Thursday, October 18, 2012

the solar light problem

From the CAO I brought home a few of the tops (with all the electronics) of the solar lights. The ones I hacked with red LEDs. They've been performing poorly of late. I occasionally recharged the batteries but it didn't seem to help. Tony remarked on them and suggested possible replacement. I wanted to investigate the problem.

There are two styles of tops. Probably a first then second generation. For sake of discussion, I call one the "plastic top;" the other the "glass top." This refers to the covering on the solar panel proper.

We've seen, the plastic top units fogging and pitting.

I took one of these apart today. I was curious to see if the solar panel could be separated or cleaved. That is, could the plastic be removed from the solar panel silicon chip layer proper. This does not appear to be possible. I was hoping I could split them, that the silicon and wiring would still work, and I could put a new top over the silicon. Perhaps glass.

While I was able to remove entire panel from the top, I did not see a way to split it. But, being able to remove the entire panel easily might offer a refurbishment path that's not too expensive. It would be easy to swap a new for an old (if the correct size).

The plastic top solar panel is marked sl54x54-125 on the back. The panel is 54mm square. Once removed, I could see the copper contacts on the back. Out of curiosity, I did some continuity and voltage checks. Under my halogen desk lamp at low power, the panel puts out good volts! I was surprised. With the light close, the panel kicks out more than 2 volts! That's still plenty to charge the AA cell.

The upshot of this brief analyses is that I wonder if we still have a season or two out of these lights...

I started a test charge.

The glass top type I did not open up.

I wonder if I just need to do a thorough clean. Take 'em apart. Remove debris. Clean battery contacts.

Siliconing the seams around the solar panel will be good to do, to reduce water entering the top and getting into the electronics and the battery compartment. I've seen some take a lot of water and the battery terminals rusting.

Over the winter, I'll recondition the Ni-Cd batteries as best as possible. They're probably developing memory effects. Probably some of these batteries are tired.

I never dated the batteries. Never considered that. I'll start doing that now. That will make it easier, in the future, to replace them.

Also, I found more solar light parts in my garage. Happily, some are compatible with the design we have.

The overall design we're using seems to have been discontinued. Can't get these at Canadian Tire anymore. I've looked on eBay. Someone's offering a box o' 10 for $100. Crazy price. I don't know if we might want to pursue, for spare parts. I don't know which generation of top this is.

I'll try, next spring, to look closely at the new models offered, to see if any parts are still the same. While the exteriors may be different, the guts might be the same.

The more immediate problem we have is that the plastic "lens", below the top, is fragile. We've broken and lost many. We only have a few left. While we have many shafts and other bits.

At some point we might have to switch to a different design.

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