Cell phone battery charge from solar energy

[zedora]

i need help... i want to charge my nokia cell phone battery... i want to charge it by using solar energy...how i will do it by using solar energy? plz help me what i will need to construct solar battery charger...and what will b the circuit?

 

[MikeMl]

Start with a solar panel which delivers an open-circuit voltage about double what is marked on the plug-in charger which came with the phone, i.e. 5V on the charger means get a 10V panel. The panel should be capable of delivering a short-circuit current of at least 100mA in bright sunlight. Use an LM317 as the regulator (**broken link removed**, you will need two capacitors and two resistors). Set the output voltage to match what is printed on the plug-in charger which came with the phone, i.e. 5V. If the plug-in charger is rated at 500mA, a panel rated at only 100mA will take five times longer to charge your phone.

 

[TechnoGilles]

Although in this case, if the panel delivers 100mA at 10V, you should be able to get 200mA at 5V, right ?

 

[MikeMl]

Although in this case, if the panel delivers 100mA at 10V, you should be able to get 200mA at 5V, right ?

MPPT. Requires a sophisticated switcher. My 20Voc, 1Asc panel only puts out ~ 0.7A at 14V, so it is not a straight line...

 

[TechnoGilles]

Gotcha. Thanks !

 

[roltex_rohit123]

find out the voltage of each of the solar cell and its current. you need atleast 350ma at 5.7 volts to use it like a charger. no switcher required. see nokia charger specs. just give the voltage and current and plug it in the charging socket like you plug a charger in it. the pins are readily available. u need satellite grade solar cells those are expensive. put 10 of them in series and see.

 

[SparkMissile]

I doubt you can do it directly if you're going pocket size. You would need some form of a energy storage device to store your energy harvested from the panels such as a li-ion/li-po/nimh battery. I used a MAX1555 from Maxim, set at 100mA using the USB setting and taking input from a 6v 100mA panel. I used a 18650 li-ion battery with a capacity of 2200mAh. From there you can use a variety of step-up regulators to step your battery's output to 5v which most wall warts use. I used a TPS61071 from TI. You need not use another charger ic to charge your phone's battery as the charge ic is embedded in the phone itself.

Solar panel -> Charger -> Battery -> Step-Up Regulator -> Phone

Hope this helps!