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Solar 3w led fibre optic outside tree decoration Answered

So I have salvaged a solar panel and the battery that it charged from a wireless alarm. The battery is 6v 1.2amps. My plan is to have the panel charge the cell during the day (its Ni-Mh) and using an LDR light a 3w led when its dark. The led will be connected to a number of strands of 1.5mm fibre optic cord, with a number of these attached to a tree to make it look.....nice. I have tested three strands of fibre optic cord with lengths of 2m with a lesser led and all appeared fine.
I have a 3.7v 700ma driver (coming from China) which will drive one 3w led, along with heat sink.
Now is where I am struggling a little, I am not massively experienced in electronics. I think I want a diode attached to the solar panel to avoid battery drain. Then a resistor to reduce my 6v to 3.7-4v and the LDR.
Does this look like it would work in principle? Would the battery run 2 of these drivers/leds or would it discharge too rapidly?
Thanks for any input!

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Josehf Murchison
Josehf Murchison

7 years ago

It is 1 driver and 2 LEDs in series however there is the voltage issue.

So it is driver and LED.

The voltage may not matter since the driver will have a minimum voltage that should be more than 3.7 volts.

The thing that gets me is the battery 1.2 amps or is it 1.2 amp hours because if it is 1.2 amp hours the light will only work for 1 hour at best.

Joe

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earton
earton

Reply 7 years ago

I checked and its 1.2ah also I thought it was ni-mh but its actually lead acid. So if its going to last less than an hour, it may be back to the drawing board! Thanks vey much for taking the time to answer

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Josehf Murchison
Josehf Murchison

Reply 7 years ago

You could try ultra bright LEDs from Radio Shack they run on about 20 ma so it would be a 300 ohm resistor in series with the LED and 6 of them in parallel would run for about ten hours.

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mpilchfamily
mpilchfamily

7 years ago

You need to find a voltage regulator that will take 6v and give you 4V out. An LM317 can be configured to fit the bill here.

No the battery will not run 2 of the drivers. Best case scenario would be wiring 2 of the drivers to the battery in series so the voltage is split. But then the drivers will only get 3V.

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earton
earton

Reply 7 years ago

Thanks, so if I go ahead 1 led it is!