Good afternoon,
I am substitute teaching a class in which a student is building a solar usb charger for a science fair project. The circuit diagram the student is using can be found here
http://www.reuk.co.uk/OtherImages/ipod-battery-charger-circuit.JPG
I helped him build the circuit on a breadboard and it seemed to be in working order. The output voltage was just over 5V but the current was only getting up to around 50mA. He was using two Radioshack 6V 50mA solar modules in parallel.
After realizing this wasn't going to work with just the two modules I dug around in the science closet at the school and found what I believe to be electric fencing solar panels mounted on some foamboard. I tested the panels, which put out about 3.5V and have a much higher current (over 200mA). We have tried various configurations with the additional panel(s) (3.5 V cells only, series/parallel with radioshack cells, and just parallel with radioshack cells) and the output voltage drops to 1.6V in the circuit whenever these other panels are used. My questions are: What could be the reason for this? Do we need 500mA to charge his ipod or will a lower current suffice? Would the best thing to do at this point be to find a couple of higher amperage cells?
Thanks for the help!
-Steve
I am substitute teaching a class in which a student is building a solar usb charger for a science fair project. The circuit diagram the student is using can be found here
http://www.reuk.co.uk/OtherImages/ipod-battery-charger-circuit.JPG
I helped him build the circuit on a breadboard and it seemed to be in working order. The output voltage was just over 5V but the current was only getting up to around 50mA. He was using two Radioshack 6V 50mA solar modules in parallel.
After realizing this wasn't going to work with just the two modules I dug around in the science closet at the school and found what I believe to be electric fencing solar panels mounted on some foamboard. I tested the panels, which put out about 3.5V and have a much higher current (over 200mA). We have tried various configurations with the additional panel(s) (3.5 V cells only, series/parallel with radioshack cells, and just parallel with radioshack cells) and the output voltage drops to 1.6V in the circuit whenever these other panels are used. My questions are: What could be the reason for this? Do we need 500mA to charge his ipod or will a lower current suffice? Would the best thing to do at this point be to find a couple of higher amperage cells?
Thanks for the help!
-Steve