What to do with all these discarded solar lights?

Electronics and electrotechnical stuff
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Location: Australia

What to do with all these discarded solar lights?

Post by Downunder35m »

It is xmas time here and for some years now many xmas lights come with a solar panel and hidden batteries.
And like so many things these days they seem to be only good for one session.
Weeks of harsh UV and weather make the isolation hard and britle, when you unpack them the next year the batteries are dead and once replaced half of the lights fail....
Sounds familiar? Maybe for your halloween decorations? ;)

Most of these lights come with reasonably large panels and two crappy 1.2 rechargable batteries.
But the interesting thing I noticed is that those long string lights, curtain lights and literally anything with lots of LED's seems to work on 36 Volts.
10 LED's in series for all lights I could check.
And those lights as a single diode use very little juice, full brightness often at below 15mA.
Next to impossible to salvage them individually though.

Around 36V is also what most of these LED panel lights for home and office use need.
But they also need around 700mA, which is too much for these solar controllers and batteries to handle.
Some people enjoy what we call rural living - away from people and often ending without electricity.
With most of the time having power it makes no sense to have a fully battery shed and solar panels on standby.
And sadly a combination of grid fed system WITH batteries to be kept charged is somehow impossible ....

Long story short, I visited family over xmas and noticed the new place has rather long and rather dark hallways and areas with low light conditions once the sun goes down.
High ceilings make improving a bit difficult as well.
When we started talking about the problem of things like solar shed lights never having long enough wires the problems started.
How do you explain to someone with no clue about electricity that wires can't be god knows how long when it comes to low voltage DC ? :(
Took me a while...
Then I remembered the xmas lights I almost tossed in the bin.....
Already about 5 meters of thin wire on the panel before it reaches the first LED.

I now ordered a bunch of 10mm LED's and will print some mounting boxes for them once they arrive.
Since I get old and lazy I paid a few cents extra per LED to have them pre-wired for 12V, three in series and another three anti-parallel and off you go.
Calculated that those six on the faked AC the controller provides to get all string lights on will consume about a thrid less in current.
With a bit of luck they should last through the night even at winter times - at least if it is not always cloud covered skies...
Good thing those controller remember the last setting, otherwise you end up with a light show instead of a night light.
Exploring the works of the old inventors, mixng them up with a modern touch.
To tinker and create means to be alive.
Bringing the long lost back means history comes alive again.
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