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# Making Solar phone charger what do i need to know? Answered

I just want to know if im missing anything in my solar phone charging design. Heres how it works: i have 9 little solar panals i got out of solar lights that im going to wire in serize. i then hook that up to a car phone charger and presto i have a phone charger. Is there anything im missing or is it realy that simple?

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## Discussions

Current cannot flow backwards in any arrangement of blocked cells.

Take an ohmeter and measure a cell in total dark drawer to measure the resistor it becomes..

Some low power cell panels even with series lo-fw-diode can generate 6+V at full sun on, so a current pull down zener may be needed pic_3..

ok so to fix my aparage problem could i put 6 cells in serize and 3 in parallel and then i would only need 4 diodes right cuz i need one for the the 6 in serize and 3 for the 3 in parallel.

You have to try to sketch it..

6 in series and 3 in parallel with the six needs 4 diodes but

6 in series and the (3 parallel) in series with the six only need 3 diodes..

there are other ways...

ya im confused cuz i tested one of the solar panals with a lode( A SMALL MOTOR) and it said 1.5 volts but whaen i wired 5 up in serize it only read 2 volts. Any idea whats happening

Assuming same sun light, the motor current = load was using more current with the higher voltage then the cells could supply...

You can look at a motor like a resistor and Ohms law I=V/R...

If you raise the voltage the current will increase too...

Solar cells are not perfect power supplies they still have an internal resistance..

Do measure the resistance in the dark, what did you read ?

ok i just want to say thanks alot for the help im sorry i dont know too much. so i dont know how to messure resistance. all i have is a miltimeter and and i dont know how to use that to mesure resistance

well i tryed it and it didnt works o no real use for a sketch now but i dont know what i did wrong

You are missing protection diodes and the fact that these tny cells already struggle to provide 100mA in full sunlight.
Otherwise all fine.

so what do you mean by protection diodes? is it just so that any battery your charging doesnt feed the electrisity back into your solar panals?

If you use multiple solar panels in series or parallel you should have diodes between them to prevent damage when one or more is in the shade while the rest is in the sun.
Bigger panels have them build in but these tiny single panels usually don't have them.
You can try without but I doubt you will get enough power to charge your phone.

so you dont think ill have enought power. humm ive tessed them with a load and they put about 1.5 volts out each and that means i only need about 4 to get the required voltage and i could use the rest to amp up the apmperage (see what i did there ; )