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Tiny Solar Power ???

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kimbear

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I have 2 typical $1.00 stiore Garden Lights, each with a 1.5V AA NiCad battery. I need 3 Volts to power a circuit, How can I connect these 2 together while still having them charge from their solar cell, and circuit??
I can only guess that it will require a few steering diodes. This is not a circuit that requires a high degree of design specs, its a simple little circuit for a very simple job.
Thanks in advance
Kim
 

alec_t

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NiCd cells generate only ~1.2V. Would 2.4V be enough for your circuit?
 

kimbear

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HMMM...forgot about that...I guess I'm going to need 3 altogether...same specs as the original question tho
 

ronsimpson

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If you connect the (-) side of one battery to the (+) side of the other battery, then the two will add up.
Just like when you put two batteries in a flashlight.
 

audioguru

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The solar garden light has a white or colors changing LED that needs 3.2V. So it has a circuit that steps up the voltage to 3.2V or more to light the LED at night from the 1.2V from the Ni-Cad cell. A colors changing LED needs a fairly smooth 3.2VDC so there is a series 1N5817 Schottky diode from the rough high voltage then a 0.1uF capacitor to ground to smooth it. Your circuit might need a 10uF smoothing capacitor. The little battery cell and circuit can produce 3.2V at only about 10mA for a few hours.
 

tomizett

Active Member
If you connect the (-) side of one battery to the (+) side of the other battery, then the two will add up.
As Ron says, you can just put the batteries in series.

I still need to consider the 3 solar cells connected to the 3 charging circuits connected to each cell
Leave the solar cells connected exactly as they where originally. Each solar charger circuit sees only its own battery (1.2v or whatever), and won't care what the others are doing. As long at you don't make any other connections between the charger circuits, this should work fine.
 

audioguru

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Will your 3V circuit work with only 2.4V from two Ni-Cad battery cells in series?
Will your 3V circuit work long enough with ONE solar garden light Ni-Cad cell and its circuit board that produces 3.2V?
 

dr pepper

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Another approach, white led's as used in garden lights run at about 3.6v, theres usually a step up circuit in the unit, if you dont need much more current than that used by a led you could use this.
You'd have to suss out how to get the circuit to charge and supply the load at the same time.
 

audioguru

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The low power from the solar panel of a garden light can ONLY charge the low power battery cell when it is all day in sunlight, or it can power a low power load for a while, not both.
 
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