Do I Need a Resistor to Lower Voltage for a Solar Cell Phone Charger?

[osnarf]

I'm planning on making a simple solar powered cell phone charger for a demonstration speech in my gen-ed speech class because it seemed like it would be fun at least. The best solar panel I could find for cheap has an output of 6v and 50 mA. My cell phone charger has an output of 5.0v and 700 mA.

Now my question is do I need to use a resistor to lower the voltage of the solar panel, and if I do I assume the output current will be even lower, and will it even cause the cell phone to say it is charging? I imagine it would take forever but as long as it says its charging that's good enough. I could probably afford another one and hook them up in parallel if you think that would help.

Also, out of curiosity, if you used 4 AA batteries in serial to get 6v, would you need to use a resistor to get it to 5v and, if you did, what would be the output current afterwards?

Thank you for your help!

 

[mgb_phys]

Using a resistor is tricky because it depends on the resistance of the phone charger circuit
You are probably OK feeding it 6V - but a fixed 5v output regualtor is very easy to use.

 

[Blenton]

Im sure you can find a better solar cell in an electronics store with at least 500 mA.

 

[Topher925]

50mA is really low. If you decide to use the one you're already looking at then just put a diode in series with it to drop the voltage down to about 5.6ish volts and it should work fine.

 

[wyko97]

sir can i see your circuit design...so that i have a reference about solar panel design cicuit for my thesis.

 

[Evo]

This is a 2 year old thread.

Here are tons of cheap solar cell phone chargers.

http://www.google.com/search?source...4GGLL_enUS339US339&q=solar+cell+phone+charger