Solar Battery Charging

Step 3 Main Experiment

Place a full charged 1.2V rechargeable Nimh battery into the battery holder - I assume you know the right way round to insert it. The 1.2V battery on its own will not be enough to light the LED. The 2-3V solar panel will also have a lot of trouble lighting the LED by itself. We can attempt to use the voltage of the battery PLUS the voltage of the solar panel to operate the LED. Below is the solderless version.

Connect the RED POSITIVE terminal of the solar panel to the NEGATIVE leg of the battery holder. Use the extra wire supplied to connect the POSITIVE end of the battery holder to the longer of the two legs of the LED. The longer leg of an LED is always connected to the positive side of the circuit. Then connect the NEGATIVE wire of the solar panel to the other LED leg. If the battery is fully charged and you have a sunny day the LED should light up. You can even power the solar panel from a powerful torch or lamp by shining it onto the panel. Try experimenting by attempting to light the LED with the battery alone, or with the solar panel alone.

Comments

[rhackenb]

I'm a little confused about what end of the solar panel gets connected to the battery holder. In step 3 you say "Connect the RED POSITIVE terminal of the solar panel to the NEGATIVE leg of the battery holder." Yet in the next step you have that wire going into the positive end of the battery holder. I know that step 4 illustrates the use of blocking diode but I think the flow of current is the same. What am I missing? This is a great tutorial and I want to make it work.

[skaar]

the schematic shows serial, the voltages add, so, you can wire it differently, but you get a different effect. parallel for instance, with a bigger panel you'd be able to charge the battery, and run the led, and the battery would run the led at night. in serial, the panel acts as a solar battery. for years i had a hard time figuring out that the hell was going on with the red wires, the plus and minus, but i was reading the web(glory be to the almighty web:P), and found the answer, a supply device, the +(red) is where power comes from, the +(long leg on the diode) on a powered device is where the power goes into. so, with parallel wired devices, the +'s all together, the panel, the battery, the led, all the plusses together.

[siniyaneba]

Hi, so how do i make it parallel? thank you

[skaar]

buh, well, the schematic in the next section shows what you do to charge the battery, you have to reconfigure the wires when you want to switch from charging to running the led... course a dpdt switch could be used to switch the polarity of the panel, then you only have to flip it to change modes. led's are diodes, so, you get one that's rated for the current, you can use the led as the anti-discharge diode.

[DualPhase]

It doesn't really matter where you put the stuff as long as you put it in there the right direction of polarity. meaning possitive and negative are facing the right way. Think of the electricity like a hose. If you kink the hose before the battery or after the battery water (or current) wont flow so it doesnt' matter where you kink it or where you put the led or where you put the diode. It does, however matter if you put possitive "downstream" or "upstream"