {{ youtube>E3jePteZ7Yw?large }}