Can I build a working model of a solar charging circuit…not optimized…just basically functional…with these elements??
PV Cell - Diode - AAA x 3 battery pack --switch – resistor - LED
I am a teacher and have students working with small solar cells and looking for an interesting circuit that is rooted in clean energy…this seems like a good place to start.
Specifics = 5V 60mA PV cell…so it’s not enough to really charge the battery pack, correct?
The goal is that the battery will power the LED and not get drained by the PV cell…it is not super important that the solar cell actually charges the battery…but that would be great if possible.
What diode would you use? Link?
Hi wesnice.
A Schottky diode would be your best bet for a circuit like this since they have a low voltage drop. We carry a Schottky diode under part number [COM-10926.
Why use a Schottky diode? “Regular” diodes have a voltage forward voltage around 0.6 to 0.7 volts and you only have 0.5v of head room between your solar cell and battery voltage. A regular diode will limit the amount of voltage your solar cell applies to your batteries causing a longer time to recharge. Too much voltage drop will cause the batteries to not fully charge or not charge at all.
Your solar cell doesn’t output much current so it would take quite a long time to charge batteries with it. Assuming you’re using NiMH rechargeable AA cells, it would take roughly 50 hours of direct sunlight to recharge them. Also, don’t forget a current limiting resistor on your LED, you don’t want to burn that out! [330 ohm resistor would do.](Resistor 330 Ohm 1/4 Watt PTH - 20 pack (Thick Leads) - PRT-14490 - SparkFun Electronics)](Schottky Diode - COM-10926 - SparkFun Electronics)
Thank you! That helps a whole bunch. I get pretty confused about the exact components to use, so I appreciate the link.